δ-Viniferin is a resveratrol dehydrodimer. It is an isomer of epsilon-viniferin. It can be isolated from stressed grapevine (Vitis vinifera) leaves. It is also found in plant cell cultures. or in wine. It can also be found in Rheum maximowiczii. It is a grapevine phytoalexin following stresses like fungal infection (by Plasmopara viticola, the agent of downy mildew), UV light irradiation or ozone treatment. Botryosphaeria obtusa, a pathogen responsible for the black dead arm disease of grapevine, has also been shown to be able to oxidise wood δ-resveratrol into delta-viniferin. In cell cultures, the use of methyl jasmonate and jasmonic acid as elicitors stimulates δ-viniferin biosynthesis. Delta-viniferin can also be produced from resveratrol by human PTGS1 (COX-1, cyclooxygenase-1) or from trans-resveratrol and (−)-epsilon-viniferin by horseradish peroxidase.
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