REVIEW ARTICLE published: 23 April 2012 doi: 10.3389/fmicb.2012.00130 Secondary metabolites from plants inhibiting ABC transporters and reversing resistance of cancer cells and microbes to cytotoxic and antimicrobial agents

Michael Wink 1*, Mohamed L. Ashour 2 and Mahmoud Zaki El-Readi 1,3

1 Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Germany 2 Department of Pharmacognosy, Faculty of Pharmacy, Ain Shams University, Cairo, Egypt 3 Department of Biochemistry, Faculty of Pharmacy, Al-Azhar University, Assiut, Egypt

Edited by: Fungal, bacterial, and cancer cells can develop resistance against antifungal, antibacterial, or Bruce C. Campbell, Western Regional anticancer agents. Mechanisms of resistance are complex and often multifactorial. Mech- Research Centre, USA anisms include: (1) Activation of ATP-binding cassette (ABC) transporters, such as P-gp, Reviewed by: Jon Y.Takemoto, Utah State which pump out lipophilic compounds that have entered a cell, (2) Activation of cytochrome University, USA p450 oxidases which can oxidize lipophilic agents to make them more hydrophilic and Dominique Sanglard, University of accessible for conjugation reaction with glucuronic acid, sulfate, or amino acids, and (3) Lausanne and University Hospital Activation of glutathione transferase, which can conjugate xenobiotics.This review summa- Center, Switzerland Slawomir Milewski, Gdansk rizes the evidence that secondary metabolites (SM) of plants, such as alkaloids, phenolics, University of Technology, Poland and terpenoids can interfere with ABC transporters in cancer cells, parasites, bacteria, *Correspondence: and fungi. Among the active natural products several lipophilic terpenoids [monoterpenes, Michael Wink, Institute of Pharmacy diterpenes, triterpenes (including saponins), steroids (including cardiac glycosides), and and Molecular Biotechnology, tetraterpenes] but also some alkaloids (isoquinoline, protoberberine, quinoline, indole, Heidelberg University, INF 263, D-69221 Heidelberg, Germany. monoterpene indole, and steroidal alkaloids) function probably as competitive inhibitors e-mail: [email protected] of P-gp, multiple resistance-associated protein 1, and Breast cancer resistance protein in cancer cells, or efflux pumps in bacteria (NorA) and fungi. More polar phenolics (phe- nolic acids, flavonoids, catechins, chalcones, xanthones, stilbenes, anthocyanins, tannins, anthraquinones, and naphthoquinones) directly inhibit proteins forming several hydrogen and ionic bonds and thus disturbing the 3D structure of the transporters. The natural prod- ucts may be interesting in medicine or agriculture as they can enhance the activity of active chemotherapeutics or pesticides or even reverse multidrug resistance, at least partially, of adapted and resistant cells. If these SM are applied in combination with a cytotoxic or antimicrobial agent, they may reverse resistance in a synergistic fashion.

Keywords: ABC transporter, P-gp, MDR, MRP1, secondary metabolites, review

INTRODUCTION in herbivores and microbes. The main group of targets include EVOLUTIONARY AND ECOLOGICAL BACKGROUND (1) proteins, (2) DNA, RNA, and (3) the biomembrane (Wink, Plants are sessile organisms which cannot run away when attacked 2008a,b; Wink and Schimmer, 2010). Neuronal signal transduc- by an herbivore nor do they have an immune system to combat tion is a central and specific target in animals and many SM, infesting parasites, bacteria, fungi, or viruses. From early days of especially alkaloids and amines are directed toward it (Wink, the evolution of land plants they had to cope with these envi- 1993, 2000). SM which interfere with proteins, such as polyphe- ronmental challenges. Plants developed a number of mechanical nols,biomembranes (saponins and other lipophilic terpenoids),or traits, such as resistant epidermal and bark tissues but also spines DNA (alkylating or intercalating mutagens) affect a wider range and thorns as defense tools. In addition, plants evolved a high of organisms, including animals and microbes. In general, mem- diversity of defense chemicals, the so-called secondary metabo- brane and DNA active SM have cytotoxic properties. Affected cells lites (SM; Table 1). Besides defense, some SM function as signal usually undergo apoptosis (Wink, 2007). Several SM interfere with compounds or protect against oxidative or UV stress (Wink, 1988, the neuronal signal transduction in animals and are thus potent 2003, 2008b, 2010a,b). neurotoxins (Wink, 1993, 2000). The structures of SM have been optimized during evolution A large number of SM have lipophilic properties which enable in such a way that they can interfere with molecular targets them to readily pass biomembranes in target organisms by simple diffusion. These SM are also dangerous for the producing plants. Therefore, they are usually stored in dead tissue away from living Abbreviations: ABC, ATP-binding cassette; BCRP, breast cancer resistance protein; MDR, multidrug resistance; MRP1, multidrug resistance-associate protein; P-gp, cells, such as resin ducts, oil cells, trichomes, or cuticles (Wink, P-glycoprotein. 2010b). The absorption of polar SM is usually slower or does not

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Table 1 | Structural types of secondary metabolites and known about 57 active CYP genes are known (Ingelman-Sundberg and structures. Gomez, 2010). A substantial polymorphism of CYPs exists which enables them to metabolize a wide range of xenobiotics. The regu- Class Number of structures lation of the corresponding genes is only partly known. The genes WITH NITROGEN encoding these enzymes, which occur in intestinal epithelia and Alkaloids 21000 in the liver, are inducible by SM that have entered the body. In Non-protein amino acids (NPAA) 700 phase II, the hydroxylated xenobiotics are conjugated with polar Amines 100 molecules, such as glutathione, sulfate, or glucuronic acid. These Cyanogenic glucosides 60 conjugates are eliminated via the kidneys and urine. That means, Glucosinolates 100 on exposure to lipophilic SM, genes which encode these enzymes Alkamides 150 are often induced and that activation can inactivate the toxins. Lectins, peptides 2000 Several SM carry methylenedioxy groups on their phenolic rings, WITHOUT NITROGEN such as in the isoquinoline alkaloids berberine and hydrastine, Monoterpenes (incl. iridoids) 2500 which are assumed to be inhibitors of CYP (Wink, 2007). Alka- Sesquiterpenes 5000 loids which can inhibit CYP have been summarized by Wink Diterpenes 2500 (2007). Triterpenes, steroids, saponins 5000 Resistance mechanisms in bacterial pathogens are even more Tetraterpenes 500 evident because several pathogens already have evolved resis- Phenylpropanoids, phenolic acids, 2000 tance against medicinally used antibiotics. The main mechanisms coumarins, lignans include: Flavonoids, isoflavonoids, anthocyanins, 10000 • stilbenoids, tannins, xanthones Direct inactivation of the antibiotic, e.g., by cleavage of the Polyacetylenes, fatty acids, waxes 1500 beta-lactam ring of penicillin by beta-lactams or acetylation, Polyketides (quinones, anthraquinones) 750 methylation of other antibiotics • Carbohydrates, organic acids 400 Target site modification: molecular change of the target mole- cule (proteins, rRNA) in such a way that the antibiotic cannot bind any longer take place at all, with the exception of SM that can use transporters • Bypass or alteration of metabolic pathways in cases where an for sugars or amino acids or endocytosis as a kind of “stowaway.” antibiotic blocks a pathway (e.g., as for sulfonamides) Furthermore, SM usually occur in complex mixtures which may • Prevention of drug uptake contain SM (such as saponins) that can facilitate the uptake of • Export out of the cell by ABC transporters so that the intra- polar SM (Hebestreit and Melzig, 2003). cellular concentration of an antibiotic (e.g., tetracycline) are reduced. In Bacteria, this is one of several factors responsible THE RESPONSE OF HERBIVORES AND PATHOGENS AGAINST PLANT for multidrug resistance (MDR). DEFENSE CHEMICALS In the evolutionary arms race herbivores and microbes evolved ABC TRANSPORTER mechanisms to avoid or inactivate the defense chemistry of plants. Resistance against defense chemicals can be obtained through the Mechanisms of resistance in animals and humans are complex and expression of ABC transporters that are present in most cells and often multifactorial. Mechanisms include: (1) Activation of ATP- organisms. They are especially active in epithelia of intestinal, liver, binding cassette (ABC) transporters, such as p-gp, which pump kidney, and endothelia (Twentyman and Bleehen, 1991; Nielsen out lipophilic compounds that have entered a cell, (2) activation and Skovsgaard, 1992; Nooter and Stoter, 1996; Steinbach et al., of cytochrome p450 oxidases (CYP) which can oxidize lipophilic 2002; You and Morris, 2007). agents to make them more hydrophilic and accessible for conju- Three types of ABC transporters have been studied in detail: gation reaction with glucuronic acid, sulfate, or amino acids, and (3) activation of glutathione transferase (GST), which can conju- 1. P-glycoprotein (P-gp; molecular weight 170 kD) or MDR1 pro- gate xenobiotics with glutathione. The reactions of CYP,GST, and tein (multiple drug resistance protein) was the first cloned ABC conjugation are well known in pharmacology and categorized as transporter. It is encoded by the ABCB1 gene. P-gp is composed phase I and phase II reactions. These reactions are important in of two similar moieties and each half contains one transmem- the metabolism of medicinal drugs and toxins. This evolutionary brane and one ATP-binding domain. P-gp is an efflux pump history also applies for humans which enables us to metabolize a directed to the gut lumen. The substrate molecules bind to large number of xenobiotics. transmembrane domains and then are exported to extracellu- In phase I, a lipophilic SM is made more hydrophilic by intro- lar space, driven by the energy of ATP hydrolysis. A wide range ducing hydroxyl groups. This reaction is catalyzed by CYP and of lipophilic chemotherapeutical agents, such as anthracenes, CYP1A1, CYP1A2, CYP3A4, and CYP2D6 are the most important anthracyclines, epipodophyllotoxins, taxanes, and Vinca alka- enzymes. Furthermore,these CYP can cleave N -methyl,O-methyl, loids, which can enter tumor cells by free diffusion, are sub- or methylene groups in order to obtain a more hydrophilic or bet- strates of P-gp and can be extruded by the transporter (Loo ter accessible substrate (Guengerich, 2001). In the human genome, and Clarke, 2005).

