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Myricetin: a Dietary Molecule with Diverse Biological Activities

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nutrients Review Myricetin: A Dietary Molecule with Diverse Biological Activities Deepak Kumar Semwal 1, Ruchi Badoni Semwal 1, Sandra Combrinck 1,2 and Alvaro Viljoen 1,2,* 1 Department of Pharmaceutical Sciences, Tshwane University of Technology, Pretoria 0001, South Africa; [email protected] (D.K.S.); [email protected] (R.B.S.); [email protected] (S.C.) 2 SAMRC Herbal Drugs Research Unit, Faculty of Science, Tshwane University of Technology, Pretoria 0001, South Africa * Correspondence: [email protected]; Tel.: +27-12-382-6360; Fax: +27-12-382-6243 Received: 9 November 2015; Accepted: 23 December 2015; Published: 16 February 2016 Abstract: Myricetin is a common plant-derived flavonoid and is well recognised for its nutraceuticals value. It is one of the key ingredients of various foods and beverages. The compound exhibits a wide range of activities that include strong anti-oxidant, anticancer, antidiabetic and anti-inflammatory activities. It displays several activities that are related to the central nervous system and numerous studies have suggested that the compound may be beneficial to protect against diseases such as Parkinson’s and Alzheimer’s. The use of myricetin as a preserving agent to extend the shelf life of foods containing oils and fats is attributed to the compound’s ability to protect lipids against oxidation. A detailed search of existing literature revealed that there is currently no comprehensive review available on this important molecule. Hence, the present work includes the history, synthesis, pharmaceutical applications and toxicity studies of myricetin. This report also highlights structure-activity relationships and mechanisms of action for various biological activities. Keywords: myricetin; anti-oxidant activity; anti-HIV activity; cytotoxicity; polyphenol; anti-alzheimer activity 1. Introduction Although myricetin occurs throughout the Plant Kingdom, it is produced mainly by members of the families Myricaceae [1,2], Anacardiaceae [3], Polygonaceae [4], Pinaceae [5] and Primulaceae [6]. This phenolic compound is very common in berries, vegetables, and in teas and wines produced from various plants. It occurs in both the free and glycosidically-bound forms, which include myricetin-3-O-(3”-acetyl)-α-L-arabinopyranoside, myricetin-3-O-(4”-acetyl)-α-L-arabinopyranoside, myricetin-3-O-α-L-rhamnopyranoside, myricetin-3-O-β-D-galactopyranoside, myricetin-3-O- (6”-galloyl) -β-D-galactopyranoside, myricetin-3-O-β-D-xylopyranoside, myricetin 3-O-α-L- arabinofuranoside [7], myricetin-3-O-(2”-O-galloyl)-α-L-rhamnoside, myricetin-3-O-(3”-O-galloyl)- α-L-rhamnoside and myricetin-3-O-α-L-rhamnoside [8]. Myricetin is poorly soluble in water, i.e., 16.6 µg/mL, but dissolves rapidly when deprotonated in basic aqueous media and in some organic solvents such as dimethylformamide, dimethylacetamide, tetrahydrofuran and acetone [9]. Moreover, degradation of this compound, which is most stable at pH 2, was reported to be both pH and temperature dependent. The history of myricetin (1) extends back to more than a hundred years. It was first isolated in the late eighteenth century from the bark of Myrica nagi Thunb. (Myricaceae), harvested in India, as light yellow-coloured crystals [10]. Isolation was primarily sparked by interest in the dyeing property of the compound. It was well characterised in a further study of Perkin [11], who established the melting point as 357 ˝C and prepared various bromo, methyl, ethyl and potassium analogues. This report also described myricitrin (2), a myricetin glycoside (myricetin-3-O-rhamnoside), for the first time. Nutrients 2016, 8, 90; doi:10.3390/nu8020090 www.mdpi.com/journal/nutrients Nutrients 2016, 8, 90 2 of 31 The history of myricetin (1) extends back to more than a hundred years. It was first isolated in the late eighteenth century from the bark of Myrica nagi Thunb. (Myricaceae), harvested in India, as light yellow-coloured crystals [10]. Isolation was primarily sparked by interest in the dyeing property of the compound. It was well characterised in a further study of Perkin [11], who Nutrientsestablished2016, 8the, 90 melting point as 357 °C and prepared various bromo, methyl, ethyl