A new cryptic irritant and cocarcinogen from seeds of Croton sparciflorus

In recent years the genus Croton has been of particular interest following the isolation of 11 different 12,13-diesters of the polyfunctional diterpene phorbol (1a), from the seed oil of Croton tiglium; these compounds represent its toxic, irritant and cocarcinogenic principles [1]. In addition, croton oil contains what is called “cryptic” cocarcinogens of the phorbol-12,13,20-triester type [1]. The structurally related but non-irritant diterpene ester 20-acetoxy-9-hydroxy-13,15-seco-4α-tigliatriene-(1,6,14)-dione-(3,13) [2] and crotofolin A have been isolated from C. rhamnifolius [3] and from C. corylifolious L. [4], respectively.