Kaempferol glycosides from the twigs of Cinnamomum osmophloeum and their nitric oxide production inhibitory activities

In the present study, ethanolic extract of twigs from Cinnamomum osmophloeum led to isolate nine kaempferol glycosides including two new kaempferol triglycosides that were characterized as kaempferol 3-O-β-d-xylopyranosyl-(1→2)-α-l-arabinofuranosyl-7-O-α-l-rhamnopyranoside (1) and kaempferol 3-O-β-d-xylopyranosyl-(1→2)-α-l-rhamnopyranosyl-7-O-α-l-rhamnopyranoside (2). The structures of these compounds were assigned by the application of 1D and 2D NMR spectroscopy and other techniques. Among these nine compounds, kaempferol 7-O-α-l-rhamnopyranoside (9) revealed inhibitory effect against LPS-induced production of nitric oxide in RAW 264.7 macrophages with an IC50 value of 41.2 μM. It also slightly reduced PGE2 accumulation by 26% at the concentration of 50 μM.

Graphical abstractTwo new kaempferol triglycosides (1 and 2) were isolated from the ethanolic extract of twigs of Cinnamomum osmophloeum, along with seven known kaempferol glycosides. Their structures were assigned by the application of 1D and 2D NMR spectroscopy and other techniques.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The chemical constituents of twigs of Cinnamomum osmophloeum were investigated. ► Two new kaempferol glycosides were isolated and identified by spectroscopic data and chemical evidence. ► Compound 9 revealed inhibitory effect against LPS-induced production of nitric oxide in RAW 264.7 macrophages.