Methylthio Acetic Acid in Japanese Pickling Melon as a Potential Chemopreventive Agent against in Vitro and in Vivo Carcinogenesis System

The cancer preventive activity of vegetables have received a great deal of attention from cancer researchers and study fields. During our investigation of the active preventive properties from an excellent source of vegetables and fruits, useful bioassay-guided led to the screening of traditional natural materials. Katsura-uri, an heirloom vegetable in Kyoto (Japanese pickling melon; Cucumis melo var.conomon), is an unsweet fruit, possesses an intense muskmelon-like fragrant and serve traditional vegetable tools for healthy purpose. The application of a new screening procedure which utilizes the synergistic effect of short-chain fatty acids and tumor-promoting diterpene esters, TPA enabled rapid and easy detection of naturally occurring substances (anti-tumor promoters) with inhibition of Epstein-Barrvirus (EBV) activation, using human lymphoblastoid cells. In the course of these studies, female ICR mouse (6 weeks of age) were treated topically with single dose of DMBA as initiator, followed by TPA twice a weekly for 20 weeks as promoter. Tumor incidence were 100% with 6 to 7 per mouse at end of experiment as positive control group. In our observation, Katsura-uri and its components, (methylthio) acetic acid (MTA) treated group cause about 60 – 70% reduction in the average number of tumors per mouse after 20 weeks of experiment, respectively. Taken together, our preliminary data suggest that the ability of Katsura-uri to suppress promoting stages is valuable for tumor growth inhibition

and provide a basis for further development of these botanical supplements for human cancer chemoprevention