Crocin and crocetin derivatives inhibit skin tumour promotion in mice

The addition of 100 μg/mL of a 50% EtOH extract of Crocus sativus (ECS) exhibited significant inhibitory effects on EBV-EA activation and preserved the high viability of Raji cells. The attenuating effect of ECS was dose- dependent. The oral administration of ECS demonstrated an inhibitory effect on two-stage carcinogenesis of mouse skin papillomas, using DMBA as an initiator and TPA as a promoter. Crocetin gentiobiose glucose ester and crocetin di-glucose ester were less potent than crocin in inhibiting the EBV- EA induction effect. When crocin was applied before each TPA treatment, it delayed the formation of papillomas; only about 10% of mice bore papillomas at 9 weeks of promotion and after 13 weeks of promotion 20% of mice still bore no papilloma. The effect of crocin was not mimicked by gentiobiose or glucose alone.