*2.12.1. Plectranthus ambiguus*

The plant afforded a series of tetracyclic phyllocladane-type (= 13*β*-kaurane) diter-penoids: (16*R*)-2α-senecioyloxy-3α-acetoxyphyllocladan-16,17-diol (**95**), (16*R*)-2α-senecioyloxy-3α,17 diacetoxy-16-hydroxyphyllocladane (**96**), (16*R*)-2α-isovaleroyloxy-3α-acetoxyphyllocladan-16, 17-diol (**97**), (16*R*)-2α-isovaleroyloxy-3α,17-diacetoxy-16-hydroxyphyllocladane (**98**), (16*R*)-3α-acetoxyphyllocladan-16,17-diol (**99**), (16*R*)-2α-senecioyloxy-16,17-dihydroxyphyllocladan-3-one (**100**), and (16*R*)-2α,3α-diacetoxyphyllocladan-16,17-diol (**101**). The authors discriminated between phyllocladane and *ent*-kaurane tetracyclic skeletons after extensive spectroscopic investigation as well as chemical transformations [48, 49].
