2534 Chiang Mai J. Sci. 2018; 45(7)

Chiang Mai J. Sci. 2018; 45(7) : 2534-2553 http://it.science.cmu.ac.th/ejournal/ Review

Triterpenoid Saponins of and Their Bioactivities Toshihiro Akihisa* [a], Masahiko Abe [a], Jiradej Manosroi [b,c,d] and Aranya Manosroi** [b,c,d,e] [a] Research Institute for Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan. [b] Faculty of Pharmacy, Chiang Mai University, and Division of Cosmetic Technology. [c] Faculty of Engineering and Technology, North Chiang Mai University, Chiang Mai 50200, Thailand. [d] Research Administration Center, Chiang Mai University, Chiang Mai 50200, Thailand. [e] Manose Health and Beauty Research Center 179 Moo 10, Liab Klong Chol Pratan Road, Suthep, Muang, Chiang Mai 50200, Thailand. *Author for correspondence; e-mail: [email protected] **Author for correspondence; e-mail: [email protected]

Received: 15 August 2016 Accepted: 9 October 2018

ABSTRACT Naturally occurring triterpenoid saponins reported in the plants of six genera, i.e., , , , , Tieghmella, and , of the family Sapotaceae are reviewed together with their biological activities. Most of the triterpenoid saponins found in these Sapotaceae plants are bisdesmosides with sugar chains at the C-3 and C-28 positions, and their aglycone is either protobassic acid, 16α-hydroxyprotobassic acid, bayogenin, or bassic acid, all belonging to the Δ12- series. The most frequently encountered sugar chain bound to C-3 of the aglycone is the single glucose residue (←Glu) followed by the dissaccharide chain of apiosyl-glucose (←Glc4←Api), while that attached to C-28 is the linear tetrasaccharide chain of rhamnosyl-xylosyl-rhamnosyl-arabinose (←Ara2←Rha4←Xyl3←Rha). Arganine C (16α-hydroxy Mi-saponin A) has been found to be the most common saponin of the Sapotaceae plants. The biological activities such as anti-inflammatory, cytotoxicity, antioxidant, melanogenesis-inhibitory, anti-tumor promoting, antiviral, and antifungal activities of these saponins are discussed.

Keywords: Sapotaceae, Argania spinosa, Madhuca , Mimusops species, Sideroxylon species, heckelii, Vitellaria paradoxa, triterpenoid saponin, phytochemistry, bioactivity Chiang Mai J. Sci. 2018; 45(7) 2535

1. INTRODUCTION During the course of our study on the Madhuca, Mimusops, Sideroxylon, Tieghmella, bioactive constituents from natural sources [1], and Vitellaria of the family Sapotaceae are we have demonstrated that the triterpenoid well studied for their chemical constituents saponins and other polar constituents from including triterpenoid saponins. The Vitellaria paradoxa of the family Sapotaceae triterpenoid saponins (including sapogenols) exhibit various biological activities such as found in the plants of Sapotacee possess melanogenesis-inhibitory, cytotoxic against hydroxylated Δ12-oleanane triterpenoid human cancer cells, and anti-inflammatory skeletons as aglycones, i.e., protobassic activities [2-4]. This prompted us to undertake acid (2β,3β,6β,23-tetrahydroxyolean-12-en- literature survey on the occurrence and 28-oic acid; I) (compounds 1-27), 16α- bioactivity of the triterpenoid saponin hydroxyprotobassic acid (2β,3β,6β,16α,23- constituents in the plants of the family pentahydroxyolean-12-en-28-oic acid; II) Sapotaceae. The triterpenoid saponins (compounds 28-58), bayogenin (2β,3β,23- of several plants belonging to the genera trihydroxyolean-12-en-28-oic acid or Argania, Madhuca, Mimusops, Sideroxylon, and 6-deoxyprotobassic acid; III) (compounds Tieghmella, as well as Vitellaria, have been 59-66), 2-oxouncargenin A (3β,6β,23- found to exhibit various bioactivities, and trihydroxy-2-oxoolean-12-en-28-oic acid; IV) this review summarizes the results gathered (compounds 67 and 68), bassic acid (2β,3β, on the triterpenoid saponin constituents of 23-trihydroxyoleana-5,12-dien-28-oic acid; these Sapotaceae plants and their bioactivities. V) (compounds 69-73), and The family Sapotaceae, which belongs (3β-hydroxyolean-12-en-28-oic acid; VI) to the order , is a largely tropical (compounds 74-76). Two sapogenols family of evergreen trees and shrubs. contained rearranged-oleanane skeletons, There are 53 genera (35-75, depending on VII (compound 77) and VIII (compound generic definition) and about 1,100 species 78), also have been detected in the in the family [5]. The order Ericales consists of Mimusops species (Table 1, Figure 1). These of 26 families with 11,000 species arranged saponins are the mono- or bisdesmosides into 347 genera, representing 6% of the of the aglycones with sugar chains at the C-3 global eudicot diversity [6]. Triterpenoids (bound to the aglycone by an O-heterosidic are commonly found in almost all studied linkage; R) and/or C-28 positions (bound Ericales, and the triterpenoid skeletal types to the aglycone by an ester linkage; R′). including oleanane, ursane, and lupane are The sugar chain at the C-3 is composed of found. One of the most important classes of one to three sugar residue(s) (R = B-L) while metabolites in the Ericales is represented by that at the C-28 position has one to six sugar the triterpenoid saponins, especially by the residue(s) (R′ = b-w). The sugar moieties oleanane-type, and their occurrence is very identified in these saponins are β-D- common in many families of this order [6]. apiofuranosyl (Api), α-L-arabinopyranosyl (Ara), β-D-glucopyranosyl (Glc), β-D- 2. TRITERPENOID SAPONINS AND glucuronopyranosyl (GlcA), 6-O-methyl SAPOGENOL CONSTITUENTS OF β-D-glucuronopyranosyl (MeGlcA), SAPOTACEAE α-L-rhamnopyranosyl (Rha), and β-D- Due to the economic importance in the xylopyranosyl (Xyl) groups (Table 2, tropical countries, plants of genera Argania, Figure 1). 2536 Chiang Mai J. Sci. 2018; 45(7)

