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Liquid chromatography/ultraviolet (LC/UV) and mass spectrometry/mass spectrometry (MS/MS) libraries containing 39 phenolic compounds were established by coupling a LC and an ion trap MS with an electrospray ionization (ESI) source, operated in negative io

The phytochemical resveratrol (trans-3,5,4′-trihydroxystilbene) has drawn great interest as health-promoting food ingredient and potential therapeutic agent. However, resveratrol shows vanishingly low water solubility; this limits its uptake and complicates the development of effective therapeutic forms. Glycosylation should be useful to enhance resveratrol solubility, with the caveat that unselective attachment of sugars could destroy the molecule's antioxidant activity. UGT71A15 (a uridine 5′-diphosphate α-D-glucose-dependent glucosyltransferase from apple) was used to synthesize resveratrol 3,5-β-D-diglucoside; this was about 1700-fold more water-soluble than the unglucosylated molecule (～0.18 mM), yet retained most of the antioxidant activity. Resveratrol 3-β-D-glucoside, which is the naturally abundant form of resveratrol, was a practical substrate for perfect site-selective conversion into the target diglucoside in quantitative yield (gL-1 concentration).

Microbial transformation of resveratrol (1), trans-3,4',5- trihydroxystilbene, was studied. Preparative scale biotransformation of 1 with whole-cell suspensions of Bacillus cereus UI 1477 resulted in the production of metabolite 2 which was identical in a

Starting from the commercially available natural product (E)-resveratrol (1), the four selectively tert-butyldimethylsilyl (TBS) protected (E)-resveratrols 6-9 were prepared by one reaction. Using 6-9 as glucosyl acceptors and trifluoroacetimidate 11 as glucosyl donor, three bioactive natural glucopyranoside conjugates of (E)-resveratrol 2-4 and one novel compound (5) were efficiently prepared in two steps. Georg Thieme Verlag Stuttgart.

Nowadays, hop is used almost exclusively by brewers for bitterness and flavor. Although hop polyphenols have been widely studied in the past decade for their antioxidant activity in the boiling kettle, very little is known about their real impact on healt

Because of the health implications of resveratrol and piceid, which are widely present in foods, we focused our attention on the development of a highly efficient methodology for their characterization and measurement. On the basis of our experience in capillary electrophoresis for separation of polyphenolic compounds, we developed a general analytical method for piceid identification which was also applicable to complex natural mixtures such as red wine. In view of its very limited availability from natural sources, we first directed our attention to the development of a synthetic route suitable to produce an adequate amount of polydatin (piceid or resveratrol 3-O-β-D-glucopyranoside). The latter was synthesized by a new one-step procedure which afforded the expected product in a good yield. The studied compounds were also investigated for their stability to UV irradiation.

Stilbenes are phenolic molecules that have antifungal effects in the plant and antioxidant and anti-cancer effects when consumed in the human diet. Glycosylation of stilbenes increases their solubility and may make them more easily absorbed by the intesti

(Chemical Equation Presented) A novel whole-cell screen for the identification of new glucosyltransferase (GT) biocatalysts within a recombinant enzyme library was developed. Following biotransformation, levels of D-glucose were used as a measure of biocatalysis. Twenty five enzymes that transfer D-glucose to trans-resveratrol were identified that have the regioselectivity shown in the picture.

Resveratrol exhibits various pharmacological activities, which are dependent upon phenolic hydroxyl groups. In this work, glucosamine, lipoic acid, or adamantanamine moiety was applied for attaching to ortho-position of hydroxyl group in resorcinol moiety of resveratrol (known as position-2). Antioxidant effects of the obtained hybrids were characterized using DNA oxidative systems mediated by ?OH, Cu2+/glutathione (GSH), and 2,2′-azobis(2-amidinopropanehydrochloride) (AAPH), respectively. The glucosyl-appended imine and amine at position-2 of resveratrol were found to show higher inhibitory effects than other resveratrol derivatives against AAPH-induced DNA oxidation. The antioxidative effect was quantitatively expressed by stoichiometric factor (n, the number of radical-propagation terminated by one molecule of antioxidant). The stoichiometric factors of glucosyl-appended imine and amine of resveratrol increased to 4.74 (for imine) and 4.97 (for amine), respectively, higher than that of resveratrol (3.70) and glucoside of resveratrol (3.49). It was thereby concluded that the combination of resveratrol with glucosamine at position-2 represented a novel pathway for modifying resveratrol structure in the protection of DNA against peroxyl radical-mediated oxidation.