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2. Multiple resistance-associated protein 1 (MRP1; 190 kD) is are an old invention of nature, which occur from E. coli to encoded by the ABCC1 gene. MRP1 transports drugs conju- Homo sapiens. gated to glutathione (GSH), and also unmodified therapeutics in the presence of GSH (van der Kolk et al., 1999). MRP1 OVERCOMING RESISTANCE CAUSED BY ABC is structurally similar to P-gp, and can expel anthracene- TRANSPORTERS dione, anthracycline, epipodophyllotoxin, Vinca alkaloids, etc. Multidrug resistance reversal agents are also called chemosen- (Wijnholds et al., 2000). sitizers or modulators. They can inhibit the efflux activity of 3. Breast cancer resistance protein (BCRP; 72 kD) is the prod- transporters and other relevant MDR targets (see above); in conse- uct of the ABCG2 gene. It has one transmembrane domain quence they can potentiate cytotoxicity, and are therefore impor- and one ATP-binding domain and only functions after dimer- tant alternatives to overcome MDR (Watanabe et al., 1995; Dantzig ization. BCRP confers resistance to doxorubicin, camptothecin, et al., 1996; Robert and Jarry, 2003). and mitoxantrone (Ambudkar et al., 1999; Schinkel and Jonker, Multi-resistant tumor cells frequently express different ABC 2003; Mao and Unadkat, 2005; Krishnamurthy and Schuetz, transporters simultaneously, e.g., P-gp, MRP1, BCRP, and others 2006). (Annereau et al., 2004; Gillet et al., 2004). Because the substrate spectra of ABC transporters only partly overlap, co-expression Breast cancer resistance protein and P-gp are highly expressed at of transporters might produce more diverse resistance profiles the apical membrane of blood–brain barrier (BBB), placenta, liver, than those of any one member alone. Thus broad-spectrum rever- intestine, and other organs (Schinkel and Jonker, 2003). These sal agents are needed and some compounds exhibit this prop- ATP-driven transporters can pump lipophilic compounds out of erty (Hyafil et al., 1993; Maliepaard et al., 2001; Brooks et al., the cell, either back to the gut lumen or into the blood system, 2003). thus reducing the intracellular concentration of potentially toxic A number of natural or synthetic compounds have been dis- compounds. covered that can inhibit P-gp and re-sensitize resistant tumor ATP-binding cassette transporters are also important at the cells in vitro (Chauffert et al., 1990; Genne et al., 1992; He and BBB. The BBB only allows the entry of small lipophilic sub- Liu, 2002; Wink, 2007). Although these agents work successfully stances by passive diffusion. However, the uptake of lipophilic in some patients, most results of clinical trials were disappoint- compounds in the brain is relatively low due to the high activ- ing (Solary et al., 2000; Dantzig et al., 2001). Some of these ity of P-gp, MRP, and organic anion transporting polypeptides reversal agents did not work in vivo or some had too severe (OATPs). These transporters catalyze a rapid efflux of lipophilic side effects. Therefore, new and better reversal agents are still xenobiotics from the CNS (Elsinga et al., 2004; Mahringer and needed. Fricker, 2010). Most modulators of ABC transporters act by binding to mem- Multidrug resistance was discovered during chemotherapy of brane transport proteins (especially P-gp, MRP1, and BCRP) as cancer patients who developed resistance against a cytotoxic drug. competitive inhibitors, or by indirect mechanisms related to phos- It transpired that the tumor cells were able to pump out the phorylation of the transport proteins, or the expression of the lipophilic alkaloids (such asVinca alkaloids,taxanes,and anthracy- mdr1 and mrp1 genes. Other inhibitors not only act at the level cline derivatives) at almost the same speed as they were entering the of the transporter gene but influence their expression; for exam- tumor cells. Activated cells became resistant to vincristine but also ple, the alkaloid piperine lowered the expression levels of ABCB1, to several other lipophilic drugs. This means that a cross-resistance ABCC1, and ABCG2 genes which encode P-gp, MRP1, and BCRP or MDR had occurred. As a consequence, a major obstacle to the (Li et al., 2011b). successful chemotherapy of tumors is MDR. Upon exposure to xenobiotics MDR genes can become upregulated. Overexpressed INHIBITORS OF ABC TRANSPORTERS FROM PLANTS ABC transporters (P-gp, MRP1, or BCRP) can mediate resistance For this review we carried out a comprehensive literature research. of tumor cells against a variety of anticancer drugs (Schinkel and Table 2 summarizes the search results for SM from plants, which Jonker, 2003). This phenomenon is called MDR, which is one of can serve as ABC transporter substrates and might be useful the most important reasons of chemotherapy failure (Gottesman, in strategies to reverse drug resistance in cancer cells, fungi, 2002). and parasites. Compounds affecting other resistance mechanisms, Several of human protozoal parasites (Plasmodium, Leishma- which are important and which were discussed above, were not nia, Trypanosoma) can develop resistance against prophylactic considered in this review. and therapeutic agents, such as quinolines, naphthoquinones, Lipophilic SM, such as monoterpenes, diterpenes, triterpenes sesquiterpene lactones, and others. The underlying mechanism (including saponins), steroids (including cardiac glycosides), and includes membrane glycoproteins that are orthologous to human tetraterpenes (carotenoids; Table 2) function as substrates for P-gp P-gp. These ABC transporters can also be induced and activated. in cancer cells. The ABC transporter from fungi, AtrB (Andrade ATP-binding cassette transporters are also present in bacteria et al., 2000), or the NorA efflux pump in Staphylococcus aureus can and fungi in which they confer resistance to antibiotics and fungi- also be affected (Smith et al., 2007). Because of their lipophilicity, cidal compounds (Steffens et al., 1996). A medicinally important these terpenoids most likely are substrates for P-gp and other ABC issue is the increasing resistance of bacteria toward antibiotics, transporter. If administered as a chemosensitizer in combination and ABC transporters can be involved in bacterial MDR (besides with a cytotoxic agent they function as inhibitors competing for other mechanisms discussed above). Apparently,ABC transporters binding to the active side of the transporters.

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Table 2 | Secondary metabolites from plants that can inhibit P-gp, MRP1, BCRP,bacterial, and fungal ABC transporters.

Natural product Occurrence Activities Reference

TERPENOIDS Monoterpenes Citronellal, citronellol Zanthoxylum piperitum 1 Yoshida et al. (2005) (Rutaceae) Diterpenes Andrographolide Andrographis paniculata 2 (biphasic action) Najar et al. (2010) (Acanthaceae) Jatrophane diterpene Euphorbia serrulata, E. esula, E. 3 in mouse lymphoma cells Hohmann et al. (2002) polyesters salicifolia, E. peplus (Euphorbiaceae) Latilagascene A, latilagascene Euphorbia lagascae 4, 5 Duarte et al. (2006) B, latilagascene C (lathyrane (Euphorbiaceae) diterpenes) Totarol Podocarpus totara Inhibits Staphylococcus aureus Smith et al. (2007) (Podocarpaceae) NorA efflux pump Triterpenes Aegicerin Clavija procera Reverses MDR in resistant Rojas et al. (2006) (Theophrastaceae) Mycobacterium tuberculosis strains Betulinic acid, pomolic acid Licania tomentosa, 3 in leukemia cells Fernandes et al. (2003) Chrysobalanus icaco, (Chrysobalanaceae) Limonin, deacetylnomilin Citrus jambhiri, Citrus pyriformis, 6 Min et al. (2007), El-Readi et al. (2010) Phellodendron amurense (Rutaceae) Dyscusin A, cumingianol A–F, Dysoxylum cumingianum 3 in cancer cells; 7 Kurimoto et al. (2011a,b) cumingianoside R (Meliaceae) Euscaphic acid, tormentic Cecropia lyratiloba (Moraceae) 3 in leukemia cell line Rocha Gda et al. (2007) acid, 2 α -acetyl tormentic acid, 3β-acetyl tormentic acid Glycyrrhizin Glycyrrhiza glabra (Fabaceae) 2 (biphasic action) Najar et al. (2010) 21α-Hydroxytaraxasterol and Euphorbia lagascae 6, 7 Duarte et al. (2009) related triterpenes (Euphorbiaceae) Obacunone, Phellodendron amurense 1 in MDR cancer cells Min et al. (2007) 12-alpha-hydroxylimonin (Rutaceae) Phytolacca saponins N-1–N-5 Phytolacca americana 3 in 2780 AD cells Wang et al. (2008) (Phytolaccaceae) Sinocalycanchinensin E Sinocalycanthus chinensis Enhances colchicine-induced Kashiwada et al. (2011) (Calycanthaceae) cytotoxicity in MDR KB cells β-Amyrin, uvaol, oleanolic acid Carpobrotus edulis (Aizoaceae) 3 in mouse lymphoma cell line and Martins et al. (2010), Ordway et al. Gram-positive bacteria (2003) Steroids Cardenolides Nerium oleander (Apocynaceae) 3 ovarian cancer 2780AD cells Zhao et al. (2007) Cycloartanes Euphorbia species 8 Madureira et al. (2004) (9,19-cyclopropyl-triterpenes) (Euphorbiaceae) Digoxin, digitoxin Digitalis spp. (Plantaginaceae) 2 de Lannoy and Silverman (1992), Cavet et al. (1996) Ginsenoside Rc, ginsenosides Panax spp. (Araliaceae) 4 in lymphoma cells Berek et al. (2001) Rd, parishin C Methylprototribestin Tribulus terrestris 4 (doxorubicin) Ivanova et al. (2009) (Zygophyllaceae) Protopanaxatriol (ginsenoside) Panax ginseng (Araliaceae) 2, 4 in AML-2/D100 cells Choi et al. (2003)

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Table 2 | Continued

Natural product Occurrence Activities Reference

Stigmasterol, Citrus jambhiri, Citrus pyriformis 1 in Caco2 and leukemia cells El-Readi et al. (2010) β-sitosterol-O-glucoside (Rutaceae) Withaferin A Withania somnifera (Solanaceae) 4 in K562/Adr cells Suttana et al. (2010) Tetraterpenes Carotenoids (lycopene, Capsicum annuum (Solanaceae); 1, 9 Molnar et al. (2004), Kars et al. (2008), violaxanthin, and related Daucus carota spp. sativus Gyemant et al. (2006) compounds) (Apiaceae) PHENOLICS Phenyl propanoids Chlorogenic acid Coffea arabica (Rubiaceae) and 1 Najar et al. (2010) many plants Curcumin, Curcuma longa (Zingiberaceae) 1, 5 Zhou et al. (2004), Limtrakul et al. tetrahydrocurcumin (2007), Hou et al. (2008), Lu et al. (2012) Flavonoids, catechins, chalcones, xanthones, stilbenes, anthocyanins, and related polyphenols Acacetin Several families 1, 10 in human erythrocytes and Wesolowska et al. (2009) breast cancer cells Afrormosin, robinin, Several Fabaceae 1, 10 Gyemant et al. (2005) amorphigenin Ampelopsin Hovenia dulcis (Rhamnaceae) 1, 5 in K562/ADR cells Ye et al. (2009) Apigenin, Several plants 1, 4, 9, 10 in MES-SA/DX5 cells; Zhang et al. (2004), Leslie et al. (2001), substrate for multidrug transporter Perez-Victoria et al. (1999), Wesolowska in Plasmodium falciparum et al. (2009), Angelini et al. (2010) Baicalein Scutellaria baicalensis Substrate for Yorlp and Pdr5p Kolaczkowski et al. (1998) (Lamiaceae) transporters in yeast Saccharomyces cerevisiae Biochanin A Several families 1, 9 Chung et al. (2005), Zhang et al. (2004) Calodenin B, dihydrocalodenin Ochna macrocalyx (Ochnaceae) Inhibit MDR in Staphylococcus Tang et al. (2003) B, and other dimeric aureus (RN4220, XU212, and proanthocyanidins SA-1199-B) Chrysin Several species 1, 2 (biphasic action), 9 Molnár et al. (2008), Gyemant et al. (2005), Zhou et al. (2004), Zhang et al. (2004), Critchfield et al. (1994), de Wet et al. (2001) Chrysosplenol-D, Artemisia annua L. (Asteraceae) Synergistic inhibition of MDR in Stermitz et al. (2002) chrysoplenetin Staphylococcus aureus Cyanidin, callistephin, Glycine max L. Merr. (Fabaceae), 1 Molnár et al. (2008) pelargonin, ideanin, cyanin, Aronia melanocarpa L. pelargonidin, and related (Rosaceae) anthocyanidins Daidzein Several species of Fabaceae 1, 9, 10 Chung et al. (2005), Zhang et al. (2004), Cooray et al. (2004) 5,7-Dimethoxyflavone, Kaempferia parviflora 9(in vitro and in vivo) An et al. (2011) kaempferide (Zingiberaceae) Diosmin Citrus spp. (Rutaceae) 2 Yoo et al. (2007) Ellagic acid, tannic acid Several species Inhibit an efflux pump in Chusri et al. (2009) Acinetobacter baumannii and enhances antibiotic activity Epicatechin, epicatechin Camellia sinensis (Theaceae); 1 in MCF-7/Adr and mouse Martins et al. (2010), Zhang et al. (2004), gallate, epigallocatechin, Carpobrotus edulis (Aizoaceae) lymphoma cell line; 9, 10; 3 in Zhu et al. (2001), Gyemant et al. (2005), epigallocatechin gallate Gram-positive bacteria Mei et al. (2004), Wei et al. (2003) (EGCG)

