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

Abstract

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), 6ʹʹ‐O‐galloylgaylussacin sodium salt (2), 6ʹʹ‐O‐galloylgaylussacin (3), 4ʹ‐O‐[β‐D‐glucopyranosyl‐(1→6)‐glucopyranosyl]oxy‐2ʹ‐hydroxy‐6ʹ‐methoxydihydrochalcone (4), gaylussacin (5), pinosilvin 3‐O‐β‐D‐glucopyranoside (6), myricetin‐3‐O‐(2ʹʹ‐O‐galloyl)‐α‐L‐rhamnopyranoside (7), myricetin‐3‐O‐(3ʹʹ‐O‐galloyl)‐α‐L‐rhamnopyranoside (8), myricetin‐3‐O‐α‐L‐rhamnopyranoside (9), quercitrin (10), myricetin‐3‐O‐β‐D‐glucopyranoside (11), myricetin‐3‐O‐β‐D‐galactopyranoside (12), quercetin 3‐O‐α‐L‐arabinopyranoside (13), myricetin‐3‐O‐2ʹʹ‐O‐galloyl)‐α‐L‐arabinopyranoside (14), (+)‐gallocatechin (15), (‐)‐epigallocatechin (16), and 3,3’,4’‐trimethoxyellagic acid 4‐O‐β‐D‐glucopyranoside (17) by the analysis of HRESIMS, 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 ± 1.38 to 35.12 ± 2.53 µM, compared to a positive control (dexamethasone) with an IC50 value of 15.37 ± 1.42 µM.