Glycosylation of resveratrol was carried out by using the amylosucrase of Deinococcus geothermalis, and the glycosylated products were tested for their solubility, chemical stability, and biological activities. We synthesized and identified these two major glycosylated products as resveratrol-4'-O- α-glucoside and resveratrol-3-O-α-glucoside by nuclear magnetic resonance analysis with a ratio of 5:1. The water solubilities of the two resveratrol-α-glucoside isomers (α-piceid isomers) were approximately 3.6 and 13.5 times higher than that of β-piceid and resveratrol, respectively, and they were also highly stable in buffered solutions. The antioxidant activity of the α-piceid isomers, examined by radical scavenging capability, showed it to be initially lower than that of resveratrol, but as time passed, the α-piceid isomers' activity reached a level similar to that of resveratrol. The α- piceid isomers also showed better inhibitory activity against tyrosinase and melanin synthesis in B16F10 melanoma cells than β-piceid. The cellular uptake of the α-piceid isomers, which was assessed by ultra-performance liquid chromatography (UPLC) analysis of the cell-free extracts of B16F10 melanoma cells, demonstrated that the glycosylated form of resveratrol was gradually converted to resveratrol inside the cells. These results indicate that the enzymatic glycosylation of resveratrol could be a useful method for enhancing the bioavailability of resveratrol.

The 62nd residue of glycosyltransferase UGTBL1 was identified as a "hotspot" for glycosylation at 3-OH of resveratrol. Via semi-rational design including structure-guided alanine scanning and saturation mutations, the mutation I62G significantl

Grapevine stilbenes are a family of polyphenols which derive from trans-resveratrol having antifungal and antimicrobial properties, thus being considered as phytoalexins. In addition to their diverse bioactive properties in animal models, they highlight a strong potential in human health maintenance and promotion. Due to this relevance, highly-specific qualitative and quantitative methods of analysis are necessary to accurately analyze stilbenes in different matrices derived from grapevine. Here, we developed a rapid, sensitive, and specific analysis method using ultra-high-performance liquid chromatography coupled to triple-quadrupole mass spectrometry (UHPLC-QqQ) in MRM mode to detect and quantify five grapevine stilbenes, trans-resveratrol, trans-piceid, trans-piceatannol, trans-pterostilbene, and trans-?-viniferin, whose interest in relation to human health is continuously growing. The method was optimized to minimize in-source fragmentation of piceid and to avoid co-elution of cis-piceid and trans-resveratrol, as both are detected with resveratrol transitions. The applicability of the developed method of stilbene analysis was tested successfully in different complex matrices including cellular extracts of Vitis vinifera cell cultures, reaction media of biotransformation assays, and red wine.

The stilbene compound resveratrol was glycosylated to give its 4′-O-β-D-glucoside as the major product in addition to its 3-O-β-D-glucoside by a plant glucosyltransferase from Phytolacca americana expressed in recombinant Escherichia coli. This enzyme transformed pterostilbene to its 4′-O-β-D-glucoside, and converted pinostilbene to its 4′-O-β-D-glucoside as a major product and its 3-O-β-D-glucoside as a minor product. An analysis of antioxidant capacity showed that the above stilbene glycosides had lower oxygen radical absorbance capacity (ORAC) values than those of the corresponding stilbene aglycones. The 3-O-β-D-glucoside of resveratrol showed the highest ORAC value among the stilbene glycosides tested, and pinostilbene had the highest value among the stilbene compounds. The tyrosinase inhibitory activities of the stilbene aglycones were improved by glycosylation; the stilbene glycosides had higher activities than the stilbene aglycones. Resveratrol 3-O-β-D-glucoside had the highest tyrosinase inhibitory activity among the stilbene compounds tested.