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Table 2 | Continued

Natural product Occurrence Activities Reference

Fisetin Several species 2, 9 in breast cancer cells; 4 in Chung et al. (2005), Kolaczkowski MES-SA/DX5 cells; substrate for et al. (1998), Angelini et al. (2010) Yorlp transporters in yeast Saccharomyces cerevisiae Formononetin and other Several species of Fabaceae 1, 2, 10 Molnár et al. (2008), Gyemant et al. isoflavones (2005) Galangin Several plant families 2 (biphasic action); 10 Zhou et al. (2004), Critchfield et al. (1994), de Wet et al. (2001) Genistein and derivatives Several species of Fabaceae 1, 2, 9, 10 Zhang et al. (2004), Taur and Rodriguez-Proteau (2008), Leslie et al. (2001), Versantvoort et al. (1994, 1996) Hesperidin, neohesperidin, Citrus jambhiri, Citrus pyriformis 1, 9 El-Readi et al. (2010), Zhang et al. nobiletin, Tangeretin (Rutaceae) (2004), Ofer et al. (2005) Icariin Epimedium grandiflorum 1, 5 Liu et al. (2009) (Berberidaceae) Isobavachalcone Dorstenia barteri (Moraceae) Inhibits efflux pump in Kuete et al. (2010) Gram-negative bacteria Kaempferol, morin, taxifolin, Several plants 2 (biphasic action); 1 and OCT, 9, 10 Zhou et al. (2004), Zhang et al. spiraeoside, and related (2004), deWet et al. (2001), Gyemant flavonoids et al. (2005) Luteolin and its glycosides Several plants 1, 9, 10 Zhang et al. (2004), Nissler et al. (2004) Mangiferin, norathyriol, and Mangifera indica (Anacardiaceae) Modulate the function of [8, 34, 35] Najar et al. (2010), Chieli other xanthones MDR1/P-glycoprotein (P-gp ABCB1) et al. (2010) multidrug transporter. (biphasic action) Naringin, naringenin, and Euphorbia lagascae, Euphorbia 1, 9, 10; substrate for MDR1 in Chung et al. (2005), Zhang et al. derivatives tuckeyana (Euphorbiaceae); Plasmodium falciparum (2004), Ofer et al. (2006), Leslie Citrus hybrids (Rutaceae) et al. (2001), Perez-Victoria et al. (1999), de Castro et al. (2007, 2008), Wesolowska et al. (2007), Duarte et al. (2010) Pentagalloylglucose Several species 1 in MDR KB-C2 cells Kitagawa et al. (2007) (gallotannin) Phloretin, phloridzin Several species 1, 9 Molnár et al. (2008), Zhang and Mor- ris (2003), Zhang et al. (2004), Gye- mant et al. (2005) Plagiochin E Marchantia polymorpha Reverses the efflux pump in Guo et al. (2008) (Marchantiaceae) Candida albicans Quercetin, Several species 1 and OCT in MDR cancer cells; 9, Scambia et al. (1994), Kolaczkowski 3,4,7-trimethoxyquercetin, 10; substrate for Yorlp in yeast et al. (1998), Shapiro and Ling (1997), quercetagetin, hesperetin, Saccharomyces cerevisiae Conseil et al. (1998), Cooray et al. isoquercitrin, myricetin, and substrate for MDR1 in Plasmodium (2004), Ofer et al. (2005), Ohtani derivatives falciparum. et al. (2007), Leslie et al. (2001), Zhang et al. (2004) Resveratrol Several plants 7, 9 Cooray et al. (2004) Rotenone Derris spp., Tephrosia spp., 1 Molnár et al. (2008), Gyemant et al. Lonchocarpus spp. (Fabaceae) (2005) Rutin Several species 1 and OCT; substrate of MDR in Ofer et al. (2005, 2006), Foster et al. Plasmodium falciparum (2001), Perez-Victoria et al. (1999)

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Table 2 | Continued

Natural product Occurrence Activities Reference

Silymarin (isosilybin, Silybum marianum (Asteraceae) 1, 4, 5, 9 in cancer cells Zhou et al. (2004), Agarwal et al. silychristin, silydianin, silybin) (2006), Zhang and Morris (2003), Zhang et al. (2004), Trompier et al. (2003) Tiliroside Platanus orientalis (Platanaceae), 5; inhibits (NorA) efflux protein in Falcao-Silva et al. (2009) Herissantia tiubae (Malvaceae) Staphylococcus aureus Tricin Sasa borealis (Gramineae) 3 in adriamycin-resistant Jeong et al. (2007) MCF-7/ADR cells 3,4,6-Trihydroxy-2,4- Onychium japonicum 3 in MCF-7/ADR and Bel-7402/5-Fu Li et al. (2011a) dimethoxy-3-(3,4- (Sinopteridaceae) cells dihydroxybenzyl) chalcone, and derivatives 3,5,4-Trimethoxy-trans- Dalea versicolor (Fabaceae) Enhances the antimicrobial effect of Belofsky et al. (2004) stilbene berberine against NorA S. aureus mutant strain Quinones, anthraquinones, naphthoquinones Aloe-emodin Rheum palmatum 2 Cui et al. (2008) (Polygonaceae); Aloe spp. (Asphodelaceae) Diospyrone (a Diospyros canaliculata Inhibits efflux pump in Kuete et al. (2010) naphthoquinone) (Ebenaceae) Gram-negative bacteria Emodin Rheum palmatum 2; synergistic antimicrobial effect Lee et al. (2010), Cui et al. (2008) (Polygonaceae) with ampicillin or oxacillin in MRSA Rhein Rheum palmatum 2, 4 Cui et al. (2008), van Gorkom et al. (Polygonaceae) (2002) Lignans Syringaresinol Sasa borealis (Gramineae) 1 in adriamycin-resistant Jeong et al. (2007) MCF-7/ADR cells Coumarins and furanocoumarins Bergamottin, Citrus hybrids (Rutaceae) 1 de Castro et al. (2007, 2008) 6,7-dihydroxybergamottin, 6,7-epoxybergamottin Alkaloids Acronycine Bauerella australiana 2 Dorr et al. (1989) Arborinine, evoxanthine Ruta graveolens (Rutaceae) 1, 5 in cancer cells Rethy et al. (2008) Berbamine Berberis sp. (Berberidaceae) 2 in BBB and in Caco2 cells He and Liu (2002) Berberine Hydrastis canadensis 1, 2, 2 in BBB; 8 (bacteria) 2 in Severina et al. (2001), He and Liu (Ranunculaceae) vascular smooth muscle cells (2002), Efferth et al. (2005), Suzuki (VSMCs) et al. (2010) Camptothecin Camptotheca acuminata Substrate for ABC2 transporter in Mattern et al. (1993), Leeetal. (Nyssaceae) Botrytis cinerea; for PMR5 in (2005), Nakaune et al. (2002), Penicillium digitatum, AtrBp in Andrade et al. (2000) Aspergillus nidulans;11 Canthin-6-one, Allium neapolitanum Inhibits Mycobacterium, O’Donnell and Gibbons (2007) 8-hydroxy-canthin-6-one, (Amaryllidaceae), methicillin-resistant Staphylococcus 5(zeta)-hydroxy-octadeca-6(E)- (Simaroubaceae), (Rutaceae) aureus (MRSA); and a MDR strain 8(Z)-dienoic of S. aureus acid Capsaicin Capsicum frutescens 2, 4 Okura et al. (2010) (Solanaceae) Catharanthine 2, 4 (vinblastine) in CEM/VLB1K Beck et al. (1988), Zamora et al. cells (1988)

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Table 2 | Continued

Natural product Occurrence Activities Reference

Cepharanthine Stephania cepharantha 4 (doxorubicin and vincristine) Ikeda et al. (2005), Katsui et al. (Menispermaceae) (2004), Nakajima et al. (2004) Chelerythrine Zanthoxylum clava-herculis Reversal of drug resistance in methicillin- Gibbons et al. (2003) (Rutaceae) resistant Staphylococcus aureus (MRSA) Cinchonine, hydrocinchonine, Cinchona pubescens (Rubiaceae) 4 Solary et al. (2000), Genne et al. quinidine (1994), Lee et al. (2011) Colcemid, colchicine Colchicum autumnale 2 Elsinga et al. (2004) (Colchicaceae) Conoduramine Peschiera laeta (Apocynaceae) 2, 4 in KB cells You et al. (1994) Coptisine Several species of 2 in vascular smooth muscle cells Suzuki et al. (2010) Ranunculaceae; Berberidaceae (VSMCs) 8-Oxocoptisine Coptis japonica (Ranunculaceae) 1 in MES-SA/DX5 and HCT15 cells Min et al. (2006b) Coronaridine, heyneanine Tabernanthe iboga 4 in vincristine-resistant KB cells Kam et al. (2004) dippinine B and C (Apocynaceae) Cycleanine Synclisia scabrida 6 in MCF-7/Adr and KBv200 cells Tian and Pan (1997) (Menispermaceae) Cyclopamine Veratrum spp. (Melanthiaceae) 1, 3 Lavie et al. (2001) Dauriporphine Sinomenium acutum 1 in MES-SA/DX5 and HCT15 cells Min et al. (2006a) (Menispermaceae) Emetine Psychotria ipecacuanha 2, 11 Möller et al. (2006) (Rubiaceae) Ergotamine Claviceps purpurea 1 in MDR cells Yasuda et al. (2002) (Clavicipitaceae) Fangchinoline Stephania tetrandra Reduces resistance to paclitaxel and Choi et al. (1998), Wang et al. (2005) (Menispermaceae) actinomycin D in HCT15 cells Galanthamine Galanthus nivalis 1 at the BBB Namanja et al. (2009) (Amaryllidaceae) Gamma-fagarine Phellodendron amurense 1 MDR cancer cells Min et al. (2007) (Rutaceae) Glaucine Glaucium flavum (Papaveraceae) 1, 2 Ma and Wink (2009) Harmine Peganum harmala 9 Ma and Wink (2010) (Zygophyllaceae) Homoharringtonine, Cephalotaxus harringtonia 2, 11 Zhou et al. (1995), Efferth et al. (2003) cephalotaxine (Cephalotaxaceae) Hydrastine Hydrastis canadensis 2 Etheridge et al. (2007) (Ranunculaceae) Ibogaine Tabernanthe iboga 5, 9 Tournier et al. (2010) (Apocynaceae) Indole-3-carbinol Many species of Brassicaceae Downregulation of upregulated P-gp; Arora and Shukla (2003) dietary adjuvant in MDR cancer treatment Insularine, insulanoline Antizoma miersiana 9 in MCF-7/Adr and KBv200 cells Tian and Pan (1997) (Menispermaceae) Kopsamine, pleiocarpine, Kopsia dasyrachis (Apocynaceae) 4 Kam et al. (1998) lahadinine A, kopsiflorine Lobeline Lobelia inflata (Campanulaceae) 4 in tumor cells Ma and Wink (2008) 5-Methoxyhydnocarpine, Hydnocarpus kurzii Inhibitor of NorA MDR pump in Stermitz et al. (2000a,b, 2001), Guz pheophorbide A (Flacourtiaceae), Berberis spp. Staphylococcus aureus et al. (2001) (Berberidaceae) N-trans-feruloyl Mirabilis jalapa (Nyctaginaceae) Inhibits growth of Staphylococcus aureus Michalet et al. (2007) 4-O-methyldopamine overexpressing the multidrug efflux transporter NorA

(Continued)

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Table 2 | Continued

Natural product Occurrence Activities Reference

Oxyberberine, canthin-6-one, Phellodendron amurense 1 in MDR cancer cells Min et al. (2007) 4-methoxy-N-methyl-2- (Rutaceae) quinolone, oxypalmatine Paclitaxel Taxus spp. (Taxaceae) 2 Distefano et al. (1997) Palmatine Several species of 2 in vascular smooth muscle cells Severina et al. (2001), Suzuki et al. Ranunculaceae; Berberidaceae (VSMCs); 8 (bacteria) (2010) Piperine Piper nigrum (Piperaceae) 1, 2, 3, 9 in cancer cells; inhibition Han et al. (2008), Bhardwaj et al. of overexpressed mycobacterial (2002), Li et al. (2011b), Sharma et al. putative efflux protein (Rv1258c) (2010) Quinine Cinchona pubescens (Rubiaceae) 2; 4 Genne et al. (1994), Zamora et al. (1988) Rescinnamine Rauvolfia serpentina 3 of vinblastine; induces MDR1 and Bhat et al. (1995) (Apocynaceae) p-gp expression Reserpine Rauvolfia serpentina 8 in bacteria; 3 in Beck et al. (1988), Gibbons and Udo (Apocynaceae) methicillin-resistant Staphylococcus (2000), Markham et al. (1999) aureus (MRSA) strains (NorA MDR pump); 2; 3 of vinblastine in CEM/VLB1K cells Roemerine Annona senegalensis 2; 4 You et al. (1995) (Annonaceae) Rutaecarpine Evodia rutaecarpa (Rutaceae) 6 in p-gp overexpressing Lee et al. (1995), Adams et al. (2007) CEM/ADR5000 cells Sanguinarine Sanguinaria canadensis 4 Ding et al. (2002), Weerasinghe et al. (Papaveraceae) (2006) Stemocurtisine, Stemona aphylla and S. burkillii P-gp modulator, enhance the Chanmahasathien et al. (2011) oxystemokerrine (Stemonaceae) cytotoxicity of vinblastine, paclitaxel, and doxorubicin in KB-V1 cells Tetrandrine Stephania tetrandra 1; reduces resistance to paclitaxel Choi et al. (1998), Xu et al. (2006), (Menispermaceae) and actinomycin D in HCT15 cells; 4 Zhu et al. (2005), Fu et al. (2002, in MDR mice; 6 (in vitro and in vivo); 2004) 4in cancer patients treated with doxorubicin, etoposide, and cytarabine Thaliblastine Thalictrum spp. (Ranunculaceae) Reverses MDR by decreasing the Chen and Waxman (1995), Chen overexpression of P-gp in et al. (1993, 1996) MCF-7/Adr cells Tomatidine Solanum lycopersicum 1,2 Lavie et al. (2001) (Solanaceae) Trisphaeridine, pretazettine, Several species of 1 and 3 in L5178 MDR mouse Zupko et al. (2009) 2-O-acetyllycorine, Amaryllidaceae lymphoma cells risperidone Vasicine acetate, 2-acetyl Adhatoda vasica. (Acanthaceae) Inhibit Mycobacterium tuberculosis Ignacimuthu and Shanmugam (2010) benzylamine and a MDR strain Veralosinine, veranigrine Veratrum lobelianum, Veratrum 1 and 3 against doxorubicin Ivanova et al. (2011) nigrum (Melanthiaceae) Vincristine, Vinblastine Catharanthus roseus 2; 2 in BBB; 11 He and Liu (2002), Hu et al. (1995) (Apocynaceae) Vindoline 2; reversal of vinblastine resistance Beck et al. (1988) in a MDR human leukemic cell line and CEM/VLB1K cells