Table 1. Triterpenoid saponins and sapogenols found in the Sapotaceae plants. Compounda) R R′ Sourceb) Reference Aglycone: Protobassic acid (I) 1 Protobassic acid A a Madhuca indica, leaf [25] Vitellaria paradoxa, seed kernel [38] 2 Madlongiside C A c Ma. longifolia, seed [23] 3 Madlongiside D A d Ma. longifolia, seed [23] 4 Sideroxyloside C A n Sideroxylon foetidissimum, root [34] 5 Mi- I B a Ma. longifolia, seed [23] S. cubense, root [36] V. paradoxa, seed kernel [38] 6 Mimusopside A B d Ma. longifolia, seed [23] , seed [29] 7 Mi-saponin A B i Argania spinosa, seed kernel [9] A. spinosa, seed shell (saponin 2) [11] Ma. butyracea, seed [16] Ma. longifolia, seed kernel [21] Mi. laurifolia, seed [27] 8 Arganine F B j A. spinosa, seed kernel [9] Ma. butyracea, seed (butyroside A) [16] 9 Sideroxyloside A B k Mi. laurifolia, leaf (saponin 15) [26] S. cubense, root [36] 10 Mimusopin B l Mi. elengi, seed [28] Mi. elengi, seed kernel (saponin 4) [30] 11 Mi-saponin B B m Ma. longifolia, seed kernel [21] 12 Mi-saponin C B q Ma. longifolia, seed kernel [22] 13 Saponin 2 B r Mi. laurifolia, leaf [26] S. foetidissimum, root (saponin 4) [35] 14 Saponin 3 B s Mi. laurifolia, leaf [26] 15 Sideroxyloside B B w S. foetidissimum, root [34] 16 3-O-β-D-GlcA protobassic acid C a V. paradoxa, seed kernel [38] 17 Butyroside C C j Ma. butyracea, seed [24] Mi. elengi, seed kernel [30] Mi. hexandra, seed kernel [30] Mi. manikara, seed kernel [30] Mi. laurifolia, seed [27] 18 Paradoxoside C D a V. paradoxa, seed kernel [38] 19 Paradoxoside D E a V. paradoxa, seed kernel [38] 20 Mimusopsin E i A. spinosa, seed shell (saponin 1) [11] A. spinosa, fruit pulp (saponin 18) [10] Mi. elengi, seed [28] Mi. elengi, seed kernel (saponin 6) [40] 21 Arganine N E l A. spinosa, seed shell (compound 4) [10,11] Chiang Mai J. Sci. 2018; 45(7) 2537

Table 1. Continued. Compounda) R R′ Sourceb) Reference 22 Arganine D F i A. spinosa, seed kernel [9] Mi. elengi, seed (mimusin) [24] Mi. laurifolia, seed [20] 23 Arganine E F j A. spinosa, seed kernel [9] 24 Madhucoside A G p Ma. indica, bark [19] 25 Saponin 12 I i Mi. laurifolia, leaf [26] 26 Saponin 11 I l Mi. laurifolia, leaf [26] 27 Madhucoside B I o Ma. indica, bark [19]

Aglycone: 16α-Hydroxyprotobassic acid (II) 28 16α-Hydroxyprotobassic acid A a V. paradoxa, seed kernel [38] 29 3-O-β-D-Glc B a Ma. butyracea, seed [25] 16α-hydroxyprotobassic acid V. paradoxa, seed kernel [38] 30 Mimusopside B B d Mi. elengi, seed [29] 31 Arganine C B i A. spinosa, seed kernel [9] (16α-hydroxy Mi-saponin A) Ma. butyracea, seed [16] Mi. elengi, seed kernel [30] (saponin 5) Mi. laurifolia, seed [27] , fruit [37] V. paradoxa, seed kernel [38] 32 Butyroside B B j Ma. butyracea, seed [16] 33 Saponin 5 B m S. foetidissimum, root [35] 34 Saponin 2 B r S. foetidissimum, root [35] 35 Saponin 1 B t Mi. laurifolia, leaf [26] 36 3-O-β-D-GlcA C a V. paradoxa, seed kernel [38] 16α-hydroxyprotobassic acid 37 Paradoxoside A C d V. paradoxa, seed kernel [38] 38 Paradoxoside B C f V. paradoxa, seed kernel [38] 39 Tieghemelin C i Mi. laurifolia, seeds [27] T. heckelii, fruit [37] V. paradoxa, seed kernel [38] 40 Butyroside D C j Ma. butyracea, seed [24] V. paradoxa, seed kernel [38] 41 Parkioside C C k V. paradoxa, root bark [2] 42 Arganine K E i A. spinosa, fruit pulp [10,12] Mi. laurifolia, seed (saponin 8) [27] 43 Arganine M E l A. spinosa, seed shell [10,11] (compound 3) 2538 Chiang Mai J. Sci. 2018; 45(7)

Table 1. Continued. Compounda) R R′ Sourceb) Reference 44 Arganine A F i A. spinosa, seed kernel [9] Mi. elengi, seed (elengin) [32] Mi. laurifolia, seed [27] 45 Arganine B F j A. spinosa, seed kernel [9] 46 Saponin 3 F m S. foetidissimum, root [35] 47 Saponin 1 F r S. foetidissimum, root [35] 48 Saponin 7 H i Mi. laurifolia, seed [27] 49 Saponin 5 H l Mi. laurifolia, leaf [26] 50 Saponin 6 H l Mi. laurifolia, root [35] 51 Saponin 6 H t Mi. laurifolia, leaf [26] 52 Saponin 7 H v Mi. laurifolia, leaf [26] 53 Saponin 9 I i Mi. laurifolia, leaf [26] 54 Saponin 8 I l Mi. laurifolia, leaf [26] 55 Saponin 10 I t Mi. laurifolia, leaf [26] 56 Saponin 9 K i Mi. laurifolia, seed [27] 57 Saponin 13 L l Mi. laurifolia, leaf [26] 58 Saponin 14 L t Mi. laurifolia, leaf [26]

Aglycone: Bayogenin (III) 59 Arganine G I b A. spinosa, trunk [13] 60 Arganine H I c A. spinosa, trunk [13] 61 Arganine R J f A. spinosa, bark [14] 62 Arganine J I j A. spinosa, trunk [13] 63 Arganine Q J a A. spinosa, bark [14] 64 Arganine P J c A. spinosa, bark [14] 65 Arganine O J e A. spinosa, bark [14] 66 Arganine L J j A. spinosa, bark [14]

Aglycone: 2-Oxouncargenin A (IV) 67 Madlongiside A A c Ma. longifolia, seed [23] 68 Madlongiside B B c Ma. longifolia, seed [23]

Aglycone: Bassic acid (V) 69 Bassic acid A a V. paradoxa, seed kernel [38] 70 3-O-β-D-Glc bassic acid B a V. paradoxa, seed kernel [38] 71 Paradoxoside E D a V. paradoxa, seed kernel [38] 72 Saponin Ac) B a Ma. indica, seed [20] 73 Saponin Bc) B g Ma. indica, seed [20]

Aglycone: Oleanolic acid (VI) 74 Androseptoside A B a V. paradoxa, root bark [2] Chiang Mai J. Sci. 2018; 45(7) 2539

Table 1. Continued. Compounda) R R′ Sourceb) Reference 75 Parkioside A B h V. paradoxa, root bark [2] 76 Parkioside B H u V. paradoxa, root bark [2]

Aglycone: Mimusopic acid ( VII) 77 Mimusopic acid A a Mi. elengi, seed [33]

Aglycone: Mimusopsic acid (VIII) 78 Mimusopsic acid A a Mi. elengi, seed [33] a) Glc = glucopyranosyl; GlcA = glucuronopyranosyl. b) A.: Argania; Ma.: Madhuca; Mi.: Mimusops; S.: Sideroxylon; T.: Tieghemella; V.: Vitellaria. c) 2-O-β-D-Glc-V.

