Definition - What does Stilbenes mean?
Stilbenes are naturally occurring compounds found in many plant families, including Vitis vinifera L. They include resveratrol and viniferins and are found in the woody organs of the stems, roots and canes and also in the leaves and fruit. They work as phytoalexins in the grape as a resistance against some pathogens and stress.
WineFrog explains Stilbenes
Stilbenes are naturally existing organic compounds found in the grape vine and are later imparted into wine from the grapes. Resveratrol (3, 5, 4-trijydroxystilbene) is one example and detectable in wine and in higher quantities in red wines. It has been shown to be an active ingredient that can reduce heart disease.
Viniferins are another form (an isomer) of resveratrol which acts as a protector of aromatic alcohols in wine.
As grape vines are typically grown under stressful conditions in order to grow quality fruit for quality wines, they have naturally developed resistant properties so they can endure stress. The production of stilbenes is a prime example of how vines are able to survive in harsh conditions like drought and in harsh climatic conditions and poor soils where other plants would die.