(Continued)

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Table 2 | Continued

Natural product Occurrence Activities Reference

Voacamine Peschiera laeta, Peschiera 1, 2; 2 in BBB; reversal of You et al. (1994), Meschini et al. fuchsiaefolia (Apocynaceae) vinblastine; and doxorubicin (2003, 2005) resistance in MDR cancer cells by binding to P-glycoprotein Yohimbine Rauwolfia serpentina Reversal of vinblastine resistance in Zamora et al. (1988), Bhat et al. (Apocynaceae) a MDR human leukemic cell line (1995) and CEM/VLB 100 cells

Activities: 1: inhibits p-gp; 2: p-gp substrate; 3: reversal of MDR; 4: reversal of p-gp mediated MDR; 5: inhibition of MDR1 gene. 6: p-gp modulation in cancer cells; 7: induction of apoptosis; 8: substrate for ABC transporter; 9: blocks BCRP and increases in mitoxantrone accumulation; 10: MRP1 inhibitor; 11: induction of MDR overexpression.

Among the structurally heterogenous group of alkaloids, a they might be excellent candidates as reversal agents, both in large number of the more lipophilic substances from the classes chemotherapy and in agriculture. of isoquinoline, protoberberine, quinoline, indole, monoterpene We have focused on ABC transporters in this review. But as indole, and steroidal alkaloids (Table 2) can serve as substrates mentioned above, resistance can be due to other mechanisms whereas the more polar alkaloids with a tropane, quinolizidine, as well and is often multifactorial. Faria et al. (2011) and Kim piperidine, and pyrrolizidine skeleton do not bind to ABC trans- et al. (2007, 2010) have successfully employed thymol (a pheno- porters (Wink, 2007). Similar to the situation of terpenoids, the lic monoterpene), salicyl aldehyde, and the alkaloid berberine to active alkaloids probably function as competitive inhibitors of P- enhance the activity of fungicides in Candida, Aspergillus, Penicil- gp and BCRP in cancer cells, and NorA in bacteria and fungi lium, and Cryptococcus. These experimental data can be regarded (Table 2). as a proof of concept that plant secondary products can be interest- It is remarkable on the first sight that also quite a large ing candidates for chemosensitization (even if they not interfere number of more polar phenolic SM (phenolic acids, flavonoids, with ABC transporters) of pathogenic fungi in agriculture and catechins, chalcones, xanthones, stilbenes, anthocyanins, tan- food technology to improve the fungicidal activity of certain nins, anthraquinones, and naphthoquinones) inhibit P-gp, MRP1, fungicides. BCRP, and OATP in cancer cells with MDR. Some of them can reverse MDR when given in combination with cytotoxic agents CONCLUSION (Table 2). Bacteria and fungi appear to be sensitive as well (Guz This review summarizes the evidence that selected SM of plants et al., 2001; Falcao-Silva et al., 2009). Some of these pheno- can be interesting candidates to inhibit ABC transporters in lics are lipophilic enough to be competitive inhibitors of ABC MDR cancer cells or to chemosensitize pathogenic fungi and transporters. other microbes for treatment with antimicrobial agents. Whereas Polyphenols are exciting tethering compounds of proteins. lipophilic terpenoids and alkaloids appear to be substrates of P-gp, They can effectively interact directly with proteins by forming MRP1, or BCRP and thus competitive inhibitors, the more polar hydrogen and ionic bonds with amino acid side chains. They phenolic compounds (flavonoids, tannins, quinones) can bind to can thus interfere with the 3D structure of proteins (conforma- the transporter proteins and inhibit their activity by disturbing tion) and inhibit their activities (details in Wink, 2008b; Wink protein conformation. A combination of a cytotoxic agent, antibi- and Schimmer, 2010). We speculate therefore, that the inhibition otic, or fungicide with a natural chemosensitizer (not necessarily seen in polyphenols is caused by a direct binding and complex an inhibitor of ABC transporters) might provide an interesting formation (not necessarily the active side) of ABC transporters. strategy to overcome MDR in cancer patients and to improve Since many polyphenols have no or very low toxicity (e.g., many antibiotic or antifungal efficacy in medicine, agriculture, or food of them are ingredients of our food, such as flavonoids or tannins), industry.

REFERENCES silymarin, from bench to bed side. multiple flavonoids in combina- toxic compounds. Microbiology 146, Adams, M., Mahringer, A., Kunert, Anticancer Res. 26, 4457–4498. tion alter the ABCG2-mediated 1987–1997. O., Fricker, G., Efferth, T., and Ambudkar, S. V., Dey, S., Hrycyna, C. tissue distribution of mitox- Angelini, A., Di Ilio, C., Castellani, Bauer, R. (2007). Cytotoxicity and A., Ramachandra, M., Pastan, I., and antrone in mice. Pharm. Res. 28, M. L., Conti, P., and Cuccurullo, p-glycoprotein modulating effects of Gottesman, M. M. (1999). Biochem- 1090–1099. F. (2010). Modulation of multidrug quinolones and indoloquinazolines ical, cellular, and pharmacological Andrade, A. C., Del Sorbo, G., Van resistance p-glycoprotein activity by from the Chinese herb Evodia rutae- aspects of the multidrug transporter. Nistelrooy, J. G., and Waard, M. A. flavonoids and honokiol in human carpa. Planta Med. 73, 1554–1557. Annu. Rev. Pharmacol. Toxicol. 39, (2000). The ABC transporter AtrB doxorubicin- resistant sarcoma cells Agarwal, R., Agarwal, C., Ichikawa, 361–398. from Aspergillus nidulans mediates (MES-SA/DX-5), implications for H., Singh, R. P., and Aggarwal, B. An, G., Wu, F., and Morris, M. E. resistance to all major classes natural sedatives as chemosensi- B. (2006). Anticancer potential of (2011). 5,7-Dimethoxyflavone and of fungicides and some natural tizing agents in cancer therapy.

Frontiers in Microbiology | Fungi and Their Interactions April 2012 | Volume 3 | Article 130 | 10 Wink et al. Inhibition of ABC transporter

