Cancer chemopreventive activity of carotenoids in the fruits of red paprika Capsicum annuum L.

Capsanthin (1) and related carotenoids (2-7) isolated from the fruits of red paprika Capsicum annuum L. showed potent in vitro anti-tumor-promoting activity with inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). Among them, capsanthin diester (3) and capsorbin diester (5) showed strong inhibitory effects. Furthermore, casanthin (1), capsanthin 3'-ester (2) and capsanthin 3,3'-diester (3), major carotenoids in paprika, exhibited potent anti-tumor-promoting activity in an in vivo mouse skin two-stage carcinogenesis assay using 7, 12-dimethylbenz[a]anthracene as an initiator and TPA as a promoter.