Clerodane-type diterpenes and other constituents of Penianthus zenkeri

Twenty-four compounds were isolated from Penianthus zenkeri and their structures determined by spectroscopic and chemical studies. 6-Hydroxycolumbin, 6-hydroxyisocolumbin, penianthic acid methyl ester, 2β-3α-dihydroxy- 2,3,7,8α-tetrahydropenianthic acid lactone and the glycosides floribundic acid glucoside and zenkerin are new clerodanes or clerodane derivatives.