Constituents from Vitex negundo var. heterophylla and their inhibition of nitric oxide production.

An iridoid glucoside, 10-p-hydroxybenzoyl-6β-hydroxyiridoid 1-O-β-D-(6'-O-p-hydroxybenzoyl)-glucopyranoside (1), and a phenol glucoside, 4-hydroxyphenethanol 3-O-β-D-(6'-O-p-hydroxybenzoyl)-glucopyranoside (2), along with nine known compounds (3-11) were isolated from the dried leaves of Vitex negundo var. heterophylla. Their structures were elucidated by extensive analysis of NMR spectra. All of the isolated compounds were evaluated for their inhibitory effects on nitric oxide production in RAW 264.7 macrophages. Compounds 2 and 3 exhibited obvious inhibitory effects on NO production with IC50 values of 30.76 and 49.89 μM, respectively. Molecular docking studies of compounds 2 and 3 with nitric oxide synthase (NOS) further confirmed the above results.