The amazonian climber Gnetum venosum contains, besides the stilbenes r
esveratrol and rapontigentin (3-methoxyresveratrol), oxidative stilben
e oligomers such as the dimer gnetin C and the trimers gnetin E, gneti
n J (3''-hydroxygnetin E) and gnetin K (3''-methoxygnetin E). Gnetins
J and K are described for the first time. Oligomers of stilbenoids con
stitute a new class of condensed tannins.