Screening of edible plants against possible anti-tumor promoting activity.

One hundred twenty-one species of edible plants (133 test-parts) were screened against possible anti-tumor promoting activity by an in vitro short-term assay system of inhibition of Epstein-Barr virus (EBV) activation induced by a phorbol-ester promoter, 12-O-hexadecanoylphorbol-13-acetate (HPA). The methanol-extracts (ME) of 14 species of the edible plants strongly inhibited the activation, 7 moderately and 12 weakly inhibited it. On partition of the randomly selected inactive ME (26 species) with ethyl acetate and water, 13 and 2 species were active, more or less, in the ethyl acetate and water soluble part, respectively. Thus, this result suggested that anti-tumor promoters occur in a wide variety of edible plants. The anti-tumor promoting activity in the crude extracts may be enhanced or reduced with co-occurring factors acting additively, synergistically or antagonistically.