Stilbene derivatives from two species of Gnetaceae.
Five new stilbene oligomers (gnemonols A, B and C, gnemonoside E and gnetal) were isolated together with 2b-hydroxyampelopsin F and gnetin E from Gnetum gnemon and G. gnemonoides. The structures of the compounds were elucidated on the basis of spectral evidence.
Stilbenoids in lianas of Gnetum parvifolium.
Five new stilbene dimers were isolated from the lianas of Gnetum parvifolium in addition to known stilbenoids. The structures of the compounds were established on the basis of spectroscopic evidence, including long-range coupling and nuclear Overhauser effect experiments, in NMR spectrum. Among the isolates, 2b-hydroxyampelopsin F showed potent inhibitory activity in the Maillard reaction.
Gnetulin, a dimer of 3′,4,5′-trihydroxy-3-methoxystilbene from gnetum ula
Gnetulin, a dimer of 3′,4,5′-trihydroxy-3-methoxystilbene, isolated from Gnetum ula, has been assigned structure and relative configuration (1) on the basis of long range COSY and NOE difference experiments on the peracetate (2).