INHIBITORY EFFECT OF NATURAL CAROTENOIDS ON EPSTEIN-BARR-VIRUS ACTIVATION ACTIVITY OF A TUMOR PROMOTER IN RAJI CELLS - A SCREENING STUDY FOR ANTITUMOR PROMOTERS

As a screening study for anti-tumor promoters, 51 carotenoids with div erse structures were examined for their inhibitory effects on the Epst ein-Barr virus activation activity of 12-O-tetradecanoylphorbol-13-ace tate (TPA) in Rail cells. The results showed that most of the caroteno ids exhibited inhibitory activity, and in general, no cytotoxicity on Rail cells was observed in the assay. Among the carotenoids, beta-cryp toxanthin, lutein, and lactucaxanthin showed the strongest inhibitory activity, superior to the well known anti-tumor promoter. beta-caroten e. Heteroxanthin, peridinin, and halocynthiaxanthin showed cytotoxicit y at the high concentration (1000 molar ratio per TPA), but indicated a strong inhibitory effect at the lower concentrations, which were onl y weakly toxic (500 and 100 molar ratios). Based on these results, the essential moiety for the activity of carotenoids was considered to be the 3-hydroxy-epsilon-end group.