Possible anti-tumour promoting properties of traditional Thai food items and some of their active constituents.

From a viewpoint of cancer chemoprevention, possible anti-tumour promoting properties of daily food items and some of their active constituents have been investigated by a convenient in-vitro assay, the Epstein-Barr virus (EBV) activation test. In a screening test for the inhibitory activity toward EBV activation by 40 methanol extracts from Thai edible plants used for flavours, condiments or folk medicines, more than three-quarters of the total were found to possess inhibitory activities. Significantly, the ratio of activity-exhibiting plants was about three times higher than that of Japanese common vegetables and fruits previously studied. The two plant families of Zingiberaceae and Rutaceae, in particular, were suggested to be promising sources for highly effective anti-tumour promoters. Hitherto, geranial (Cymbopogon citratus, Gramineae), cardamonin (Boesenbergia pandurata, Zingiberaceae). curcumin (Zingiber cassumunar, Zingiberaceae) and 1-acetoxychavicol acetate (Languas galanga, Zingiberaceae) have been idenflfied as the acfive constituents of strongly active plants in the tumour promoter-induced EBV activation test. They showed more potent inhibitory activities than the representative anti-tumour promoters such as β-carotene or quercetin. The high potential of the traditional food items of Thailand in the search for potent anti-tumour promoters is described in this article.