Table 2. The sugar residue abbreviations of triterpenoid saponins.

R (3β-O) R′ (28-O) A H a H B ←Glc b ←Glc C ←GlcA c ←Ara D ←MeGlcA d ←Ara2←Rha E ←Glc3←Glc e ←Ara4←Xyl F ←Glc6←Glc f ←Ara2←Rha4←Xyl G ←Glc2←Api g ←Ara2←Xyl4←Rha H ←Glc3←Api h ←Xyl2←Rha4←Xyl I ←Glc4←Api i ←Ara2←Rha4←Xyl3←Rha J ←GlcA4←Xyl j ←Ara2←Rha4←Xyl3←Api K ←Glc6←Glc6←Glc k ←Xyl2←Rha4←Xyl3←Rha L ←Glc(3←Rha)4←Api l ←Ara2←Rha(3←Rha)4←Xyl3!Rha m ←Ara2←Rha(3←Api)4←Xyl3←Rha n ←Ara2←Rha(3←Api)4←Rha4←Xyl o ←Ara2←Rha3←Glc(2←Xyl)4←Rha p ←Ara2←Rha2←Xyl(2←Api)3←Rha q ←Ara2←Rha4←Xyl(4←Glc)3←Rha r ←Ara2←Rha4←Xyl(4←Xyl)3←Rha s ←Xyl2←Rha4←Xyl(4←Xyl)3←Rha t ←Xyl2←Rha(3←Rha)4←Xyl3←Rha u ←Xyl2←Rha(3←Rha)4←Xyl3←Api v ←Xyl2←Rha4←Xyl(3←Rha)4←Xyl w ←Ara2←Rha(3←Api) 4←Rha4←Xyl3←Api 2540 Chiang Mai J. Sci. 2018; 45(7)

Figure 1. Triterpenoid saponins and sapogenols in Sapotaceae plants.

Extraction, isolation, and structure defatted materials were then treated with elucidation of triterpenoid saponins from methanol (MeOH) in order to isolate plant material can be performed by the the soluble hydrophilic components. The following way which represents the case MeOH extract was fractionated into ethyl for Vitellaria paradoxa [2]. Dried and acetate-, n-butanol-, and water-soluble pulverized plant materials were treated with fractions. All three fractions from the MeOH hexane to remove the lipid fraction, and the extract were subjected to successive column Chiang Mai J. Sci. 2018; 45(7) 2541

chromatography on Diaion HP-20, silica gel, mixture is about 4% [93]. Argan seed shell octadecyl silica gel, and Sephadex LH-20 [9-10] and argan fruit pulp [9,11] also contain columns, and to reversed-phase HPLC bisdesmosides of aglycone I (7, 20, 21, and which led to the isolation of triterpenoid 43) or II (7 and 42). All argan press-cake, seed saponins. Known compounds were identified shell, and fruit pulp contain saponin 7 as a by comparison of MS, 1H NMR, and 13C common constituent. Three saponins, 59, 60, NMR spectroscopic data with corresponding and 62, in the trunk [12], and five saponins, literature data. The structures of new 61 and 63-66, in the bark [13] of the argan compounds were elucidated on the basis of tree have been identified. All of these eight spectroscopic data by comparison with saponins share an identical aglycone named literature, and their proposed structures bayogenin (III). The argan bark contains were supported by analysis of various nearly 5% of saponins [9]. two-dimensional NMR data. While the sugar chain at C-3 is composed of one (B) or two glucose residue(s) (E, F) 3. ARGANIA SPINOSA for the saponins of the argan press-cake, The argan tree (Argania spinosa (L.) Skeels) seed shell, and fruit pulp, the sugar chain of is endemic in Southwestern Algeria and bark and trunk saponins is composed of Morocco. It grows on the west side of the two sugar residues, I (←Glc4←Api) or J high Atlas mountains. The fruit of A. spinosa (←GlcA4←Xyl). The second sugar chain at has an oleaginous kernel from which a C-28 of the saponins of the argan press-cake, well-known argan oil is prepared. Argan oil seed shell, and fruit pulp is composed of is nowadays a major and internationally four sugar residues in the linear form (i, j) well-established edible and cosmetic oil in or branched pentaglycosidic unit (l). On the the markets [7]. A large diversity of secondary other hand, the bark and trunk saponins metabolites including triterpenoids, , contain non- (a) or lower-glycosylated , volatile compounds, , (b, c, e, f) chain, in addition to the four and saponins has been isolated from various sugar residues (j), at C-28. parts of the argan tree. The argan press-cake (the by-product 4. MADHUCA SPECIES obtained from the preparation of argan oil The genus Madhuca is native to South, from argan seed kernel) has the saponin East, and Southeast Asia and Papuasia contents that have been identified as seven (from India to China to New ). bisdesmosidic saponins whose aglycone is Three species of this genus, i.e., Madhuca either protobassic acid (I) [Mi-saponin A (7), longifolia L., M. butyracea (Roxb.) Macbride, and arganine F (8), arganine D (22), and arganine M. indica J. F. Gmel, have been investigated E (23)] or 16α-hydroxyprotobassic acid (II) for their saponin constituents. M. longifolia [arganine C (31), arganine A (44), and arganine seeds are of economic importance as they B (45)] [8]. The saponin content in the fresh are good source of edible . Conventionally, argan seed kernels is 0.5%, of which 40% is M. longifolia has been used to treat infections, composed of 44. Saponin 45 is the second wounds, rheumatism, heart disease, diabetes, main saponin (about 8% of the crude saponin and many other disorders. This plant is extract) present in the argan press-cake. reported to contain triterpenoids, , The individual amount of other five saponins, saponins, flavonoids, and [14]. 7, 8, 22, 23, and 31, in the crude saponin M. butyracea contains , flavonoids, 2542 Chiang Mai J. Sci. 2018; 45(7)