and potassium2 of 31 analogues. This report also described myricitrin (2), a myricetin glycoside (myricetin-3-O-rhamnoside), for the first time. In a subsequent study, Perkin [12] found that myricetin yields a phloroglucinol and In a subsequent study, Perkin [12] found that myricetin yields a phloroglucinol and gallic acid upon gallic acid upon hydrolysis, which served to confirm its chemical structure. hydrolysis, which served to confirm its chemical structure. Myricetin (1) is structurally related to several well-known phenolic compounds (Figure 1), Myricetin (1) is structurally related to several well-known phenolic compounds (Figure1), namely namely quercetin (3), morin (4), kaempferol (5) and fisetin (6). The compound is sometimes referred quercetin (3), morin (4), kaempferol (5) and fisetin (6). The compound is sometimes referred to as to as hydroxyquercetin, resulting from its structural similarity to quercetin (3). The nutraceuticals hydroxyquercetin, resulting from its structural similarity to quercetin (3). The nutraceuticals and and anti-oxidant properties of myricetin are highly valued. Scientific evidence [13] underscores anti-oxidant properties of myricetin are highly valued. Scientific evidence [13] underscores claims that claims that the compound displays a variety of pharmacological activities, including the compound displays a variety of pharmacological activities, including anti-inflammatory, analgesic, anti-inflammatory, analgesic, antitumour, hepatoprotective and antidiabetic activities. antitumour, hepatoprotective and antidiabetic activities. R4 R 3' R 3 2' 5 4' 1' B HO 8 O 5' R 7 2 6' 6 A C 3 6 5 4 R1 R2 O Myricetin (1) [R1=R2=R4=R5=R6=OH; R3=H] Myricitrin (2) [R1=Rham; R2=R4=R5=R6=OH; R3=H] Quercetin (3) [R1=R2=R4=R5=OH; R3=R6=H] Morin (4) [R1=R2=R3=R5=OH; R4=R6=H] Kaempferol (5) [R1=R2=R5=OH; R3=R4=R6=H] Fisetin (6) [R1=R5=R6=OH; R2=R3=R4=H] FigureFigure 1.1. ChemicalChemical structuresstructures ofof myricetinmyricetin andand relatedrelated compounds.compounds. 2.2. Chemical Chemical Synthesis Synthesis TheThe synthesissynthesis ofof myricetinmyricetin isis veryvery importantimportant inin termsterms ofof itsits useuse asas aa keykey startingstarting materialmaterial forfor thethe synthesissynthesis ofof variousvarious otherother beneficialbeneficial compounds compounds including including hibiscetin hibiscetin [ 14[14,15,15].]. Dean Dean and and Nierenstein Nierenstein [ 16[16]] firstfirst attemptedattempted toto synthesisesynthesise myricetinmyricetin inin 19251925 byby applyingapplying thethe KostaneckiKostanecki andand AuwersAuwers procedureprocedure whichwhich waswas unfortunately,unfortunately, notnot successful.successful. In the same year, KalffKalff andand RobinsonRobinson [[17]17] managedmanaged toto synthesisesynthesise myricetinmyricetin fromfrom !ω-methoxyphloroacetophenone.-methoxyphloroacetophenone. ThisThis methodmethod involvedinvolved heatingheating thethe startingstarting materialmaterial togethertogether withwith trimethylgallictrimethylgallic anhydrideanhydride andand sodiumsodium trimethylgallate.trimethylgallate. FollowingFollowing hydrolysishydrolysis ofof thethe product,product, 5,7-dihydroxy-3,35,7-dihydroxy-3,31′,4,41′,5,51′-tetramethoxyflavone-tetramethoxyflavone waswas formed,formed, whichwhich finallyfinally yieldedyielded myricetinmyricetin afterafter demethylationdemethylation (Scheme(Scheme1 1).). OnOn thethe otherother hand, hand, using using an an alternative alternative route, route, Rao Rao and and Seshadri Seshadri [ [18]18] synthesisedsynthesised myricetinmyricetin from quercetinquercetin viavia anan ortho-oxidationortho-oxidation reaction (Scheme 22).). InIn thisthis procedure,procedure, 3,5,7,33,5,7,31′--tetra-tetra-OO--methylquercetinmethylquercetin was was converted converted to the correspondingcorresponding 551′-aldehyde,-aldehyde, which waswas thenthen convertedconverted to 3,5,7,3 ′1--tetra-tetra-OO-methylmyricetin-methylmyricetin to to yield yield 5- 5-methoxykanugin,methoxykanugin, following following cyclisation cyclisation at the at the4′ and 41 and 5′ 5positions.1 positions. Hydrolysis Hydrolysis of of 5 5-methoxykanugin,-methoxykanugin, with with subsequent methylation,methylation, yieldedyielded hexamethylmyricetin,hexamethylmyricetin, which finally finally produced myricetin myricetin upon upon demethylation