Inhibitory Effect of Alkane-6,8-Diols, the Components of Safflower, on Tumor Promotion by 12-O-Tetradecanoylphorbol-13-Acetate in Two-Stage Carcinogenesis in Mouse Skin

Erythro-alkane-6,8-diols were isolated from the flowers of Carthamus tinctorius. 12-0-Tetradecanoylphorbol-13-acetate (TPA, 1 ug/ear), a tumor-promoting agent, was applied to the ears of mice to induce inflammation. Of 8 alkane-6,8-diols assayed, the C₂₇, C₃₁, C₃₂, C₃₃ and C₃₅ alkane diols inhibited the inflammation. The 50% inhibitory dose of these compounds for TPA-induced inflammation was 0.5–0.7 mg/ear. However, C₂₁, C₂₃ and C₂₅ alkane-6,8-diols were found to have no effect. Furthermore, the mixture of erythro-alkane-6,8-diols from the flowers of C. tinctorius markedly suppressed the promoting effect of TPA on skin tumor formation in mice following initiation with 7,12-dimethylbenz[a]anthracene.