triterpenoids and saponins, which have distributed throughout the greater part of anti-inflammatory and spermicidal activities India, and are reported to be used in [15]. M. indica (syn. M. latifolia, latifolia) Indian due to their is a tree widely distributed throughout India. anthelmintic, tonic, and astringent activities Its bark is traditionally used for the treatment [25]. Four Mimusops species, i.e., M. laurifolia, of rheumatism, ulcers, tonsillitis, and diabetes M. elengi, M. hexandra, and M. manikara, have mellitus, while its oil-free seed-cake is used been reported to contain triterpenoids and as insecticide. This plant has been reported saponins. to contain various sterols, esters of All saponins found in the plants of acids, and phenolic compounds along with Mimusops species possess I or II as aglycone. saponins [16-19]. Nine bisdesmosidic saponins have been Most saponins found in Madhuca species isolated from the seeds of M. laurifolia of which contain I or II as aglycone. Seven saponins, three (7, 17, and 22) contain I as aglycone, 2, 3, 5, 6, 7, 11, and 12, from M. longifolia while the other six (31, 39, 42, 44, 48, and 56) seeds [20-22], three saponins, 7, 8, and 17, possess II as aglycone [26]. Leaves of from seeds of M. butyracea [15, 23], and two M. latifolia contain fourteen saponins including saponins, 24 and 27, from M. indica, possess five bisdesmosides of I (9, 13, 14, 25, and 26) I as aglycone, and four saponins, 29, 31, 32, and nine bisdesmosides of II (35, 49, 51-55, and 40, from seeds of M. indica [19] possess 57, and 58) [25]. Seeds and seed kernels of II as aglycone. Seeds of M. longifolia M. elengi [27-31], M. hexandra and M. manikara contain two saponins, 67 and 68, which [27] also have been reported to contain possess 2-oxouncargenin A (IV) as aglycone bisdesmosides of I (6, 10, 17, 20, and 22) [22]. Seeds of M. indica have been reported and II (30, 31, and 44). Seeds of M. elengi to contain 2,3-bis-O-glycosylated (72) and have been further reported to contain 2,3,28-tris-O-glycosylated saponins (73) having two sapogenols, 77 and 78, with a migrated- V as aglycone [18]. oleanane (mimusopane) skeleton (VII and The C-3 position of all Madhuca VIII) [32]. saponins is unglycosylated (A) or only The sugar chain at C-3 of all Mimusops monoglycosylated (B or C) except for the saponins is composed of one (B, C) or two two saponins, 24 and 27, from the bark of sugar residue(s) (E, F, H, I) except for the M. indica [19], which contain apiosyl-glucosyl three saponins. Saponin 56 contains linear (G and I, respectively) sugar residue at C-3. trisaccharide units (K), and saponins 57 While the four saponins, 11 and 12 from and 58 possess branched three saccharide M. longifolia seeds, and 24 and 27 from M. indica units (L) as the sugar chain at C-3 which is a bark, contain the branched five sugar unique feature for Sapotaceae saponins. residues (m, o, p, or q) at C-28, other Madhuca While all nine saponins of seeds or seed kernels saponins (including one sapongenol [24]) of M. laurifolia contain sugar chains of possess no sugar (1, 5, 29, and 72), one sugar common tetrasaccharide unit at C-28 (i, j), (2, 67, and 68), linear three sugar (73), or most of those of the leaves of this plant linear four sugar (7, 8, 17, 29, 31, 32, and 40) were composed of branched pentaglycosidic residue at C-28. unit (l, r, s, t, v). The sugar chains at C-28 of the seed and seed kernel saponins of 5. MIMUSOPS SPECIES M. elengi are combined with two (d), four (i, Plants of Mimusops species are widely j), or branched five (l) sugar residues. Since Chiang Mai J. Sci. 2018; 45(7) 2543

butyroside C (17) has been found in all seeds of II, have been isolated from the fruits of or seed kernels of M. laurifolia, M. elengi, T. heckelii [36]. M. hexandra, and M. maikara, this saponin seems to be a common constituent in seeds 8. VITELLARIA PARADOXA or seed kernels of Mimusops species. The shea tree Vitellaria paradoxa C.F. Gaertner (syn. Butyrospermum paradoxum 6. SIDEROXYLON SPECIES (C.F. Gaertn.) Hepper, Butyrospermum parkii The genus Sideroxylon is native to mainly (G. Don) Kotschy) is indigenous to the warmer regions of North and South America. Savanna belt extending across sub-Saharan and pharmacological studies North of the equator, ranging from of Sideroxylon are limited, and only a few in the West to and species have been investigated. S. foetidissimum in the East [2, 38]. Its fruit is edible and Jacq. is a small to medium sized evergreen nutritious. The most widely valued product tree found in the West Indies from Cuba of shea tree is , the edible fat to Grenada [33]. The fruits of this species extracted from the seed kernel. In addition, are edible. Local people use this plant for shea butter is increasingly popular as medicinal purposes, although no detail is components of skin care products and available on its preparation or application cosmetic product formulations, in part due [34]. S. cubense (Greiseb.) T. Pennington is a to the unusually high level of non-saponifiable Caribbean species whose root is used lipid constituents in its fat [35, 38]. The externally in vernacular medicine to treat methanolic extract of the defatted kernels fractures [35]. [2] and the butanolic extract of the root The roots of S. foetidissinum and S. cubense bark of V. paradoxa [37] have so far been have been reported to contain eight (4, 13, 15, investigated for their saponin constituents. 33, 34, 46, 47, and 50) [33-34], and two The methanolic extract of the defatted (5 and 9) [35] saponins, respectively. All seed kernels of V. paradoxa has been shown saponins possess I or II as aglycone. While to contain fourteen saponins, including most of these saponins are bisdesmosides, five (1, 5, 16, 18, and 19), nine (28, 29, 31, sideroxyloside C (4) from S. foetisissimum, and and 36-41), and two (70 and 71) saponins Mi-glycoside I (5) from S. cubense are the containing I, II, and bassic acid (V), monodesmosides without sugar chain at respectively, as aglycones, in addition to C-3 and C-28, respectively. Sideroxiloside the three sapogenols, 1, 28, and 69 [2]. B (15) from S. foetidissimum contains the It might be noted that 69 itself or its side-chain of branched six sugar residues (w) derivatives are suggested not to be at C-28. This is the unique structural feature genuinely natural, but dehydration products since no other Sapotaceae species contains of 1 [26, 39]. Most saponins of the seed such a saponin. kernels of V. paradoxa are found to be less glycosylated when compared with those 7. TIEGHEMELLA HECKELII of other Sapotaceae species mentioned Tieghemella heckelii Pierre ex A. Chev. is a above. Thus, among the fourteen saponins, large tree found in West African rain forest. eight [Mi-glycoside I (5), 3-O-β-D- Many parts of the tree are used in traditional glucuronopyranosyl protobassic acid medicine [36]. Both arganine C (31) and (16), paradoxoside C (18), paradoxoside tieghemelin (39), which are the bisdesmosides D (19), 3-O-β-D-glucopyranosyl 16α- 2544 Chiang Mai J. Sci. 2018; 45(7)

