Resveratrol oligomers

Sotheeswaran S, Pasupathy V. 1993. Distribution of resveratrol oligomers in plants. Phytochem 32 1083-1092. 

Ito, X, Akao, Y., Yi, H., Ohguchi, K., Matsumoto, K., Tanaka, X, linuma, M., Nozawa, Y. (2003). Antitumor effect of resveratrol oligomers against human cancer cell lines and the molecular mechanism of apoptosis induced by vaticanol C. Carcinogesis, 24, 1489-1497. 

The synthesis of /raw5-resveratrol oligomers requires the set of enzymes that yield trows-resveratrol from the phenylpropanoid precursor, p-coumaryl-CoA and malonyl-CoA, and then the oxidative coupling of resveratrol units by a phenol oxidase, which is presumably a class HI plant peroxidase [138,139], In fact, class HI plant peroxidases, such as that purified from grapevines, are able to oxidize frvms-resveratrol with values of 17-93 pM for H2O2 concentrations ranging from 0.1 to 5.0 mM at pH 4.0 [58], and with values of 11.9 pM" s, at the same pH [35,58]. 

Other possible coupling modes of /ra/ts-resveratrol radicals might explain the formation of viniferins in planta. For example, /raw5-resveratrol oligomers found in nature may also arise from the coupling of the mesomeric species (Mp + Mcz) (Scheme XX). 

Both (Mp + Mco) (Scheme XVII) and (Mp + Mc2) (Scheme XX) coupling modes in the synthesis of resveratrol oligomers are totally compatible with the nature of the peroxidase-catalyzed reaction. The reasons why the above coupling modes are favored in vivo (to permit the formation of s-viniferin), whereas the (Mp + Mo4 ) coupling mode (Scheme XVI) is favoured in vitro, is a question which deserves further research. 

Artogomezianol (527) and andalasin A (543) from the roots of Artocarpus gomezianus showed moderate tyrosinase inhibitory activity [274]. Resveratrol oligomers from dipterocarpaceae plants were also reported to have inhibitory effects on murine tyrosinase activity. The SARs revealed that the double bond in the stilbene skeleton was critical for the inhibition, and also that with increased molecular size, the inhibitory potency decreased [529]. 

All the mentioned transformation and oxidative coupling reactions provide us information of the reactivity based on the biogenetic pathway and further confirmation of absolute structures of the resveratrol oligomers. 

The quaternary carbons of C-l and C-9 (not attached to a double bond) in resveratrol exhibited signals at 8 130-136 and 8 141-149, respectively, after polymerization. The quaternary carbons attached to a hydroxy group in resveratrol oligomers showed signals at 8 155-162. 

RESVERATROL OLIGOMERS STRUCTURE, CHEMISTRY, AND BIOLOGICAL ACTIVITY... 

The resveratrol oligomers are composed of a diverse assemblage of polyphenolic compounds derived from the trihydroxystilbene monomer resveratrol (1). Previously, in a review by Sotheeswaran and Pasupathy [7], the authors proposed a simple dichotomous classification scheme for categorizing these compounds based on a single structural feature. Under... 

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