Chemical constituents from the aerial parts of Gynura bicolor.

Gynura bicolor (Willd.) DC., is used in folk recipes for the treatment of diabetes mellitus in Jiangsu, Zhejiang and Sichuan province in the south of China. A previous pharmacological study proved that the plant showed significant hypoglycemic activity on normal and alloxan-diabetic mice. In this study, two terpenes, four megastigmane-type norisoprenoids and two glycosides were isolated from the aqueous ethanolic extract of the aerial parts of Gynura bicolor and characterized mainly by NMR spectroscopy and mass spectrometry. Thes e compounds were isolated for the first time from this plant, and no evidence could be found for the previous reported presence of megastigmane-type norisoprenoids in the genus Gynura.