hydroxyprotobassic acid (29), 3-O-β-D- sequence Glc-aglycone-Ara-Rha-Xyl-Rha glucuronopyranosyl 16α-hydroxyprotobassic or Glc-aglycone-Ara-Rha-Xyl-Api might acid (36), 3-O-β-D-glucopyranosyl bassic acid represent a chemotaxonomic marker of the (70), and paradoxoside E (71)] are the 3β-O- family Sapotaceae although the four-sugar monodesimosides, and, except for the three core i at C-28 is also a common unit in saponins (18, 19, and 71), all possess one saponins from species of the Asteraceae, sugar residue (B or C) at C-3. The methanolic Verbenaceae, Lamiaceae, and Cucurbitaceae extracts of the defatted shea kernels from families [43]. seven sub-Saharan countries have been Within the family Sapotaceae, Madhuca reported to contain 4.9-35.2% of triterpenoid spp., Mimusops spp., and Tieghemlla heckelii saponins along with sugars (25.6-80.2%) and can be characterized by the predominance minor amounts of cucurbates (1.0-21.0%) of the saponins with the one-sugar core, and phenolic compounds (0.3-16.0%) [4]. B [or GlcA (C)], at C-3, and the four-sugar The root bark of V. paradoxa has been core, i or j, at C-28, while Argania spinosa reported to contain three saponins contained saponins with two-sugar core, possessing oleanolic acid (VI) as aglycone, Glc-Glc (E or F), at C-3, and the four-sugar of which two, parkioside A (75) and core, i or j, at C-28, as the predominant parkioside B (76), are bisdesmosides, and saponins. On the other hand, Sideroxylon spp. the other one, androseptoside A (74), is is characteristic by the predominance of the 3β-O-monodesmoside [37]. saponins with one-sugar core, B, at C-3, and five-sugar core, Ara-Rha-Xyl(Xyl)-Rha (r), 9. CHEMOTAXONOMIC SIGNIFICANCE OF at C-28, and Vitellaria paradoxa by the SAPOTACEAE TRITERPENOID SAPONINS saponins with one-sugar core, B or C, at C-3, The set of saponins from the Sapotaceae and no-sugar core, H (a), at C-28. plant species surveyed in this article The family Sapotaceae belongs to the all contain protobassic acid (I) and clade Primuloids of the order Ericales. 16α-hydroxyprotobassic acid (II) as Although flavonoids and were aglycones which may be considered as a characterized as good taxonomic markers chemical marker of the species belonging for the order, triterpenoid saponins are to Sapotaceae, especially of the seed part stated to be the markers for the family [25-27]. Occurrence of these saponins in rather than for Sapotaceae the other plant families is very restricted, and other plant families within Primuloids and only some species of clade [6]. (order Caryophyllales) [40] and Rubiaceae (order Gentianales) [41, 42] have been 10. BIOACTIVITIES OF TRITERPENOID reported to contain saponins of protobassic SAPONINS FROM SAPOTACEAE acid and 16α-hydroxyprotobassic acid, The extracts and preparations of various respectively. parts of the Sapotaceae plants described in The one-sugar core, Glc (B), followed this article have been used as traditional by the two-sugar core, Glc-Api (H or I), medicines. Since triterpenoid saponins have at C-3, and the four-sugar core, Ara-Rha-Xyl- been proved to possess a wide range of Rha (i) followed by Ara-Rha-Xyl-Api (j), biological and pharmacological activities, at C-28, are detected most frequently in these compounds seem to be responsible, the Sapotaceae saponins, and the saponin in part, for the bioactivity of the extracts Chiang Mai J. Sci. 2018; 45(7) 2545

and preparations of Sapotaceae plants. from the seed cake left after oil extraction. In this section, we summarized the major The saponins of Mimusops fruits have also biological activities reported for the saponin been reported to possess anti-inflammatory fractions and individual saponins of the activity [25, 46]. Sapotaceae plants. Ten glycosylated and two unglycosylated oleanolic acid derivatives, i.e., 5, 16, 18, 19, 11. ANTI-INFLAMMATORY ACTIVITY 31, 37, 38, 39, 40, and 70, and 1 and 69, The anti-inflammatory properties of respectively, isolated from the methanolic saponins of the argan press-cakes have been extract of the defatted shea kernels, have been evaluated using oedema due to carrageenan evaluated for anti-inflammatory activities or experimental trauma in rats with oral against 12-O-teradecanoylphorbol 13-acetate doses. A decrease in the paw swelling at the (TPA)-induced inflammation in mice in dose of 10 mg/kg BW has been reported. comparison to indomethacin, a commercially At the doses of 50 to 100 mg/kg BW, available anti-inflammatory [2]. the anti-inflammatory effect was similar to All oleanolic acid derivatives exhibited the standard indomethacin at the dose of marked anti-inflammatory activities with the

10 to 20 mg/kg [44]. 50% inhibitory doses (ID50) of 0.02-0.38 The saponin mixture of mmol/ear, which are more potent than the seeds was evaluated for anti-inflammatory reference indomethacin (ID50 0.91 mmol/ear) activity using acute (carrageenan-induced (Table 3). The anti-inflammatory activity inflammation), sub-acute (formaldehyde- of these compounds has been demonstrated induced inflammation), and chronic (cotton to be similar to that of the inhibition of pellet granuloma) models in rats [45]. dimethylbenz(a)anthracene (DMBA)-TPA The saponin mixture at the doses level papilloma formation in the mouse-skin of 1.5 and 3 mg/kg BW significantly model [47]. Hence, the oleanolic acid reduced the edema induced by carrageenan derivatives might be expected to possess in the acute model, inhibiting both phases high antitumor-promoting effect in the of inflammation. The saponin mixture gave same animal model. a more effective response than the reference drug, diclofenac sodium (NSAID) in the 12. CYTOTOXIC ACTIVITY sub-acute inflammation model. Results The antiproliferative effect of saponin indicated a significant anti-inflammatory fraction extracted from the argan press activity by Madhuca longifolia saponins in the cakes has been evaluated on three human cotton pellet granuloma model. Thus, these prostatic cancer cell lines (DU145, LNCaP, saponins can be developed further for and PC3) [48-49]. The saponin fraction long term symptomatic treatment involving displayed the best antiproliferative effect inflammation. Commercial therapeutic uses of on the PC3 cell line with the GI50 M. longifolia seed saponins would be value (the concentration for 50% of economical since its seeds are rich in saponin maximal inhibition of cell proliferation) content and can be obtained as a by-product of 18 μg/ml. 2546 Chiang Mai J. Sci. 2018; 45(7) c) 50 330 353 360 368 410 335 479 348 455 456 470 460 339 371 380 397 of EBV-EA induction, IC Inhibitory effects b) Ratio 0.31 0.70 0.74 0.70 0.67 0.59 0.36 0.56 1.05 0.73 1.25 0.48 0.35 0.57 0.46 0.88 C / with 32 pmol TPA. A reference wavelength) nm, respectively, by nm, respectively, reference wavelength) Cell 69.6 90.0 37.3 85.0 74.8 67.8 67.6 45.6 29.4 88.2 90.5 82.1 101.1 109.0 113.8 112.1 viability (%) 21.6 70.7 81.0 79.6 75.2 52.8 13.4 47.7 78.9 49.7 84.8 22.1 10.4 50.2 42.0 72.2 Melanin Melanogenesis-inhibitory activity content (%) a) 72.7 31.4 30.1 29.7 32.0 18.8 >100 >100 >100 >100 >100 >100 >100 >100 >100 >100 M) SK-BR-3 μ ( 50 9.5 98.2 10.9 17.9 77.8 86.4 >100 >100 >100 >100 >100 >100 >100 >100 >100 >100 AZ521 13.5 19.1 48.5 18.4 A549 >100 >100 >100 >100 >100 >100 >100 >100 >100 >100 >100 >100 Cytotoxicity, IC Cytotoxicity, M) for 48 h, and cell viability was analyzed by the MTT assay. analyzed by was M) for 48 h, and cell viability -6 7.6 4.2 80.7 23.0 15.4 19.4 82.0 >100 >100 >100 >100 >100 >100 >100 >100 >100 10 HL-60 × 50 to 1 -4 10 × 0.02 0.13 0.16 0.07 0.13 0.19 0.18 0.17 0.18 0.12 0.38 0.05 0.91 (mmol/ear) Inhibition of inflammation, ID . Inhibition of and inhibitory effects of melanogenesis-inhibitory activity, inflammation activities, cytotoxic in mice, EBV-EA values represent the molar ratios of the compounds, relative to TPA, required to inhibit 50% of represent ofvalues the molar ratios activated to control TPA, relative the positive the compounds, 50 Cells were treated with the compounds (1 treated Cells were -

