Carthami flos extract and its component, stigmasterol, inhibit tumour promotion in mouse skin two‐stage carcinogenesis

An antitumour‐promoting activity in two‐stage carcinogenesis, is found in the methanol extract of the Carthami Flos (Carthamus tinctorius L.; Compositae), which is a traditional Chinese medicine and natural pigment of rouge additivies in certain Asian countries. From these active fractions, δ5‐ and δ7‐sterol fractions were separated. The separation was examined for inhibitory activity against TPA‐induced inflammatory ear oedema in mice. Stigmasterol (71% in the mixture) was the most abundant of 14 sterols identified in the δ5‐sterol fraction. Schottenol (70% in the mixture) constituted the dominant sterol of the δ7‐sterol fraction. Furthermore, stigmasterol markedly inhibited tumour promotion in two‐stage carcinogenesis experiments.