A51

Ultraviolet(UV) light is the most common cause of skin

cancer in humans and it is very acute problem in our life

style during living. Several effects of UVB(290-320 nm) are thought to contribute to skin carcinogenesis and generation of free radicals and related oxidants produced by UVB exposure.Tabebuia avellanedae (Bignoniaceae)(TA), which is native in South America from Brazil to northern Argentina, is well known in traditionalfolk medicne used for the treatment of various disease during five hundred years. The inner bark of this plant produced in Brazil is distributed in Asia and Japan as a healthy purpose herb tea. Previously, we reported that extract essense of TA(TA ess.) and including naphthoquinones type compounds, NQ801, inhibited TPA-induced in vitro assay for chemopreventive potency and also inhibited TPA-induced in vivo assay on two-stage mouse skin test. We have now extended these investigations to a new tumorigenesis model in which we initiated the tumors with UVB irradiation and promoted with 1.7 nmol of TPA in SENCAR mice. These tumor -free mice, which had a high risk of developing skin tumors, using these experimental systems, were then treated drinking with TA ess. Oral feeding of 0.0025 % of TA ess., two weeks before and after tumor initiation resulted in a significant reduction in tumor incidence (40 %) accompanied by an extension(> 20 %) of the tumor latency and also decrease papilloma multiplicity. These results provide a basis for further development of TA ess. against sunlight-induced skin cancer in humans.

Citation Information: Cancer Prev Res 2008;1(7 Suppl):A51.

Seventh AACR International Conference on Frontiers in Cancer Prevention Research-- Nov 16-19, 2008; Washington, DC