a) comparison with those for DMSO (100%). c) IC b) Melanin content and cell viability were determined at 100 mM based on the absorbances at 405 and 570 (test wavelength) 630 ( determined atb) Melanin content and cell viability were 405 and 570 (test wavelength) at 100 mM based on the absorbances Compound 1 5 16 18 19 29 31 36 37 38 39 40 69 70 71 Reference compounds Indomethacin Cisplatin Arbutin β induction of saponins isolated from the defatted shea kernel extract. Table 3 Table Chiang Mai J. Sci. 2018; 45(7) 2547

An ethanolic root extract of Sideroxylon respectively. It also showed a moderate foetidissimum revealed cytotoxic activity activity against MDA-MB 231 and HCT116 against murine macrophage-like cell line cell lines (the IC50 values of 9.62 and 14.12 RAW 264.7. The original fraction containing μM, respectively). With respect to compound saponins 13, 33, 34, 46, 47, and 50, purified 76, compound 75 was less active of about samples of 13, 34, and 47, and the 5:4 mixture nine-fold against T98G and A375 cell lines of 33 and 50 have been tested for cytotoxicity and about four-fold against MDA-MB against the murine macrophage-like cell 231 and HCT116 cell lines. The higher line RAW 264.7 [34]. The 5:4 mixture of 33 cytotoxicity observed for compound 76 and 50 showed greater cytotoxicity (IC50 compared to compound 75 could be 11.9 μg/ml) on RAW 264.7 cells than the correlated with the presence of the apiose μ original extract (IC50 39.5 g/ml), and its units, as already suggested for the derived saponin-containing fraction (IC50 triterpenoid saponins isolated from the aerial 33.7 μg/ml). But, saponins 13, 34, and 47 were parts of Conyza blini [53] and the pectic not active. Thus, the aglycone moiety (16α- obtained from the cell wall hydroxyprotobassic acid) of 33, 34, 46, 47, of the marine phanerogam Zostera marina and 50 is not a structural determinant [54]. The inactivity of compound 41 in this of cytotoxicity. Although various types of assay could be attributed to its aglycone biological activity have been associated (16α-hydroxyprotobassic acid), which has with the sugar moieties of saponins [50], been established to be not a structural bisdesmosides are often inactive, and determinant of cytotoxicity [34]. are thought to serve primarily as transport The cytotoxic activities of two and/or storage forms of monodesmosides sapogenols, 1 and 69, and thirteen saponins, [51]. Thus, the cytotoxic activity of the 5:4 5, 16, 18, 19, 29, 31, 36-40, 70, and 71, mixture of 33 and 50, which comprised of isolated from the methanolic extract of the two bisdesmosidic saponins, is noteworthy. defatted shea kernels, were evaluated along It has been reported that sideroxyloside with the reference chemotherapeutic drug, A (9), isolated from the roots of Sideroxylon cisplatin, against the human cancer cell cubense, showed strong cytotoxic activity on lines HL-60 (leukemia), A549 (lung), AZ521 both Molt 4 cells and splenocytes [52]. (duodenum), and SK-BR-3 (breast) by the The antiproliferative activity of parkioside MTT (thiazolyl blue tetrazolium bromide) C (41), parkioside A (75), and parkioside B assay [2]. While nine compounds, 1, 29, 31, (76), isolated from the n-butanolic extract 36, 39, 40, 69, 70, and 71, exhibited potent of the root bark of Vitellaria paradoxa or moderate cytotoxicities against one or

(Butyrospermum parkii), was evaluated against more cell lines with the IC50 values in the human breast adenocarcinoma (MDA-MB- range of 7.6-98.2 μM, other six compounds

231), malignant melanoma (A375), colon were inactive against all cell lines (IC50 > 100 carcinoma (HCT116) and glioblastoma μM) (Table 3). In particular, the cytotoxic multiforme (T98G) cell lines [37]. Compound activities of 39 and 40 against A549 cell μ 41 was not active while compounds 75 and line (IC50 13.5 and 19.1 M, respectively) μ 76 showed in vitro cytotoxic activity against and 71 against HL-60 cell line (IC50 7.6 M) all cell lines. Compound 76 was the most were more potent than, or almost comparable μ active, with the IC50 values of 2.74 and with the reference cisplatin [IC50 18.4 M 2.93 μM against A375 and T98G cell lines, (A549), 4.2 μM (HL-60)]. With respect to the 2548 Chiang Mai J. Sci. 2018; 45(7)

