Antifungal Activity of Resveratrol Derivatives against Candida Species

trans-Resveratrol (1a) is a phytoalexin produced by plants in response to infections by pathogens. Its potential activity against clinically relevant opportunistic fungal pathogens has previously been poorly investigated. Evaluated herein are the candidacidal activities of oligomers (2a, 3–5) of 1a purified from Vitis vinifera grape canes and several analogues (1b–1j) of 1a obtained through semisynthesis using methylation and acetylation. Moreover, trans-ε-viniferin (2a), a dimer of 1a, was also subjected to methylation (2b) and acetylation (2c) under nonselective conditions. Neither the natural oligomers of 1a (2a, 3–5) nor the derivatives of 2a were active against Candida albicans SC5314. However, the dimethoxy resveratrol derivatives 1d and 1e exhibited antifungal activity against C. albicans with minimum inhibitory concentration (MIC) values of 29–37 μg/mL and against 11 other Candida species. Compound 1e inhibited the yeast-to-hyphae morphogenetic transition of C. albicans at 14 μg/mL

Stilbenoid-Enriched Grape Cane Extracts for the Biocontrol of Grapevine Diseases

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Vitis vinifera canes, a source of stilbenoids against Spodoptera littoralis larvae

Stilbenes are constitutively accumulated in grape canes at a high concentration of about 10 g kg(-1) DW. Some of these compounds have antimicrobial activity and are involved in grapevine defence in leaves and fruits, acting as phytoalexins. In this work, we studied their insecticidal effects against Spodoptera littoralis larvae by using an extract from grapevine canes containing 27% (w/w) of total stilbenes and the major ones isolated from this extract (E-piceatannol, E-resveratrol, isohopeaphenol, E-epsilon-viniferin and E-vitisin B). The stilbenes isolated from the grapevine extract did not show any significant antifeedant effect or acute toxicity, but they did cause chronic mortality to the larvae population of an important polyphagous pest, S. littoralis. The tetramer, E-vitisin B, appeared to be the most effective compound with LC50 and LC90 values of 134 and 298 mu g cm(-2), respectively. Significant synergic relationships were found between some stilbenes, resulting in a significant increase in the insecticidal efficacy of the mixture of these substances. Taken together, these results suggest that grapevine canes are a good source of active substances for the development of botanical insecticides