J. Biol. Regul. Homeost. Agents 24, Chanmahasathien, W., Ampasavate, C., Enhancing antibiotic activity,a strat- Biochem. Biophys. Res. Commun. 197–205. Greger, H., and Limtrakul, P. (2011). egytocontrolAcinetobacter infec- 189, 551–557. Annereau, J. P., Szakács, G., Tucker, C. J., Stemona alkaloids, from traditional tions. J. Antimicrob. Chemother. 64, de Wet, H., McIntosh, D. B., Con- Arciello, A., Cardarelli, C., Collins, J., Thai medicine, increase chemosen- 1203–1211. seil, G., Baubichon-Cortay, H., Krell, Grissom,S.,Zeeberg,B. R.,Reinhold, sitivity via P-glycoprotein-mediated Conseil, G., Baubichon-Cortay, H., T., Jault, J. M., Daskiewicz, J. W., Weinstein, J. N., Pommier, Y., multidrug resistance. Phytomedicine Dayan, G., Jault, J. M., Barron, D., B., Barron, D., and Di Pietro, Paules, R. S., and Gottesman, M. M. 18, 199–204. and Di Pietro, A. (1998). Flavonoids, A. (2001). Sequence requirements (2004). Analysis of ATP-binding cas- Chauffert, B., Pelletier, H., Corda, C., a class of modulators with bifunc- of the ATP-binding site within sette transporter expression in drug- Solary, E., Bedenne, L., Caillot, D., tional interactions at vicinal ATP- the C-terminal nucleotide-binding selected cell lines by a microarray and Martin, F. (1990). Potential and steroid-binding sites on mouse domain of mouse P-glycoprotein, dedicated to multidrug resistance. usefulness of quinine to circum- P-glycoprotein. Proc. Natl. Acad. Sci. structure-activity relationships for Mol. Pharmacol. 66, 1397–1405. vent the anthracycline resistance in U.S.A. 95, 9831–9836. flavonoid binding. Biochemistry 40, Arora, A., and Shukla, Y. (2003). Mod- clinical practice. Br. J. Cancer 62, Cooray, H. C., Janvilisri, T., van Veen, H. 10382–10391. ulation of vinca-alkaloid induced P- 395–397. W., Hladky, S. B., and Barrand, M. Ding, Z., Tang, S. C., Weerasinghe, P., glycoprotein expression by indole-3- Chen, G., Ramachandran, C., and Kris- A. (2004). Interaction of the breast Yang, X., Pater, A., and Liepins, A. carbinol. Cancer Lett. 189, 167–173. han, A. (1993). Thaliblastine, a cancer resistance protein with plant (2002). The alkaloid sanguinarine Beck, W. T., Cirtain, M. C., Glover, C. plant alkaloid, circumvents mul- polyphenols. Biochem. Biophys. Res. is effective against multidrug resis- J., Felsted, R. L., and Safa, A. R. tidrug resistance by direct binding Commun. 317, 269–275. tance in human cervical cells via (1988). Effects of indole alkaloids to P-glycoprotein. Cancer Res. 53, Critchfield, J. W., Welsh, C. J., Phang, bimodal cell death. Biochem. Phar- on multidrug resistance and labeling 2544–2547. J. M., and Yeh, G. C. (1994). Mod- macol. 63, 1415–1421. of P-glycoprotein by a photoaffinity Chen, G., Teicher, B. A., and Frei, ulation of adriamycin accumula- Distefano, M., Scambia, G., Ferlini, analog of vinblastine. Biochem. E. (1996). Differential interactions tion and efflux by flavonoids in C., Gaggini, C., De Vincenzo, R., Biophys. Res. Commun. 153, of Pgp inhibitor thaliblastine with HCT-15 colon cells. Activation of Riva, A., Bombardelli, E., Ojima, 959–966. adriamycin, etoposide, taxol and P-glycoprotein as a putative mech- I., Fattorossi, A., Panici, P. B., Belofsky, G., Percivill, D., Lewis, K., anthrapyrazole CI941 in sensi- anism. Biochem. Pharmacol. 48, and Mancuso, S. (1997). Anti- Tegos, G. P., and Ekart, J. (2004). tive and multidrug-resistant human 1437–1445. proliferative activity of a new class Phenolic metabolites of Dalea versi- MCF-7 breast cancer cells. Anti- Cui, X. R., Tsukada, M., Suzuki, N., of taxanes (14beta-hydroxy-10- color that enhance antibiotic activity cancer Res. 16, 3499–3505. Shimamura, T., Gao, L., Koyanagi, deacetylbaccatin III derivatives) against model pathogenic bacteria. J. Chen, G., and Waxman, D. J. (1995). J., Komada, F., and Saito, S. (2008). on multidrug-resistance-positive Nat. Prod. 67, 481–484. Complete reversal by thaliblastine Comparison of the cytotoxic activ- human cancer cells. Int. J. Cancer Berek,L.,Szabo,D.,Petri,I. B.,Shoyama, of 490-fold adriamycin resistance in ities of naturally occurring hydrox- 72, 844–850. Y., Lin, Y. H., and Molnar, J. (2001). multidrug-resistant (MDR) human yanthraquinones and hydroxynaph- Dorr, R. T., Liddil, J. D., Von Hoff, Effects of naturally occurring glu- breast cancer cells. Evidence that thoquinones. Eur. J. Med. Chem. 43, D. D., Soble, M., and Osborne, C. cosides, solasodine glucosides, gin- multiple biochemical changes in 1206–1215. K. (1989). Antitumor activity and senosides and parishin derivatives MDR cells need not correspond Dantzig, A. H., Law, K. L., Cao, J., murine pharmacokinetics of par- on multidrug resistance of lym- to multiple functional determinants and Starling, J. J. (2001). Reversal enteral acronycine. Cancer Res. 49, phoma cells and leukocyte func- for drug resistance. J. Pharmacol. of multidrug resistance by the P- 340–344. tions. In vivo 15, 151–156. Exp. Ther. 274, 1271–1277. glycoprotein modulator, LY335979, Duarte, N., Gyemant, N., Abreu, P. Bhardwaj, R. K., Glaeser, H., Becque- Chieli, E., Romiti, N., Rodeiro, I., and from the bench to the clinic. Curr. M., Molnar, J., and Ferreira, M. J. mont, L., Klotz, U., Gupta, S. K., Garrido, G. (2010). In vitro mod- Med. Chem. 8, 39–50. (2006). New macrocyclic lathyrane and Fromm, M. F. (2002). Piperine, ulation of ABCB1/P-glycoprotein Dantzig, A. H., Shepard, R. L., Cao, J., diterpenes, from Euphorbia lagascae, a major constituent of black pepper, expression by polyphenols from Law, K. L., Ehlhardt, W. J., Baugh- as inhibitors of multidrug resistance inhibits human P-glycoprotein and Mangifera indica. Chem. Biol. Inter- man,T.M.,Bumol,T.,and Starling,J. of tumour cells. Planta Med. 72, CYP3A4. J. Pharmacol. Exp. Ther. act. 186, 287–294. J. (1996). Reversal of P-glycoprotein- 162–168. 302, 645–650. Choi, C. H., Kang, G., and Min, Y. D. mediated multidrug resistance by a Duarte, N., Lage, H., Abrantes, M., Bhat, U. G., Winter, M. A., Pearce, H. L., (2003). Reversal of P-glycoprotein- potent cyclopropyldibenzosuberane and Ferreira, M. J. (2010). Phe- and Beck, W. T. (1995). A structure- mediated multidrug resistance by modulator, LY335979. Cancer Res. nolic compounds as selective anti- function relationship among reser- protopanaxatriol ginsenosides from 56, 4171–4179. neoplasic agents against multidrug- pine and yohimbine analogues in Korean red ginseng. Planta Med. 69, de Castro, W. V., Mertens-Talcott, S., resistant human cancer cells. Planta their ability to increase expression 235–240. Derendorf, H., and Butterweck, V. Med. 76, 975–980. of mdr1 and P-glycoprotein in a Choi, S. U., Park, S. H., Kim, K. H., (2007). Grapefruit juice-drug inter- Duarte, N., Ramalhete, C., Varga, A., human colon carcinoma cell line. Choi, E. J., Kim, S., Park, W. K., actions, grapefruit juice and its Molnar, J., and Ferreira, M. J. Mol. Pharmacol. 48, 682–689. Zhang, Y. H., Kim, H. S., Jung, N. components inhibit P-glycoprotein (2009). Multidrug resistance mod- Brooks, T. A., Minderman, H., P., and Lee, C. O. (1998). The bis- (ABCB1) mediated transport of tal- ulation and apoptosis induction of O’Loughlin, K. L., Pera, P., Ojima, benzylisoquinoline alkaloids,tetran- inolol in Caco-2 cells. J. Pharm. Sci. cancer cells by terpenic compounds I., Baer, M. R., and Bernacki, R. J. dine and fangchinoline, enhance the 96, 2808–2817. isolated from Euphorbia species. (2003). Taxane-basedreversal agents cytotoxicity of multidrug resistance- de Castro, W. V., Mertens-Talcott, S., Anticancer Res. 29, 4467–4472. modulate drug resistance mediated related drugs via modulation of P- Derendorf, H., and Butterweck, V. Efferth, T., Chen, Z., Kaina, B., and Ag, by P-glycoprotein, multidrug resis- glycoprotein. Anticancer Drugs 9, (2008). Effect of grapefruit juice, W. (2005). Molecular determinants tance protein, and breast cancer 255–261. naringin, naringenin, and berg- of response of tumor cells to berber- resistance protein. Mol. Cancer Ther. Chung, S. Y., Sung, M. K., Kim, N. H., amottin on the intestinal carrier- ine. Cancer Genomics Proteomics 2, 2, 1195–1205. Jang, J. O., Go, E. J., and Lee, H. J. mediated transport of talinolol in 115–123. Cavet, M. E., West, M., and Simmons, (2005). Inhibition of P-glycoprotein rats. J. Agric. Food Chem. 56, Efferth, T., Sauerbrey, A., Halatsch, M. N. L. (1996). Transport and epithe- by natural products in human breast 4840–4845. E., Ross, D. D., and Gebhart, E. lial secretion of the cardiac glycoside, cancer cells. Arch. Pharm. Res. 28, de Lannoy, I. A., and Silverman, M. (2003). Molecular modes of action digoxin, by human intestinal epithe- 823–828. (1992). The MDR1 gene product, P- of cephalotaxine and homoharring- lial (Caco-2) cells. Br. J. Pharmacol. Chusri, S., Villanueva, I., Voravuthikun- glycoprotein, mediates the transport tonine from the coniferous tree 118, 1389–1396. chai, S. P., and Davies, J. (2009). of the cardiac glycoside, digoxin. Cephalotaxus hainanensis in human

www.frontiersin.org April 2012 | Volume 3 | Article 130 | 11 Wink et al. Inhibition of ABC transporter

tumor cell lines. Naunyn Schmiede- in vitro and in xenografts derived multidrug-resistant cancer cells. C. (2005). Cepharanthine potently bergs Arch. Pharmacol. 367, 56–67. from human breast adenocarcinoma In vivo 19, 367–374. enhances the sensitivity of anti- El-Readi, M. Z., Hamdan, D., Farrag, N., MCF-7/adr cells. Eur. J. Cancer 38, Gyemant, N., Tanaka, M., Molnar, P., cancer agents in K562 cells. Cancer El-Shazly, A., and Wink, M. (2010). 418–426. Deli, J., Mandoky, L., and Mol- Sci. 96, 372–376. Inhibition of P-glycoprotein activ- Genne, P., Dimanche-Boitrel, M. T., nar, J. (2006), Reversal of multidrug Ingelman-Sundberg, M., and Gomez,A. ity by limonin and other secondary Mauvernay, R. Y., Gutierrez, G., resistance of cancer cells in vitro, (2010). The past, present and future metabolites from Citrus species Duchamp, O., Petit, J. M., Martin, modification of drug resistance by of pharmacoepigenomics. Pharma- in human colon and leukaemia F., and Chauffert, B. (1992). Cin- selected carotenoids. Anticancer Res. cogenomics 11, 625–662. cell lines. Eur. J. Pharmacol. 626, chonine, a potent efflux inhibitor to 26, 367–374. Ivanova, A., Serly, J., Christov, V., Stam- 139–145. circumvent anthracycline resistance Han, Y., Chin Tan, T. M., and Lim, boliyska, B., and Molnar, J. (2011). Elsinga, P. H., Hendrikse, N. H., in vivo. Cancer Res. 52, 2797–2801. L. Y. (2008). In vitro and in vivo Alkaloids derived from genus Ver- Bart, J., Vaalburg, W., and van Genne, P., Duchamp, O., Solary, E., evaluation of the effects of piper- atrum and Peganum of Mongo- Waarde, A. (2004). PET studies Pinard, D., Belon, J. P., Dimanche- ine on P-gp function and expres- lian origin as multidrug resistance on P-glycoprotein function in the Boitrel, M. T., and Chauffert, B. sion. Toxicol. Appl. Pharmacol. 230, inhibitors of cancer cells. Fitoterapia blood-brain barrier, how it affects (1994). Comparative effects of 283–289. 82, 570–575. uptake and binding of drugs within quinine and cinchonine in reversing He, L., and Liu, G. Q. (2002). Effects Ivanova, A., Serly, J., Dinchev, D., the CNS. Curr. Pharm. Des. 10, multidrug resistance on human of various principles from Chinese Ocsovszki, I., Kostova, I., and Mol- 1493–1503. leukemic cell line K562/ADM. herbal medicine on rhodamine123 nar, J. (2009). Screening of some Etheridge, A. S., Black, S. R., Patel, Leukemia 8, 160–164. accumulation in brain capillary saponins and phenolic components P. R., So, J., and Mathews, J. M. Gibbons, S., Leimkugel, J., Oluwatuyi, endothelial cells. Acta Pharmacol. of Tribulus terrestris and Smilax (2007). An in vitro evaluation of M., and Heinrich, M. (2003). Activ- Sin. 23, 591–596. excelsa as MDR modulators. In vivo cytochrome P450 inhibition and P- ity of Zanthoxylum clava-herculis Hebestreit, P., and Melzig, M. (2003). 23, 545–550. glycoprotein interaction with gold- extracts against multi-drug resistant Cytotoxic activity of the seeds from Jeong, Y. H., Chung, S. Y., Han, A. R., enseal, Ginkgo biloba, grape seed, methicillin-resistant Staphylococcus Agrostemma githago var. githago. Sung, M. K., Jang, D. S., Lee, J., milk thistle,and ginseng extracts and aureus (mdr-MRSA). Phytother. Res. Planta Med. 69, 921–925. Kwon, Y., Lee, H. J., and Seo, E. their constituents. Planta Med. 73, 17, 274–275. Hohmann, J., Molnar, J., Redei, D., K. (2007). P-glycoprotein inhibitory 731–741. Gibbons, S., and Udo, E. E. (2000). Evanics, F., Forgo, P., Kalman, A., activity of two phenolic compounds, Falcao-Silva, V. S., Silva, D. A., Souza The effect of reserpine, a modula- Argay, G., and Szabo, P. (2002). Dis- (-)-syringaresinol and tricin from Mde, F., and Siqueira-Junior, J. P. tor of multidrug efflux pumps, on covery and biological evaluation of Sasa borealis. Chem. Biodivers. 4, (2009). Modulation of drug resis- the in vitro activity of tetracycline a new family of potent modula- 12–16. tance in Staphylococcus aureus by against clinical isolates of methi- tors of multidrug resistance, rever- Kam, T. S., Sim, K. M., Pang, H. S., Koy- a kaempferol glycoside from Heris- cillin resistant Staphylococcus aureus sal of multidrug resistance of mouse ano, T., Hayashi, M., and Komiyama, santia tiubae (Malvaceae). Phytother. (MRSA) possessing the tet(K) deter- lymphoma cells by new natural jat- K. (2004). Cytotoxic effects and Res. 23, 1367–1370. minant. Phytother. Res. 14, 139–140. rophane diterpenoids isolated from reversal of multidrug resistance by Faria, N. C. G., Kim, J. H., Goncalves, L., Gillet, J. P., Efferth, T., Steinbach, D., Euphorbia species. J. Med. Chem. 45, ibogan and related indole alka- Martins,M.,Chan,K. L.,and,Camp- Hamels, J., de Longueville, F., Bert- 2425–2431. loids. Bioorg. Med. Chem. Lett. 14, bell, B. (2011). Enhanced activity of holet, V., and Remacle, J. (2004). Hou, X. L., Takahashi, K., Tanaka, 4487–4489. antifungal drugs using natural phe- Microarray-based detection of mul- K., Tougou, K., Qiu, F., Komatsu, Kam, T. S., Subramaniam, G., Sim, nolics against yeast strains of Can- tidrug resistance in human tumor K., and Azuma, J. (2008). Cur- K. M., Yoganathan, K., Koyano, dida and Cryptococcus. Lett. Appl. cells by expression profiling of ATP- cuma drugs and curcumin regulate T., Toyoshima, M., Rho, M. C., Micobiol. 5, 506–513. binding cassette transporter genes. the expression and function of P- Hayashi, M., and Komiyama, K. Fernandes, J., Castilho, R. O., da Costa, Cancer Res. 64, 8987–8993. gp in Caco-2 cells in completely (1998). Reversal of multidrug resis- M. R., Wagner-Souza, K., Coelho Gottesman, M. M. (2002). Mechanisms opposite ways. Int. J. Pharm. 358, tance (MDR) by aspidofractinine- Kaplan, M. A., and Gattass, C. R. of cancer drug resistance. Annu. Rev. 224–229. type indole alkaloids. Bioorg. Med. (2003). Pentacyclic triterpenes from Med. 53, 615–627. Hu, X. F., Slater, A., Wall, D. M., Kan- Chem. Lett. 8, 2769–2772. Chrysobalanaceae species, cytotoxi- Guengerich, F. P. (2001). Uncommon tharidis, P., Parkin, J. D., Cowman, Kars, M. D., Iseri, O. D., Gunduz, city on multidrug resistant and sen- P450-catalyzed reactions. Curr. Drug A., and Zalcberg, J. R. (1995). Rapid U., and Molnar, J. (2008). Rever- sitive leukemia cell lines. Cancer Lett. Metab. 2, 93–115. up-regulation of mdr1 expression sal of multidrug resistance by syn- 190, 165–169. Guo, X. L., Leng, P., Yang, Y., Yu, L. by anthracyclines in a classical thetic and natural compounds in Foster, B. C., Foster, M. S., Vanden- G., and Lou, H. X. (2008). Pla- multidrug-resistant cell line. Br. J. drug-resistant MCF-7 cell lines. hoek, S., Krantis,A., Budzinski, J. W., giochin E, a botanic-derived pheno- Cancer 71, 931–936. Chemotherapy 54, 194–200. Arnason, J. T., Gallicano, K. D., and lic compound, reverses fungal resis- Hyafil, F., Vergely, C., Du Vignaud, Kashiwada, Y., Nishimura, K., Kuri- Choudri, S. (2001). An in vitro eval- tance to fluconazole relating to the P., and Grand-Perret, T. (1993). moto, S., and Takaishi, Y. (2011). uation of human cytochrome P450 efflux pump. J. Appl. Microbiol. 104, In vitro and in vivo reversal of New 29-nor-cycloartanes with a 3,4- 3A4 and P-glycoprotein inhibition 831–838. multidrug resistance by GF120918, seco- and a novel 2,3-seco-structure by garlic. J. Pharm. Pharm. Sci. 4, Guz, N. R., Stermitz, F. R., Johnson, J. an acridonecarboxamide derivative. from the leaves of Sinocalycanthus 176–184. B., Beeson, T. D., Willen, S., Hsiang, Cancer Res. 53, 4595–4602. chinensis. Bioorg. Med. Chem. 19, Fu, L., Liang, Y., Deng, L., Ding, Y., J., and Lewis, K. (2001). Flavono- Ignacimuthu, S., and Shanmugam, N. 2790–2796. Chen, L., Ye, Y., Yang, X., and lignan and flavone inhibitors of (2010). Antimycobacterial activity Katsui, K., Kuroda, M., Wang, Y., Pan, Q. (2004). Characterization of a Staphylococcus aureus multidrug of two natural alkaloids, vasicine Komatsu, M., Himei, K., Takemoto, tetrandrine, a potent inhibitor of resistance pump, structure-activity acetate and 2-acetyl benzylamine, M., Akaki, S., Asaumi, J., Kanazawa, P-glycoprotein-mediated multidrug relationships. J. Med. Chem. 44, isolated from Indian shrub Adha- S., and Hiraki, Y. (2004). Cepha- resistance. Cancer Chemother. Phar- 261–268. toda vasica Nees. leaves. J. Biosci. 35, ranthine enhances adriamycin sensi- macol. 53, 349–356. Gyemant, N., Tanaka, M., Antus, S., 565–570. tivity by synergistically accelerating Fu, L. W., Zhang, Y. M., Liang, Y. J., Hohmann, J., Csuka, O., Man- Ikeda, R., Che, X. F., Yamaguchi, T., apoptosis for adriamycin-resistant Yang, X. P., and Pan, Q. C. (2002), doky, L., and Molnar, J. (2005). Ushiyama, M., Zheng, C. L., Oku- osteosarcoma cell lines, SaOS2-AR The multidrug resistance of tumour In vitro search for synergy between mura, H., Takeda, Y., Shibayama, and SaOS2 F-AR. Int. J. Oncol. 25, cells was reversed by tetrandrine flavonoids and epirubicin on Y., Nakamura, K., and Jeung, H. 47–56.