oleanolic acid derivatives, highly glycosylated antioxidant effect of vitamin E. bisdesmosides (i.e., 31, 39, 40), exhibited, in In an in vitro luminol-enhanced general, more potent cytotoxic activities than chemiluminescence assay, madhucosides A those with less glycosylated, i.e., 5, 16, 18, 19, (24) and B (27), isolated from the bark of 29, 36, 37, 38, 71, and 70. The cytotoxic Madhuca indica, inhibited the production of activity of 39, which exhibited potent hypochlorous acid by human neutrophils μ cytotoxic activity against A549 cells (IC50 13.5 with the IC50 of 21.9 and 144 g/ml, μ M), has been demonstrated mainly due to respectively, compared with the IC50 of an induction of apoptosis by flow cytometry 19.84 μg/ml of bacoside A3, a reference [2]. standard [19]. Further, in the NBT (nitroblue tetrazolium) reduction assay used for the 13. ANTIOXIDATIVE ACTIVITY quantification of superoxide production Oxidative damage to cellular membranes from polymorphonuclear cells, 24 was found may contribute to the initiation and to have an inhibitory effect with the IC50 μ progression of several degenerative of 138.3 g/ml, as compared to the IC50 diseases. The hydroxy free radical (⋅OH), values of 111.0 and 14.1 μg/ml of the two quite abundant under physiological reference standards, and ascorbic conditions, reacts readily with practically acid, respectively. However, only 16% any type of biological molecules in living cells, inhibition was achieved in the case of 27 at such as sugars, amino acids, , the highest concentration of 200 μg/ml. and DNA bases. Therefore, scavenging of The radical scavenging activity of three ⋅OH is considered an important reaction compounds, 41, 75, and 76, isolated from the underlying many health benefits of food n-butanolic extract of the root bark of antioxidants. Vitellaria paradoxa, was screened against Argania spinosa saponins have an 2,2-diphenyl-1-picrylhydrazyl (DPPH), antiradical action against DPPH (IC25 85 mM) 2,22-azino-bis(3-ethylbenzothiazoline-6- ⋅ and against OH radicals (IC25 0.56 M) [44]. sulfonic acid) (ABTS), nitric oxide (NO), Since they do not have any inhibition effect and oxygen radicals [37]. Compound 76 on PGE2 synthesis, their anti-inflammatory showed a dose dependent DPPH (IC50 μ μ activity can be explained by their action on 16.2 M) and ABTS (IC50 25 M) radial leukotrienes in the metabolic pathway of scavenging comparable with Trolox μ μ arachidonic acid. [IC50: 18.8 M (DPPH), 12.5 M (ABTS)]. Saponins from argan press-cake at a The terminal apiofuranosyl moiety of the non-haemolytic concentration diminish by sugar chain at C-28 (u) of compound 76 53.2% erythrocyte haemolysis induced by may be responsible for enhancing its free radicals [55]. A combination of 1 mg/l radical scavenging activities. of A. spinosa saponins and vitamin E at 0.3 μM resulted in a 68% level of protection 14. MELANOGENESIS-INHIBITORY ACTIVITY against free radical-induced erythrocyte Two sapogenols, 1 and 69, and thirteen haemolysis, which may suggest that A. spinosa saponins, 5, 16, 18, 19, 29, 31, 36, 37, 38, 39, saponins enhance the antioxidant effect of 40, 70, and 71, isolated from the methanolic vitamin E. These results demonstrate the extract of the defatted shea (Vitellaria paradoxa) antioxidant properties of saponins from kernels, were evaluated for melanogenesis A. spinosa and their ability to potentate the inhibition in α-MSH (melanocyte-stimulating Chiang Mai J. Sci. 2018; 45(7) 2549

hormone)-stimulated B16 4A5 (mouse of melanogenesis-inhibitory activities of melanoma) cells [2]. The cytotoxic activities all samples in B16 melanoma cells induced of these compounds against B16 melanoma by α-MSH, samples S2 (; triterpenoid cells were also determined by the MTT assay. saponin content: 6.0%), S3 (; 5.0%), To assess the risk/benefit ratio of each and S21 (; 8.0%) were lower-risk compound, the relative activities vs. toxicities melanogenesis inhibitors (39.4-42.5% were calculated by dividing the melanin melanin content, 78.6-91.6% cell viability) content (%), by the cell viability (%), with low A/C ratio (0.18-0.94), and gave and expressed as activity-to-cytotoxicity superior activity to the reference arbutin ratio (A/C ratio) for each compound. at the concentration of 100 μg/ml. These A compound with a lower A/C ratio would results suggest that the extracts of the be a lower-risk skin-whitening agent [2]. defatted shea kernels and their constituents Eight oleanolic acid derivatives, 5, 16, 18, can be regarded as skin whitening agents. 19, 29, 36, 70, and 71, exhibited lower-risk melanogenesis inhibition (42.0-81.0% 15. INHIBITORY EFFECTS ON EBV-EA melanin content, and 85.0-113.8% cell INDUCTION (POTENTIAL CANCER viability) with low A/C ratios (0.46-0.74) at CHEMOPREVENTIVE EFFECTS) the concentration of 100 μM (Table 3). The inhibitory effects against Epstein- The inhibitory activities on melanogenesis Barr virus early antigen (EBV-EA) activation of these compounds were almost comparable induced by TPA in Raji cells, of the two with, or superior to, the reference sapogenols, 1 and 69, and thirteen saponins, melanogenesis inhibitor, arbutin (4- 5, 16, 18, 19, 29, 31, 36-40, 70, and 71, hydroxyphenyl β-D-glucopyranoside; isolated from the methanolic extract of 72.2 % of melanin content and 0.88 of the defatted shea kernels, against TPA A/C ratio at 100 μM), which is widely (32 pmol)-induced EBV-EA activation in used in cosmetic formulations designed Raji cells, together with the comparable to lighten or brighten skin color [56]. data of β-carotene, a vitamin A precursor As far as the oleanolic acid derivatives widely studied in cancer chemoprevention are concerned, the monodesmosides animal models, are compiled in Table 3 [2]. glycosylated at C-3, i.e., compounds 5, 16, 18, All compounds showed inhibitory effects

19, 29, 36, 70, and 71, showed more potent with the IC50 values (concentration for 50% melanogenesis than the bisdesmosides inhibition with respect to the positive glycosylated at C-3 and C-28, i.e., compounds control) of 330-479 molar ratio/32 pmol 31 and 37-40. Western blot analysis has TPA. Among these, nine oleanolic acid indicated that paradoxoside E (71) inhibited derivatives, 1, 5, 16, 18, 29, 36, 69, 70, and 71, melanogenesis by regulation of expression exhibited potent inhibitory effects (330-380 of microphthalmia-associated transcription molar ratio/32 pmol TPA) higher than factor (MITF), tyrosinase, and tyrosinase- that of β-carotene (397 molar ratio/32 pmol related protein-1 (TRP-1) and TRP-2. TPA). The bisdesmosides glycosylated at

Twenty-six methanolic extracts of the C-3 and C-28, i.e., 31, 37, 38, 39, and 40 (IC50 defatted shea kernels from seven sub-Saharan 455-479 molar ratio/32 pmol TPA), followed countries, i.e., Cote d’Ivoire, Ghana, Nigeria, by the monodesmoside gycosylated at C-3

Cameroon, Chad, , and Uganda, have with a diglycosyl unit, i.e., 19 (IC50 410 molar been investigated [4]. From the evaluation ratio/32 pmol TPA), of oleanolic acid 2550 Chiang Mai J. Sci. 2018; 45(7)

derivatives exhibited lower inhibitory further study as an antiviral drug. effects of EBV induction. On the other hand, the monodesmosides glycosylated at C-3 17. ANTIFUNGAL ACTIVITY with a monoglycosyl unit, i.e., 5, 16, 18, 29, 36, The antifungal activity of a crude

70, and 71 (IC50 335-380 molar ratio/32 pmol mixture of argan seed kernel saponins TPA), and those of sapogenols, i.e., 1 and 69 was evaluated and the minimal inhibitory

