Chemical constituents of Hoya buotii Kloppenb.

Chemical investigation of the dichloromethane extracts of Hoya buotii Kloppenb. afforded taraxerone (1), taraxerol (2), a mixture of β-sitosterol (3a) and stigmasterol (3b) in about 2:1 ratio, and a mixture of α-amyrin cinnamate (4a) and β-amyrin cinnamate (4b) in about 1:2 ratio from the stems; 1, 2, and 3a from the roots; a mixture of 4a and 4b in about 3:2 ratio from the flowers; and 3a, squalene (5) and saturated hydrocarbons from the leaves. The structures of 1-5 were identified by comparison of their NMR data with those reported in the literature.