Frontiers in Microbiology | Fungi and Their Interactions April 2012 | Volume 3 | Article 130 | 12 Wink et al. Inhibition of ABC transporter

Kim, J. H., Campbell, B. C., Mahoney, Lee, S. Y., Rhee, Y. H., Jeong, S. J., Lee, enhances these effects in multidrug- Mei, Y., Qian, F., Wei, D., and Liu, J. N., Chan, K. L., and Molyneux, R. J. H. J., Jung, M. H., Kim, S. H., Lee, E. resistant K562/A02 cells. Mol. Cell. (2004). Reversal of cancer multidrug (2010). Chemosensitization of afla- O., and Ahn, K. S. (2011). Hydrocin- Biochem. 360, 253–260. resistance by green tea polyphenols. toxigenic fungi to antimycin A and chonine, cinchonine, and qiuinidine Ma,Y.,and Wink, M. (2008). Lobeline, a J. Pharm. Pharmacol. 56, 1307–1314. strobilurin using salicylaldehyde, a potentiate paclitaxel-induced cyto- piperidine alkaloid from Lobelia can Meschini, S., Marra, M., Calcabrini, volatile natural compound targeting toxicity and apoptosis via multidrug reverse P-gp dependent multidrug A., Federici, E., Galeffi, C., and cellular antioxidation system. Myco- resistance reversal in MES-SA/DX5 resistance in tumor cells. Phytomed- Arancia, G. (2003). Voacamine, a pathologia 171, 291–298. uterine sarcoma cells. Environ. Toxi- icine 15, 754–758. bisindolic alkaloid from Peschiera Kim, J. H., Campbell, B. C., Mahoney, col. 26, 424–431. Ma, Y., and Wink, M. (2009). “Reversal fuchsiaefolia, enhances the cytotoxic N., Chan, K. L., Molyneux, R. J., and Lee,Y.-J.,Yamamoto,K.,Hamamoto,H., of multidrug resistance (MDR) by effect of doxorubicin on multidrug- May, G. (2007). Enhanced activity of Nakaune, R., and Hibi, T. (2005). A the isoquinoline alkaloid glaucine,” resistant tumor cells. Int. J. Oncol. 23, strobilurin and fludioxonil by using novel ABC transporter gene ABC2 in Multiple Drug Resistance, eds A. 1505–1513. berberine and phenolic compounds involved in multidrug susceptibility Meszaros and G. Balogh (Haup- Meschini, S., Marra, M., Condello, M., to target fungal antioxidative stress but not pathogenicity in rice blast pauge: Nova Science Publishers), Calcabrini, A., Federici, E., Dupuis, response. Lett. Appl. Microbiol. 45, fungus, Magnaporthe grisea. Pestic. 1–19. M. L., Cianfriglia, M., and Arancia, 134–141. Biochem. Physiol. 81, 13–23. Ma, Y., and Wink, M. (2010). The beta- G. (2005). Voacamine, an alkaloid Kitagawa, S., Nabekura, T., Nakamura, Lee, Y. S., Kang, O. H., Choi, J. G., carboline alkaloid harmine inhibits extracted from Peschiera fuchsiaefo- Y., Takahashi, T., and Kashiwada, Y. Oh, Y. C., Keum, J. H., Kim, S. B., BCRP and can reverse resistance to lia, inhibits P-glycoprotein action in (2007). Inhibition of P-glycoprotein Jeong, G. S., Kim, Y. C., Shin, D. W., the anticancer drugs mitoxantrone multidrug-resistant tumor cells. Int. function by tannic acid and penta- and Kwon, D. Y. (2010). Synergis- and camptothecin. Phytother. Res. J. Oncol. 27, 1597–1603. galloylglucose. J. Pharm. Pharmacol. tic effect of emodin in combination 24, 146–149. Michalet, S., Cartier, G., David, B., 59, 965–969. with ampicillin or oxacillin against Madureira, A. M., Spengler, G., Mol- Mariotte, A. M., Dijoux-Franca, Kolaczkowski, M., Kolaczowska, A., methicillin-resistant Staphylococcus nar, A., Varga, A., Molnar, J., Abreu, M. G., Kaatz, G. W., Stavri, M., Luczynski, J., Witek, S., and Gof- aureus. Pharm. Biol. 48, 1285–1290. P. M., and Ferreira, M. J. (2004). and Gibbons, S. (2007). N - feau, A. (1998). In vivo character- Leslie, E. M., Mao, Q., Oleschuk, C. J., Effect of cycloartanes on reversal caffeoylphenalkylamide derivatives ization of the drug resistance pro- Deeley, R. G., and Cole, S. P. (2001). of multidrug resistance and apopto- as bacterial efflux pump inhibitors. file of the major ABC transporters Modulation of multidrug resistance sis induction on mouse lymphoma Bioorg. Med. Chem. Lett. 17, and other components of the yeast protein 1 (MRP1/ABCC1) transport cells. Anticancer Res. 24, 859–864. 1755–1758. pleiotropic drug resistance network. and ATPase activities by interac- Mahringer, A., and Fricker, G. (2010). Min, Y. D., Choi, S. U., and Lee, K. Microb. Drug Resist. 4, 143–158. tion with dietary flavonoids. Mol. BCRP at the blood-brain bar- R. (2006a). Aporphine alkaloids and Krishnamurthy, P., and Schuetz, J. D. Pharmacol. 59, 1171–1180. rier, genomic regulation by 17β- their reversal activity of multidrug (2006). Role of ABCG2/BCRP in Li, M. C.,Yao, Z., Takaishi,Y., Tang, S. A., estradiol. Mol. Pharm. 7, 1835–1847. resistance (MDR) from the stems biology and medicine. Annu. Rev. and Duan, H. Q. (2011a). Isolation Maliepaard, M., van Gastelen, M. A., and rhizomes of Sinomenium acu- Pharmacol. Toxicol. 46, 381–410. of novel phenolic compounds with Tohgo, A., Hausheer, F. H., van tum. Arch. Pharm. Res. 29, 627–632. Kuete, V., Ngameni, B., Tangmouo, J. multidrug resistance (MDR) rever- Waardenburg, R. C., de Jong, L. Min, Y. D., Yang, M. C., Lee, K. H., G., Bolla, J. M., Alibert-Franco, S., sal properties from Onychium japon- A., Pluim, D., Beijnen, J. H., and Kim, K. R., Choi, S. U., and Lee, Ngadjui, B. T., and Pages, J. M. icum. Chem. Biodivers. 8,1112–1120. Schellens, J. H. (2001). Circum- K. R. (2006b). Protoberberine alka- (2010). Efflux pumps are involved Li, S., Lei,Y., Jia,Y., Li, N., Wink, M., and vention of breast cancer resistance loids and their reversal activity of in the defense of Gram-negative Ma, Y. (2011b). Piperine, a piperi- protein (BCRP)-mediated resistance P-gp expressed multidrug resistance bacteria against the natural prod- dine alkaloid from Piper nigrum re- to camptothecins in vitro using (MDR) from the rhizome of Coptis ucts isobavachalcone and diospy- sensitizes P-gp, MRP1 and BCRP non-substrate drugs or the BCRP japonica Makino. Arch. Pharm. Res. rone. Antimicrob. Agents Chemother. dependent multidrug resistant can- inhibitor GF120918. Clin. Cancer 29,757–761. 54, 1749–1752. cer cells. Phytomedicine 19, 83–87. Res. 7, 935–941. Min, Y. D., Kwon, H. C., Yang, M. C., Kurimoto, S., Kashiwada, Y., Lee, K. Limtrakul, P., Chearwae, W., Shukla, Mao, Q., and Unadkat, J. D. (2005). Lee, K. H., Choi, S. U., and Lee, H., and Takaishi, Y. (2011a). Triter- S., Phisalphong, C., and Ambudkar, Role of the breast cancer resistance K. R. (2007). Isolation of limonoids penes and a triterpene glucoside S. V. (2007). Modulation of func- protein (ABCG2) in drug transport. and alkaloids from Phellodendron from Dysoxylum cumingianum. Phy- tion of three ABC drug transporters, AAPS J. 7, E118–E133. amurense and their multidrug resis- tochemistry 72, 2205–2211. P-glycoprotein (ABCB1), mitox- Markham, P. N., Westhaus, E., Kly- tance (MDR) reversal activity. Arch. Kurimoto, S., Kashiwada, Y., Morris- antrone resistance protein (ABCG2) achko, K., Johnson, M. E., and Ney- Pharm. Res. 30, 58–63. Natschke, S. L., Lee, K. H., and and multidrug resistance protein 1 fakh, A. A. (1999). Multiple novel Möller, M., Weiss, J., and Wink, M. Takaishi, Y. (2011b). Dyscusins A-C, (ABCC1) by tetrahydrocurcumin, a inhibitors of the NorA multidrug (2006). Reduction of cytotoxicity three new steroids from the leaves major metabolite of curcumin. Mol. transporter of Staphylococcus aureus. of the alkaloid emetine through P- of Dysoxylum cumingianum. Chem. Cell. Biochem. 296, 85–95. Antimicrob. Agents Chemother. 43, glycoprotein (MDR1/ABCB1) Pharm. Bull. 59, 1303–1306. Liu, D. F., Li, Y. P., Ou, T. M., Huang, 2404–2408. in human Caco-2 cells and Lavie, Y., Harel-Orbital, T., Gaffield, S. L., Gu, L. Q., Huang, M., and Martins, A., Vasas, A., Schelz, Z., leukaemia cell lines. Planta Med. 72, W., and Liscovitch, M. (2001). Huang, Z. S. (2009). Synthesis and Viveiros, M., Molnar, J., Hohmann, 1121–1126. Inhibitory effect of steroidal antimultidrug resistance evaluation J., and Amaral, L. (2010). Con- Molnár, J., Engi, H., Gyémánt, N., alkaloids on drug transport and of icariin and its derivatives. Bioorg. stituents of Carpobrotus edulis Schelz, Z., Spengler, G., Ocsovski, I., multidrug resistance in human Med. Chem. Lett. 19, 4237–4240. inhibit P-glycoprotein of MDR1- Szücs, M., Hohmann, J., Szabo, M., cancer cells. Anticancer Res. 21, Loo, T. W., and Clarke, D. M. (2005). transfected mouse lymphoma cells. and Tanács, L. (2008). “Multidrug 1189–1194. Recent progress in understanding Anticancer Res. 30, 829–835. resistance reversal in cancer cells by Lee, S. W., Hwang, B. Y.,Kim, S. E., Kim, the mechanism of P-glycoprotein- Mattern, M. R., Hofmann, G. A., Pol- selected carotenoids, flavonoids and H. M., Kim, Y. H., Lee, K. S., Lee, mediated drug efflux. J. Membr. Biol. sky, R. M., Funk, L. R., McCabe, anthocyanins,” in Bioactive Hetero- J. J., and Ro, J.-S. (1995). Isolation 206, 173–185. F. L., and Johnson, R. K. (1993). cycles VI, Vol. 15, ed. N. Motohashi of modulators for multidrug resis- Lu, J. J., Cai, Y. J., and Ding, J. (2012). In vitro and in vivo effects of clin- (Berlin: Springer), 133–159. [Topics tance from the fruits of Evodia offic- The short-time treatment with cur- ically important camptothecin ana- in Heterocyclic Chemistry]. inalis. Korean J. Physiol. Pharmacol. cumin sufficiently decreases cell via- logues on multidrug-resistant cells. Molnar, J., Gyemant, N., Mucsi, I., 26, 344–348. bility, induces apoptosis and copper Oncol. Res. 5, 467–474. Molnar, A., Szabo, M., Kortvelyesi,