demethylation.. Nutrients 2016, 8, 90 3 of 31 Nutrients 2016, 8, 90 3 of 31 Nutrients 2016, 8, 90 3 of 31 OH O OCH3 H CO OCH OH O 3 3 - + OCH3 H CO OCH O Na OCH 3 O O 3 - + 3 Na O O O OCH3 OCH H CO 3 3 OCH3 OCH O 3 H3CO OCH3 HO OH O O O OCH3 HO OH H CO OCH Methoxyphloroacetophenone 3 Trimethylgallic anhydride 3 Sodium trimethylgallateOCH H CO 3 Methoxyphloroacetophenone 3 Trimethylgallic anhydride OCH3 Sodium trimethylgallate 1. Heat 2.1. HydrolysisHeat 2. Hydrolysis OH OCH3 OH OCH3 OH OCH3 OH OCH3 HO O HO O OH [Demethylation] OCH3 HO O HO O OH [Demethylation] OCH3 OH OCH3 OH O OH OH O OCH3 Myricetin 5,7-Dihydroxy-3,3',4',5'-tetramethoxyflavone OH O OH O MyricetinScheme 1. Synthesis of myricetin as proposed by5,7-Dihydroxy-3,3',4',5'-tetramethoxyflavone Kalff and Robinson [17]. Scheme 1. Synthesis of myricetin as proposed by Kalff and Robinson [17]. Scheme 1. Synthesis of myricetin as proposed by Kalff and Robinson [17]. OCH3 OCH3 OH OH OCH3 OCH3 OH OH H3CO O H3CO O CHO H3CO O H3CO O CHO OCH3 OCH3 OCH3 O OCH3 O
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    PHYTOCHEMICAL STUDIES OF ARTEMISIA ANNUA L. THESIS Presented by SHILIN YANG For the Degree of DOCTOR OF PHILOSOPHY of the UNIVERSITY OF LONDON DEPARTMENT OF PHARMACOGNOSY THE SCHOOL OF PHARMACY THE UNIVERSITY OF LONDON BRUNSWICK SQUARE, LONDON WC1N 1AX ProQuest Number: U063742 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a com plete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. uest ProQuest U063742 Published by ProQuest LLC(2017). Copyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States C ode Microform Edition © ProQuest LLC. ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106- 1346 ACKNOWLEDGEMENT I wish to express my sincere gratitude to Professor J.D. Phillipson and Dr. M.J.O’Neill for their supervision throughout the course of studies. I would especially like to thank Dr. M.F.Roberts for her great help. I like to thank Dr. K.C.S.C.Liu and B.C.Homeyer for their great help. My sincere thanks to Mrs.J.B.Hallsworth for her help. I am very grateful to the staff of the MS Spectroscopy Unit and NMR Unit of the School of Pharmacy, and the staff of the NMR Unit, King’s College, University of London, for running the MS and NMR spectra.
  • Texas Big Tree Registry a List of the Largest Trees in Texas Sponsored by Texas a & M Forest Service

    Texas Big Tree Registry a List of the Largest Trees in Texas Sponsored by Texas a & M Forest Service

    Texas Big Tree Registry A list of the largest trees in Texas Sponsored by Texas A & M Forest Service Native and Naturalized Species of Texas: 320 ( D indicates species naturalized to Texas) Common Name (also known as) Latin Name Remarks Cir. Threshold acacia, Berlandier (guajillo) Senegalia berlandieri Considered a shrub by B. Simpson 18'' or 1.5 ' acacia, blackbrush Vachellia rigidula Considered a shrub by Simpson 12'' or 1.0 ' acacia, Gregg (catclaw acacia, Gregg catclaw) Senegalia greggii var. greggii Was named A. greggii 55'' or 4.6 ' acacia, Roemer (roundflower catclaw) Senegalia roemeriana 18'' or 1.5 ' acacia, sweet (huisache) Vachellia farnesiana 100'' or 8.3 ' acacia, twisted (huisachillo) Vachellia bravoensis Was named 'A. tortuosa' 9'' or 0.8 ' acacia, Wright (Wright catclaw) Senegalia greggii var. wrightii Was named 'A. wrightii' 70'' or 5.8 ' D ailanthus (tree-of-heaven) Ailanthus altissima 120'' or 10.0 ' alder, hazel Alnus serrulata 18'' or 1.5 ' allthorn (crown-of-thorns) Koeberlinia spinosa Considered a shrub by Simpson 18'' or 1.5 ' anacahuita (anacahuite, Mexican olive) Cordia boissieri 60'' or 5.0 ' anacua (anaqua, knockaway) Ehretia anacua 120'' or 10.0 ' ash, Carolina Fraxinus caroliniana 90'' or 7.5 ' ash, Chihuahuan Fraxinus papillosa 12'' or 1.0 ' ash, fragrant Fraxinus cuspidata 18'' or 1.5 ' ash, green Fraxinus pennsylvanica 120'' or 10.0 ' ash, Gregg (littleleaf ash) Fraxinus greggii 12'' or 1.0 ' ash, Mexican (Berlandier ash) Fraxinus berlandieriana Was named 'F. berlandierana' 120'' or 10.0 ' ash, Texas Fraxinus texensis 60'' or 5.0 ' ash, velvet (Arizona ash) Fraxinus velutina 120'' or 10.0 ' ash, white Fraxinus americana 100'' or 8.3 ' aspen, quaking Populus tremuloides 25'' or 2.1 ' baccharis, eastern (groundseltree) Baccharis halimifolia Considered a shrub by Simpson 12'' or 1.0 ' baldcypress (bald cypress) Taxodium distichum Was named 'T.