Inhibitory effect of Perilla leaf extract and luteolin on mouse skin tumor promotion.

In the present study, the effects of perilla leaf extract (PLE) and luteolin on 7,12-dimethylbenz[a]anthracene (DMBA)- and 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced skin papillomas in mice were investigated. Topical application of PLE prior to TPA treatment in DMBA-initiated mouse skin resulted in a significant reduction in tumor incidence and multiplicity. An even more potent preventive effect was observed with topical application of luteolin, which we previously identified as an antiinflammatory constituent. PLE was dissolved in drinking water at a 0.05% dose and mice ingested it ad libitum; no significant difference was observed in tumor incidence or multiplicity but there was a significant reduction in tumor volume between the PLE-treated and untreated groups. These results suggest that PLE has potent antipromotion activity and ingesting it as a daily food may provide a beneficial chemopreventive effect.