Chemical Components from Phaeanthus vietnamensis and Their Inhibitory NO Production in BV2 Cells

Phaeanthus vietnamensis Bân is a well-known medicinal plant which has been used for the treatment of various inflammatory diseases in traditional medicine. Using various chromatographic methods, three new compounds, (7S,8R,8'R)-9,9'-epoxy-3,5,3',5'-tetramethoxylignan-4,4',7-triol (1), 8α-hydroxyoplop-11(12)-en-14-one (5), and (1R,2S,4S)-4-acetyl-2-[(E)-(cinnamoyloxy)]-1-methylcyclohexan-1-ol (12) along with twelve known compounds were isolated from the leaves of P. vietnamensis. Their chemical structures were elucidated by physical and chemical methods. All compounds were evaluated for the inhibitory activities of nitric oxide production in LPS-stimulated BV2 cells. As the results, compound 6 showed the most potent inhibitory activity on LPS-stimulated NO production in BV2 cells with the IC₅₀ values of 15.7 ± 1.2 μm. Compounds 2, 7, and 8 significantly inhibited inflammatory NO production with IC₅₀ values ranging from 22.6 to 25.3 μm.