Undescribed Phenolic Glycosides from Syzygium attopeuense and Their Inhibition of Nitric Oxide Production

Four undescribed phenolic glycosides including three stilbene derivatives (1 and 3) and sodium salt of 3 (2), and a chalcone glycoside (4), together with thirteen known compounds (5-17) were isolated from the leaves of Syzygium attopeuense (Gagnep.) Merr. & L.M.Perry. Their chemical structures were elucidated to be (Z)-gaylussacin (1), 6 & PRIME;& PRIME;-O-galloylgaylussacin sodium salt (2), 6 & PRIME;& PRIME;-O-galloylgaylussacin (3), 4 & PRIME;-O-[& beta;-D-glucopyranosyl-(1 & RARR;6)-glucopyranosyl]oxy-2 & PRIME;-hydroxy-6 & PRIME;-methoxydihydrochalcone (4), gaylussacin (5), pinosilvin 3-O-& beta;-D-glucopyranoside (6), myricetin-3-O-(2 & PRIME;& PRIME;-O-galloyl)-& alpha;-L-rhamnopyranoside (7), myricetin-3-O-(3 & PRIME;& PRIME;-O-galloyl)-& alpha;-L-rhamnopyranoside (8), myricetin-3-O-& alpha;-L-rhamnopyranoside (9), quercitrin (10), myricetin-3-O-& beta;-D-glucopyranoside (11), myricetin-3-O-& beta;-D-galactopyranoside (12), quercetin 3-O-& alpha;-L-arabinopyranoside (13), myricetin-3-O-2 & PRIME;& PRIME;-O-galloyl)-& alpha;-L-arabinopyranoside (14), (+)-gallocatechin (15), (-)-epigallocatechin (16), and 3,3',4'-trimethoxyellagic acid 4-O-& beta;-D-glucopyranoside (17) by the analysis of HR-ESI-MS, 1D and 2D NMR spectra in comparison with the previously reported data. Compounds 1-3, 5, and 6 significant inhibition of NO production in LPS-activated RAW264.7 cells, with IC50 values ranging from 18.37 & PLUSMN;1.38 to 35.12 & PLUSMN;2.53 & mu;M, compared to a positive control (dexamethasone) with an IC50 value of 15.37 & PLUSMN;1.42 & mu;M.

Automated summary

Four undescribed phenolic glycosides including three stilbene derivatives and a chalcone glycoside, as well as thirteen known compounds, were isolated from the leaves of Syzygium attopeuense. Their chemical structures were determined and compounds 1-3, 5, and 6 showed significant inhibition of NO production in LPS-activated RAW264.7 cells.