The catalytic promiscuity of a new glycosyltransferase (UGT73AE1) from Carthamus tinctorius was explored. UGT73AE1 showed the capability to glucosylate a total of 19 structurally diverse types of acceptors and to generate O-, S-, and N-glycosides, making it the first reported trifunctional plant glycosyltransferase. The catalytic reversibility and regioselectivity were observed and modeled in a one-pot reaction transferring a glucose moiety from icariin to emodin. These findings demonstrate the potential versatility of UGT73AE1 in the glycosylation of bioactive natural products.

To explore the acceptor regioselectivity of OleD-catalyzed glucosylation, the products of OleD-catalyzed reactions with six structurally diverse acceptors flavonesnY (daidzein), isoflavones (flavopiridol), stilbenes (resveratrol), indole alkaloids (10-hydroxycamptothecin), and steroids (2- methoxyestradiol)- were determined. This study highlights the first synthesis of flavopiridol and 2-methoxyestradiol glucosides and confirms the ability of OleD to glucosylate both aromatic and aliphatic nucleophiles. In all cases, molecular dynamics simulations were consistent with the determined product distribution and suggest the potential to develop a virtual screening model to identify additional OleD substrates.

Plant-cultured cells of Catharanthus roseus converted trans-resveratrol into its 3-O-β-D-glucopyranoside, 40-O-β-D-glucopyranoside, 3-O-(6-O-β-D-xylopyranosyl)-β-Dglucopyranoside, and 3-O-(6-O-α-L-arabinopyranosyl)-β- D-glucopyranoside. The 3-O-(6-O-β-D-x

Family 1 glycosyltransferases are a group of enzymes known to embrace a large range of different substrates. This study devises a method to enhance the range of substrates even further by combining domains from different glycosyltransferases to gain impro

trans-Resveratrol-3-O-β-D-glucupyranoside (trans-piceid, 2) and trans-resveratrol-4′-O-β-D-glucupyranoside (trans-resveratroloside 3) are the naturally occurring O-glucoside conjugates of the polyphenolic stilbenoid trans-resveratrol 1. Recently, attention has been drawn towards the interesting biological properties of the glucoside conjugates 2 and 3 as well as those of the aglycone 1. The fact that only limited quantities can be obtained by extraction from natural sources has prompted the development of novel syntheses of 2 and 3, based on a convergent Heck-coupling strategy, which now conveniently allows for the preparation of multi-milligram to gram quantities of each.

Resveratrol 3-O-β-D-glucopyranoside (1) has been isolated from the seeds of Erythrophleum lasianthum (Caesalpinioidae, Leguminosae), a South African plant used in traditional medicine, and has shown antiplatelet aggregation activity. The synthesis of 1, related hydroxystilbenes, and their glucosides has been undertaken to provide larger quantities, for further biological evaluation, and has been accomplished via Wittig reactions followed by glucosylation under phase transfer catalysis.

(E)-3-(β-D-Glucopyranosyloxy)-4',5-dihydroxystilbene (resveratrol 3-β-D-glucoside, piceid), (Z)-2',3'-dihydroxy-3,4,4',5-tetramethoxystilbene (combretastatin A-1), (Z)-3'-hydroxy-3,4,4', 5-tetramethoxystilbene (combretastatin A-4), (Z)-2'-hydroxy-3,4,4',5-tetramethoxystilbene (combretastatin iso-A-4), α,β-dihydro-2',3'-dihydroxy-3,4,4',5-tetramethoxystilbene (combretastatin B-1), the corresponding glucosides, and related compounds have been synthesized via Wittig reactions followed by,glucosylation under phase-transfer catalysis. Most of the compounds synthesized have been tested with respect to biological activity (cytostatic, cytotoxic, antimitotic, neurotoxic, antiplatelet aggregation activity).