phytosterols and Cocarcinogenesis

Inhibitory activity against 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced inflammation in mice was observed in the methanol extract of rice bran and gamma-oryzanol. The active components of rice bran, sitosterol ferulate, 24-methylcholesterol ferulate, cycloartenol ferulate and 24-methylenecycloartanol ferulate inhibited markedly the TPA-induced inflammation in mice. The 50% inhibitory dose of these compounds for TPA-induced inflammation was 0.2-0.3 mg/ear. Furthermore, cycloartenol ferulate markedly inhibited the tumor-promoting effect of TPA in 7,12-dimethylbenz[a]anthracene-initiated mice.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Anticarcinogenic Agents; Carcinogens; Cocarcinogenesis; Dermatitis, Contact; Female; Hypolipidemic Agents; Mice; Mice, Inbred ICR; Oryza; Phenylpropionates; Phytosterols; Plant Extracts; Skin; Skin Neoplasms; Sterols; Tetradecanoylphorbol Acetate; Triterpenes

A mutant safflower oil, rich in oleic acid, was used for a critical test of the hypothesis that polyunsaturated fats act as co-carcinogens. Weanling female rats were each given 5 mg of 7,12-dimethylbenz(alpha)anthracene. They were then pair-fed diets containing 20%, by weight, of conventional high-linoleic safflower oil; a mutant high-oleic safflower oil; or coconut oil. Half of each group received supplementary DL-alpha-tocopherol. Tumors were identified by two observers, by palpation. Data on incidence of tumors and on numbers of tumors per affected rat led to similar conclusions. At 16 weeks, there were significant differences when supplementary tocopherol was included in the diet: the group fed high-oleic safflower oil had more tumors than the group fed coconut oil. This difference was not seen in the absence of supplementary tocopherol. When the data for tocopherol-supplemented and unsupplemented subgroups were combined, the high-oleic safflower oil group had significantly more tumors than did the coconut oil group. The high-linoleic safflower oil group was not significantly different from either of the other groups. In all groups, histologic examination of the largest tumor in each rat revealed more benign tumors, mostly duct papillomas, than carcinomas.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Animals; Benz(a)Anthracenes; Body Weight; Carcinoma, Intraductal, Noninfiltrating; Carcinoma, Papillary; Cocarcinogenesis; Cocos; Dietary Fats; Drug Synergism; Female; Linoleic Acids; Mammary Neoplasms, Experimental; Oils; Oleic Acids; Phytosterols; Rats; Safflower Oil; Vitamin E