Identification and nitric oxide production inhibitory activity of phenolic derivatives from the trunks of Gnetum latifolium .

Phytochemical investigation of the trunks from Gnetum latifolium led to the isolation of a novel phenolic glucoside, 2 E -2,4-di-(3,4-dihydroxyphenyl)but-2-en-1-yl- O - β -D-glucopyranoside ( 1 ), along with five known stilbene derivatives ( 2-6 ). Their structures were determined mainly using high-resolution electrospray ionisation mass spectrometry and nuclear magnetic resonance spectroscopic analyses, followed by comparisons of observed spectral data with reported values. The novel compound 1 in G. latifolium was found to be useful as a chemotaxonomic marker. Biological evaluation revealed that compound 6 had remarkable inhibitory effects on nitric oxide production, with a half-maximal inhibitory concentration (IC 50 ) value of 4.85 ± 0.20 µM, which was much higher than that of the positive control dexamethasone (IC 50 = 14.20 ± 0.54  µ M).