www.frontiersin.org April 2012 | Volume 3 | Article 130 | 13 Wink et al. Inhibition of ABC transporter

T., Varga, A., Molnar, P., Toth, G. Tsuruo, T., and Sawada, Y. (2007). Schinkel, A. H., and Jonker, J. W. (2003). Stermitz, F. R., Tawara-Matsuda, J., (2004). Modulation of multidrug Effects of various methoxyflavones Mammalian drug efflux transporters Lorenz, P., Mueller, P., Zenewicz, resistance and apoptosis of cancer on vincristine uptake and multidrug of the ATP binding cassette (ABC) L., and Lewis, K. (2000b), 5- cells by selected carotenoids. In vivo resistance to vincristine in P-gp- family, an overview. Adv. Drug Deliv. Methoxyhydnocarpin-D and 18, 237–244. overexpressing K562/ADM cells. Rev. 55, 3–29. pheophorbide A, Berberis species Najar, I. A., Sachin, B. S., Sharma, S. Pharm. Res. 24, 1936–1943. Severina, I. I., Muntyan, M. S., Lewis, K., components that potentiate berber- C., Satti, N. K., Suri, K. A., and Okura, T., Ibe, M., Umegaki, K., Shi- and Skulachev, V. P. (2001). Trans- ine growth inhibition of resistant Johri, R. K. (2010). Modulation of nozuka, K., and Yamada, S. (2010). fer of cationic antibacterial agents Staphylococcus aureus. J. Nat. Prod. P-glycoprotein ATPase activity by Effects of dietary ingredients on berberine, palmatine, and benzalko- 63, 1146–1149. some phytoconstituents. Phytother. function and expression of P- nium through bimolecular planar Stermitz, F. R., Scriven, L. N., Tegos, G., Res. 24, 454–458. glycoprotein in human intestinal phospholipid film and Staphylococ- and Lewis, K. (2002). Two flavonols Nakajima, A., Yamamoto, Y., Taura, K., epithelial cells. Biol. Pharm. Bull. 33, cus aureus membrane. IUBMB Life from Artemisia annua which poten- Hata, K., Fukumoto, M., Uchinami, 255–259. 52, 321–324. tiate the activity of berberine and H., Yonezawa, K., and Yamaoka, Y. Ordway, D., Hohmann, J., Viveiros, M., Shapiro, A. B., and Ling, V. (1997). norfloxacin against a resistant strain (2004). Beneficial effect of cepha- Viveiros, A., Molnar, J., Leandro, Effect of quercetin on Hoechst 33342 of Staphylococcus aureus. Planta ranthine on overcoming drug- C., Arroz, M. J., Gracio, M. A., transport by purified and recon- Med. 68, 1140–1141. resistance of hepatocellular carci- and Amaral, L. (2003). Carpobro- stituted P-glycoprotein. Biochem. Suttana, W., Mankhetkorn, S., Poompi- noma. Int. J. Oncol. 24, 635–645. tus edulis methanol extract inhibits Pharmacol. 53, 587–596. mon, W., Palagani, A., Zhokhov, S., Nakaune, R. N., Hamamoto, H. H., the MDR efflux pumps, enhances Sharma, S., Kumar, M., Nargotra, Gerlo, S., Haegeman, G., and Berghe, Imada, J. I., Akutsu, K. A., and Hibi, killing of phagocytosed S. aureus A., Koul, S., and Khan, I. A. W.V.(2010). Differential chemosen- T. H. (2002). A novel ABC trans- and promotes immune modulation. (2010). Piperine as an inhibitor of sitization of P-glycoprotein overex- porter gene, is involved in multidrug Phytother. Res. 17, 512–519. Rv1258c, a putative multidrug efflux pressing K562/Adr cells by with- resistance in the phytopathogenic Perez-Victoria, J. M., Chiquero, M. J., pump of Mycobacterium tuberculo- aferin A and Siamois polyphenols. fungus Penicillium digitatum. Mol. Conseil, G., Dayan, G., Di Pietro, sis. J. Antimicrob. Chemother. 65, Mol. Cancer 9, 99. Genet. Genomics 267, 179–185. A., Barron, D., Castanys, S., and 1694–1701. Suzuki, H., Tanabe, H., Mizukami, H., Namanja, H. A., Emmert, D., Pires, Gamarro, F. (1999). Correlation Smith, E. C., Kaatz, G. W., Seo, S. and Inoue, M. (2010). Selective M. M., Hrycyna, C. A., and between the affinity of flavonoids M., Wareham, N., Williamson, E. regulation of multidrug resistance Chmielewski, J. (2009). Inhibition binding to the cytosolic site of Leish- M., and Gibbons, S. (2007). The protein in vascular smooth mus- of human P-glycoprotein transport mania tropica multidrug transporter phenolic diterpene totarol inhibits cle cells by the isoquinoline alka- and substrate binding using a galan- and their efficiency to revert parasite multidrug efflux pump activity in loid coptisine. Biol. Pharm. Bull. 33, tamine dimer. Biochem. Biophys. Res. resistance to daunomycin. Biochem- Staphylococcus aureus. Antimicrob. 677–682. Commun. 388, 672–676. istry 38, 1736–1743. Agents Chemother. 51, 4480–4483. Tang, S., Bremner, P., Kortenkamp, Nielsen, D., and Skovsgaard, T. (1992). Rethy, B., Hohmann, J., Minorics, R., Solary, E., Mannone, L., Moreau, D., A., Schlage, C., Gray, A. I., Gib- P-Glycoprotein as multidrug Varga, A., Ocsovszki, I., Molnar, J., Caillot, D., Casasnovas, R. O., Guy, bons, S., and Heinrich, M. (2003). transporter–acritical-review of Juhasz, K., Falkay, G., and Zupko, H., Grandjean, M., Wolf, J. E., Biflavonoids with cytotoxic and current multidrug resistant cell- I. (2008). Antitumour properties of Andre, F., and Fenaux, P. (2000). antibacterial activity from Ochna lines. Biochim. Biophys. Acta 1139, acridone alkaloids on a murine lym- Phase I study of cinchonine, a mul- macrocalyx. Planta Med. 69, 169–183. phoma cell line. Anticancer Res. 28, tidrug resistance reversing agent, 247–253. Nissler, L., Gebhardt, R., and Berger, 2737–2743. combined with the CHVP regimen Taur, J. S., and Rodriguez-Proteau, R. S. (2004). Flavonoid binding to Robert, J., and Jarry, C. (2003). Mul- in relapsed and refractory lympho- (2008). Effects of dietary flavonoids a multi-drug-resistance transporter tidrug resistance reversal agents. J. proliferative syndromes. Leukemia on the transport of cimetidine via protein, an STD-NMR study. Anal. Med. Chem. 46, 4805–4817. 14, 2085–2094. P-glycoprotein and cationic trans- Bioanal. Chem. 379, 1045–1049. Rocha Gda, G., Simoes, M., Lucio, K. Steffens, J. J., Pell, E. J., and Tien, porters in Caco-2 and LLC-PK1 cell Nooter, K., and Stoter, G. (1996). Mol- A., Oliveira, R. R., Coelho Kaplan, M. (1996). Mechanisms of fungicide models. Xenobiotica 38, 1536–1550. ecular mechanisms of multidrug M. A., and Gattass, C. R. (2007). resistance in phytopathogenic fungi. Tian,H.,and Pan,O. C. (1997). Modula- resistance in cancer chemotherapy. Natural triterpenoids from Cecropia Curr. Opin. Biotechnol. 7, 348–355. tion of multidrug resistance by three Pathol. Res. Pract. 192, 768–780. lyratiloba are cytotoxic to both Steinbach, D., Sell, W., Voigt, A., Her- bisbenzyl-isoquinolines in compari- O’Donnell, G., and Gibbons, S. sensitive and multidrug resistant mann, J., Zintl, F., and Sauerbrey, son with verapamil. Zhongguo Yao Li (2007). Antibacterial activity of leukemia cell lines. Bioorg. Med. A. (2002). BCRP gene expression Xue Bao 18, 455–458. two canthin-6-one alkaloids from Chem. 15, 7355–7360. is associated with a poor response Tournier, N., Chevillard, L., Megarbane, Allium neapolitanum. Phytother. Res. Rojas, R., Caviedes, L., Aponte, J. C., to remission induction therapy in B., Pirnay, S., Scherrmann, J. M., 21, 653–657. Vaisberg, A. J., Lewis, W. H., Lamas, childhood acute myeloid leukemia. and Decleves, X. (2010). Interac- Ofer, M., Langguth, P., and Spahn- G., Sarasara, C., Gilman, R. H., and Leukemia 16, 1443–1447. tion of drugs of abuse and main- Langguth, H. (2006). Bidirectional Hammond, G. B. (2006). Aegicerin, Stermitz, F. R., Beeson, T. D., Mueller, P. tenance treatments with human P- membrane transport, simulations the first oleanane triterpene with J., Hsiang, J., and Lewis, K. (2001). glycoprotein (ABCB1) and breast of transport inhibition in uptake wide-ranging antimycobacterial Staphylococcus aureus MDR efflux cancer resistance protein (ABCG2). studies explain data obtained with activity, isolated from Clavija pump inhibitors from a Berberis Int. J. Neuropsychopharmacol. 13, flavonoids. Eur. J. Pharm. Sci. 29, procera. J. Nat. Prod. 69, 845–846. and a Mahonia (sensu strictu) 905–915. 251–258. Scambia, G., Ranelletti, F. O., Panici, P. species. Biochem. Syst. Ecol. 29, Trompier, D., Baubichon-Cortay, H., Ofer, M., Wolffram, S., Koggel, A., B., De Vincenzo, R., Bonanno, G., 793–798. Chang,X. B.,Maitrejean,M.,Barron, Spahn-Langguth, H., and Langguth, Ferrandina, G., Piantelli, M., Bussa, Stermitz, F. R., Lorenz, P., Tawara, J. D., Riordon, J. R., and Di Pietro, A. P. (2005). Modulation of drug S., Rumi, C., and Cianfriglia, M. N., Zenewicz, L. A., and Lewis, (2003). Multiple flavonoid-binding transport by selected flavonoids: (1994). Quercetin potentiates the K. (2000a). Synergy in a med- sites within multidrug resistance involvement of P-gp and OCT? Eur. effect of adriamycin in a multidrug- icinal plant, antimicrobial action protein MRP1. Cell.Mol.LifeSci.60, J. Pharm. Sci. 25, 263–271. resistant MCF-7 human breast- of berberine potentiated by 5- 2164–2177. Ohtani, H., Ikegawa, T., Honda, cancer cell line, P-glycoprotein as a methoxyhydnocarpin, a multidrug Twentyman, P. R., and Blee- Y., Kohyama, N., Morimoto, S., possible target. Cancer Chemother. pump inhibitor. Proc. Natl. Acad. Sci. hen, N. M. (1991). Resistance Shoyama, Y., Juichi, M., Naito, M., Pharmacol. 34, 459–464. U.S.A. 97, 1433–1437. modification by PSC-833, a