(IC50 330 and 339 molar ratio/32 pmol TPA, concentration was obtained at 12.5 and respectively), exhibited higher inhibitory 50 μg/ml against Cladosporium cucumerinum effects of EBV induction. Since the inhibitory and Polysticus versicolor, respectively [11]. effects against EBV-EA induction have been demonstrated to correlate with those against 18. ACUTE AND CHRONIC TOXICITY tumor promotion in vivo [1, 57], compounds Acute and chronic toxicities of 1, 5, 16, 18, 29, 36, 69, 70, and 71, may be saponins of argan press-cake have potential inhibitors of tumor promotion. been determined following oral and intraperitoneal administration in mice 16. ANTIVIRAL ACTIVITY and rats. Concerning the acute toxicity

Mimusopic acid (77), isolated from the for oral route, the LD50 was 1.3 g/kg. seeds of Mimusops elengi [32], showed mild Concerning the chronic toxicity, at the doses anti-HIV reverse transcriptase (RT) inhibitory of 100 and 200 mg/kg BW, a decrease in activity compared with epigallocatechin blood sugar level was reported after the gallate (EGCG), a green tea component third month together with a possible renal and an efficient inhibitor of HIV-RT. pathology [58]. At the concentrations of 2, 5 and 10 μg/ml, the RT activity was found to be 82.6, 67.9 19. CONCLUSIONS and 9.6%, respectively, compared with 71.0, Most of the triterpenoid saponins found 9.5 and 1.1% activity in the presence of 0.04, in the Sapotaceae plants are bisdesmosides 0.1 and 0.2 μg/ml of EGCG [29]. with sugar chains at the C-3 and C-28 Arganine C (31) and tieghemelin (39) positions, and contain protobassic acid (I) were isolated from Tieghemella heckelii or 16α-hydroxyprotobassic acid (II) as fruits. Arganine C (31) strongly inhibited aglycone which may be considered as a HIV entry (100% inhibition at 20 μM) chemical marker of these species. In addition, into cells in a cell fusion assay [36]. The less the one-sugar core, Glc (B), at C-3, and the potent 39 was converted into 31 by four-sugar core, Ara-Rha-Xyl-Rha (i), at reduction of its ethyl ester with NaBH4. C-28, are detected most frequently in the The removal of four-sugar chains from 31 Sapotaceae saponins, and the saponin and 39 to give 16α-hydroxyprotobassic sequence Glc-aglycone-Ara-Rha-Xyl-Rha acid 3-O-β-D-glucopyranoside (29) and might represent a chemotaxonomic marker 16α- hydroxyprotobassic acid 3-O-β-D- of the family Sapotaceae. This is consistent glucuronopyranoside (36), respectively, with the occurrence of arganine C (31; caused the total loss of activity in both cases. Glc-II-Ara-Rha-Xyl-Rha) as the most Saponin 31 was not significantly cytotoxic common saponin of the Sapotaceae plants. to HeLa-CD4+ cells at the level required These Sapotaceae triterpenoid saponins to reduce the syncytium count to zero, (including sapogenols) exhibited a variety of suggesting it as a promising candidate for biological activities such as anti-inflammatory, Chiang Mai J. Sci. 2018; 45(7) 2551

cytotoxic, antioxidative, melanogenesis- maximal inhibition of cell proliferation. inhibitory, anti-tumor promoting, antiviral, and Glc = β-D-Glucopyranosyl antifungal activities. Especially, protobassic GlcA = β-D-Glucuronopyranosyl acid (1), paradoxoside C (18), and 3-O-β-D- HIV-RT = HIV reverse transcriptase glucopyranosyl bassic acid (70); tiehemelin HPLC = High-performance liquid (39), butyroside D (40), paradoxoside E chromatography β (71), and parkioside B (76); 76; 3-O- -D- IC50 = Median inhibitory concentration α glucopyranosyl 16 -hydroxyprotobassic ID50 = Median infective dose β α acid (29), 3-O- -D-glucuronopyranosyl 16 - LD50 = Median lethal dose protobassic acid (36), 70, and paradoxoside MeGlcA = 6-O-Methyl E (71); and 1, 29, 36, and bassic acid (69), β-D-glucuronopyranosyl isolated all from V. paradoxa, have been MeOH = Methanol proved to exhibit potent anti-inflammatory, MITF = Microphthalmia-associated cytotoxic, antioxidative, melanogenesis- transcription factor inhibitory, and EBV-EA induction inhibitory MTT = 3-(4,5-Dimethylthiazol-2-yl)-2, activities, respectively (cf., Table 3). Moreover, 5-diphenyltetrazolium bromide saponin 31 has been demonstrated to exhibit MS = Mass spectrometry potent antiviral activity. These compounds, NBT = Nitroblue tetrazolium therefore, warrant more attention for NO = Nitric oxide possible development as anti-inflammatory NMR = Nuclear magnetic resonance agents, anticancer agents, antioxidants, skin- NSAID = Non-steroidal anti-inflammatory whitening agents, cancer chemopreventive drug agents, and as antiviral agents. In addition, Rha = α-L-Rhamnopyranosyl since a many Sapotaceae plants including TPA = 12-O-Teradecanoylphorbol 13-acetate those described in this article have long TRP-1 = Tyrosinase-related protein-1 been utilized as traditional medicines and Xyl = β-D-Xylopyranosyl cosmetics, it might be worthwhile to undertake more extensive and systematic investigations REFERENCES on their saponins and other bioactive [1] Akihisa T., Zhang J. and Tokuda H., constituents in the future. Studies in Natural Products Chemistry, 2016; 51: 1-50. LIST OF ABBREVIATION [2] Zhang J., Kurita M., Shinozaki T., ABTS = 2,2′-Aazino-bis Ukiya M., Yasukawa K., Shimizu N., (3-ethylbenzothiazoline-6-sulfonic acid) Tokuda H., Masters E.T., Akihisa M. A/C ratio = Activity-to-cytotoxicity ratio and Akihisa T., Phytochemistry, 2014; 108: α -MSH = Melanocyte-stimulating hormone 157-170. Api = β-D-Apiofuranosyl [3] Zhang J., Kurita M., Ebina K., Ukiya M., Ara = α-L-Arabinopyranosyl Tokuda H., Yasukawa K., Masters E.T., BW = Body weight Shimizu N., Akihisa M., Feng F. and DMBA = Dimethylbenz(a)anthracene Akihisa T., Chem. Biodivers., 2015; 12: DPPH = 2,2-Diphenyl-1-picrylhydrazyl 547-558. EBV-EA = Epstein-Barr virus early antigen ECGG = Epigallocathechin gallate [4] Zhang J., Lia D., Lv Q., Ye F., Jing X., Masters E.T., Shimizu N., Abe M., GI50 = The concentration for 50% of 2552 Chiang Mai J. Sci. 2018; 45(7)

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