Xanthones with anti-tumor activity isolated from Securidaca inappendiculata

Abstract

A new xanthone, 1,2-dihydroxy-6,7,8-trimethoxyxanthone, together with ten known xanthones and nine other compounds was isolated from the stem of Securidaca inappendiculata. The structure of the new compound was elucidated based on spectroscopic data analyses, and other compounds were identified by comparison with data from the literature. The anti-tumor activities of the xanthones were evaluated by MTT assay on human lung adenocarcinoma epithelial cell line A549, and a primary structure–activity relationship analysis was carried out based on results from MTT assay. It is revealed that all the xanthones possessed anti-tumor activity in vitro in a concentration-dependent manner. The IC50 values varied a lot among xanthones. 1,7-Dihydroxy-3,4-dimethoxyxanthone was proved to be the most efficient anti-tumor agent with IC50 of 50.66 μM, while 1,3,7-trihydroxy-2,8-dimethoxyxanthone and 1,7-dihydroxyxanthone possessed the weakest activities. The structure–activity relationship analysis revealed that the anti-tumor activity of xanthones was affected mostly by the position and number of hydroxyl and methoxyl groups. Free hydroxyl and ortho-methoxyl groups were believed to possess important potentials to the activity.