Two new spirobiflavonoids from Abies chensiensis with moderate NO production inhibitory activity.

Phytochemical investigation of the aerial parts of Abies chensiensis afforded two new (compounds 2 and 3) and 27 known compounds, including the related compound larixinol ( 1). The structures of spirobiflavonoids 1- 3 were established using 1D and 2D NMR spectroscopic techniques. In addition, the structure of larixinol ( 1) was confirmed by X-ray crystallographic analysis. Compounds 1- 3 were evaluated for inhibitory activities against LPS-induced NO production in macrophages. Larixinol ( 1) showed moderate effects, with an IC(50) value of 60.0 microg/mL. In addition, it did not show any cytotoxicity on RAW 264.7 macrophages at 100 microg/mL. Georg Thieme Verlag KG Stuttgart, New York.