Skin irritant diterpene orthoesters of the daphnane type from Peddiea africana and P. Volkensii

Abstract

From roots of Peddiea volkensii (Thymelaeaceae) the irritant factors V1 and V2 and from roots of P. africana the irritant factor A1 were isolated. Their structures are the 9,13,14-ortho-(2,4,6-decatrienoates) of 5β-hydroxyresiniferonol-6α,7α-oxide (V1) and of 5β,12β-dihydroxyresiniferonol-6α,7α-oxide (A1) and the 12-O-acetate of the latter (V2). Factors V1 and V2 do not exhibit tumour-promoting activity in the standard initiation-promotion protocol on mouse skin, although V1 is a moderate irritant.