Antifungal Activities of a Grapevine Byproduct Extract Enriched in Complex Stilbenes and Stilbenes Metabolization by .

Grapevine co-products, as canes, represent a source of compounds of interest to control vineyard diseases with a sustainable approach. We chose to study an extract that we produced from grapevine trunk and roots. This extract, enriched in complex stilbenes, strongly reduced mycelial growth and spore germination of , the fungal agent causing gray mold. The most active stilbenes were resveratrol, r-viniferin, and ε-viniferin. This grapevine extract also inhibited the production of Botrytis laccases. Conversely, Botrytis secretome metabolized resveratrol into δ-viniferin and pallidol (2 dimers); and ε-viniferin, a dimer, into hopeaphenol, r-viniferin, and r2-viniferin (3 tetramers). r-Viniferin and hopeaphenol (2 tetramers) were not metabolized. The biotransformed extract maintained an effective antimycelial activity. This study provides evidence that a grapevine extract enriched in oligomerized stilbenes exerts different anti-Botrytis activities, notwithstanding the ability of the fungus to metabolize some stilbenes.