| ABSTRACT: |
|
Naturally occurring plant phenols with antimutagenic and
anticarcinogenic activities were tested for their abilities to inhibit the
biochemical and biological effects of the potent tumor promoter
12-O-tetradecanoyl-phorbol-13-acetate (TPA) in mouse epidermis in vivo.
When applied topically to mouse skin, tannic acid (TA), ellagic acid, and
several gallic acid derivatives all inhibit TPA-induced ornithine
decarboxylase activity, hydroperoxide production, and DNA synthesis, three
biochemical markers of skin tumor promotion. Moreover, in the two-step
initiation-promotion protocol, the same phenolic compounds also inhibit
the incidence and yield of skin tumors promoted by TPA. TA is the most
effective of these treatments. Since they are already known to inhibit
tumor initiation, the plant phenols protecting against skin tumor
promotion by TPA may be universal inhibitors of multistage carcinogenesis.
TA and other polyphenols, therefore, might be valuable in cancer therapy
and/or prevention. |