Frontiers in Microbiology | Fungi and Their Interactions April 2012 | Volume 3 | Article 130 | 14 Wink et al. Inhibition of ABC transporter

novel non-immunosuppressive Wesolowska, O., Hendrich, A. B., Wink (Chichester: Wiley-Blackwell), Zhang, S., Yang, X., and Morris, M. cyclosporin. Eur. J. Cancer 27, Laniapietrzak, B., Wisniewski, J., 21–161. E. (2004). Flavonoids are inhibitors 1639–1642. Molnar, J., Ocsovszki, I., and Micha- Xu, W. L., Shen, H. L., Ao, Z. F., Chen, B. of breast cancer resistance protein van der Kolk, D. M.,Vellenga, E., Müller, lak, K. (2009). Perturbation of the A., Xia, W., Gao, F., and Zhang, Y. N. (ABCG2)-mediated transport. Mol. M., and De Vries, E. G. E. (1999). lipid phase of a membrane is not (2006). Combination of tetrandrine Pharmacol. 65, 1208–1216. Multidrug resistance protein MRP1, involved in the modulation of MRP1 as a potential-reversing agent with Zhao, M., Bai, L., Wang, L., Toki, glutathione, and related enzymes – transport activity by flavonoids. Cell. daunorubicin, etoposide and cytara- A., Hasegawa, T., Kikuchi, M., Abe, their importance in acute myeloid Mol. Biol. Lett. 14, 199–221. bine for the treatment of refrac- M., Sakai, J., Hasegawa, R., and leukemia. Adv. Exp. Med. Biol. 457, Wesolowska, O., Wisniewski, J., Duarte, tory and relapsed acute myelogenous Bai, Y. (2007). Bioactive cardeno- 187–198. N., Ferreira, M. J., and Micha- leukemia. Leuk. Res. 30, 407–413. lides from the stems and twigs of van Gorkom, B. A., Timmer-Bosscha, lak, K. (2007). Inhibition of MRP1 Yasuda, K., Lan, L. B., Sanglard, D., Nerium oleander. J. Nat. Prod. 70, H., de Jong, S., van der Kolk, D. transport activity by phenolic and Furuya, K., Schuetz, J. D., and 1098–1103. M., Kleibeuker, J. H., and de Vries, terpenic compounds isolated from Schuetz, E. G. (2002). Interaction of Zhou, D. C., Zittoun, R., and Marie, E. G. (2002). Cytotoxicity of rhein, Euphorbia species. Anticancer Res. cytochrome P450 3A inhibitors with J. P. (1995). Homoharringtonine, an the active metabolite of sennoside 27, 4127–4133. P-glycoprotein. J. Pharmacol. Exp. effective new natural product in can- laxatives, is reduced by multidrug Wijnholds,J.,deLange,E. C.,Scheffer,G. Ther. 303, 323–332. cer chemotherapy. Bull. Cancer 82, resistance-associated protein 1. Br. J. L., van den Berg, D. J., Mol, C. A., van Ye, J., Zheng, Y., and Liu, D. (2009). 987–995. Cancer 86, 1494–1500. derValk,M.,Schinkel,A. H.,Scheper, Reversal effect and its mechanism of Zhou, S., Lim, L. Y., and Chowbay, B. Versantvoort, C. H., Broxterman, H. J., R. J., Breimer, D. D., and Borst, P. ampelopsin on multidrug resistance (2004). Herbal modulation of P- Lankelma, J., Feller, N., and Pinedo, (2000). Multidrug resistance protein in K562/ADR cells. Zhongguo Zhong glycoprotein. Drug Metab. Rev. 36, H. M. (1994). Competitive inhibi- 1 protects the choroid plexus epithe- YaoZaZhi34, 761–765. 57–104. tion by genistein and ATP depen- lium and contributes to the blood- Yoo, H. H., Lee, M., Chung, H. J., Lee, S. Zhu, A., Wang, X., and Guo, Z. (2001). dence of daunorubicin transport in cerebrospinal fluid barrier. J. Clin. K., and Kim, D.-H. (2007). Effects Study of tea polyphenol as a rever- intact MRP overexpressing human Invest. 105, 279–285. of diosmin, a flavonoid glycoside sal agent for carcinoma cell lines’ small cell lung cancer cells. Biochem. Wink, M. (1988). Plant breeding: in citrus fruits, on P-glycoprotein- multidrug resistance (study of TP as Pharmacol. 48, 1129–1136. importance of plant secondary mediated drug efflux in human a MDR reversal agent). Nucl. Med. Versantvoort, C. H., Rhodes, T., and metabolites for protection against intestinal Caco-2 cells. J. Agric. Food Biol. 28, 735–740. Twentyman, P. R. (1996). Acceler- pathogens and herbivores. Theor. Chem. 55, 7620–7625. Zhu, X., Sui, M., and Fan, W. (2005). ation of MRP-associated efflux of Appl. Genet. 75, 225–233. Yoshida, N., Takagi, A., Kitazawa, H., In vitro and in vivo characteriza- rhodamine 123 by genistein and Wink, M. (1993). Allelochemical prop- Kawakami, J., and Adachi, I. (2005). tions of tetrandrine on the rever- related compounds. Br. J. Cancer 74, erties and the raison d’être of Inhibition of P-glycoprotein- sal of P-glycoprotein-mediated drug 1949–1954. alkaloids. Alkaloids Chem. Biol. 43, mediated transport by extracts of resistance to paclitaxel. Anticancer Wang, F. P., Wang, L., Yang, J. S., 1–118. and monoterpenoids contained in Res. 25, 1953–1962. Nomura, M., and Miyamoto, K. Wink, M. (2000). Interference of alka- Zanthoxyli fructus. Toxicol. Appl. Zupko, I., Rethy, B., Hohmann, J., (2005). Reversal of P-glycoprotein- loids with neuroreceptors and ion Pharmacol. 209, 167–173. Molnar, J., Ocsovszki, I., and dependent resistance to vinblas- channels. Nat. Prod. Res. 21, 3–129. You, G., and Morris, M. E. (2007). Drug Falkay, G. (2009). Antitumor activ- tine by newly synthesized bisben- Wink, M. (2003). Evolution of sec- Transporters- Molecular Characteri- ity of alkaloids derived from zylisoquinoline alkaloids in mouse ondary metabolites from an ecolog- zation and Role in Drug Disposition. Amaryllidaceae species. In vivo 23, leukemia P388 cells. Biol. Pharm. ical and molecular phylogenetic per- Hoboken, NJ: Wiley-Interscience. 41–48. Bull. 28, 1979–1982. spective. Phytochemistry 64, 3–19. You, M., Ma, X., Mukherjee, R., Wang, L., Bai, L., Nagasawa, T., Wink, M. (2007). Molecular modes of Farnsworth, N. R., Cordell, G. Conflict of Interest Statement: The Hasegawa, T., Yang, X., Sakai, J., action of cytotoxic alkaloids- from A., Kinghorn, A. D., and Pez- authors declare that the research was Bai, Y., Kataoka, T., Oka, S., and DNA intercalation, spindle poison- zuto, J. M. (1994). Indole alka- conducted in the absence of any com- Hirose, K. (2008). Bioactive triter- ing, topoisomerase inhibition to loids from Peschiera laeta that mercial or financial relationships that pene saponins from the roots of Phy- apoptosis and multiple drug resis- enhance vinblastine-mediated cyto- could be construed as a potential con- tolacca americana. J. Nat. Prod. 71, tance. Alkaloids Chem. Biol. 64,1–48. toxicity with multidrug-resistant flict of interest. 35–40. Wink, M. (2008a). Plant secondary cells. J. Nat. Prod. 57, 1517–1522. Watanabe, T., Tsuge, H., Oh-Hara, T., metabolism: diversity, function and You, M., Wickramaratne, D. B., Silva, Received: 12 January 2012; accepted: 19 Naito, M., and Tsuruo, T. (1995). its evolution. Nat. Prod. Commun. 3, G. L., Chai, H., Chagwedera, T. E., March 2012; published online: 23 April Comparative study on reversal effi- 1205–1216. Farnsworth, N. R., Cordell, G. A., 2012. cacy of SDZ PSC 833, cyclosporin Wink, M. (2008b). Evolutionary advan- Kinghorn, A. D., and Pezzuto, J. Citation: Wink M, Ashour ML and El- A and verapamil on multidrug resis- tage and molecular modes of M. (1995). (-)-Roemerine, an apor- Readi MZ (2012) Secondary metabolites tance in vitro and in vivo. Acta Oncol action of multi-component mix- phine alkaloid from Annona sene- from plants inhibiting ABC transporters 34, 235–241. tures used in phytomedicine. Curr. galensis that reverses the multidrug- and reversing resistance of cancer cells Weerasinghe, P., Hallock, S., Tang, S. Drug Metab. 9, 996–1009. resistance phenotype with cultured and microbes to cytotoxic and antimicro- C., Trump, B., and Liepins, A. Wink, M. (2010a). Functions and cells. J. Nat. Prod. 58, 598–604. bial agents. Front. Microbio. 3:130. doi: (2006). Sanguinarine overcomes P- Biotechnology of Plant Secondary Zamora, J. M., Pearce, H. L., and Beck, 10.3389/fmicb.2012.00130 glycoprotein-mediated multidrug- Metabolites – Annual Plant Reviews, W. T. (1988). Physical-chemical This article was submitted to Frontiers in resistance via induction of apop- Vol.39. Chichester: Wiley-Blackwell. properties shared by compounds Fungi and Their Interactions, a specialty tosis and oncosis in CEM-VLB Wink, M. (2010b). Biochemistry of Plant that modulate multidrug resistance of Frontiers in Microbiology. 1000 cells. Exp. Toxicol. Pathol. 58, Secondary Metabolism – Annual in human leukemic cells. Mol. Phar- Copyright © 2012 Wink, Ashour and 21–30. Plant Reviews, Vol. 40. Chichester: macol. 33, 454–462. El-Readi. This is an open-access article Wei, D., Mei, Y., and Liu, J. (2003). Wiley-Blackwell. Zhang, S., and Morris, M. E. (2003). distributed under the terms of the Cre- Quantification of doxorubicin and Wink, M., and Schimmer, O. (2010). Effects of the flavonoids biochanin ative Commons Attribution Non Com- validation of reversal effect of tea “Molecular modes of action of A, morin, phloretin, and silymarin mercial License, which permits non- polyphenols on multidrug resistance defensive secondary metabolites,” in on P-glycoprotein-mediated trans- commercial use, distribution, and repro- in human carcinoma cells. Biotech- Functions and Biotechnology of Plant port. J. Pharmacol. Exp. Ther. 304, duction in other forums, provided the nol. Lett. 25, 291–294. Secondary Metabolites,Vol.39,ed. M. 1258–1267. original authors and source are credited.

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