Quassinoids and alkaloids from the stems of Picrasma quassioides with nitric oxide inhibitory activity

•Two new quassinoids and a new alkaloid were obtained from the stems of Picrasma quassioides.•The new structures were elucidated by 1D, 2D NMR, IR, HRESIMS, specific rotation and ECD data.•Compound 10 showed nitric oxide inhibitory effects against LPS-stimulated RAW 264.7 cells with IC50 value of 96.1 μM.