MODULATION OF AFLATOXIN B-1 ACTIVATED PROTEIN-KINASE-C BY PHENOLIC-COMPOUNDS

Several natural phenolic compounds were tested in vitro for their effe ct on the activity of protein kinase C isolated from liver cytosol, pa rticulate and nuclear fractions of normal and aflatoxin B-1 treated ra ts. Quercetin and kaempferol inhibited the enzyme activity of all thes e fractions at very low dose levels. These phenolics were particularly effective in inhibiting the elevated enzyme activity following aflato xin B-1 administration. Ellagic acid and curcumin were found to be inh ibitory only towards particulate enzymes obtained after carcinogen tre atment, while curcumin and rutin were moderately active against nuclea r enzymes. Constitutive activation of protein kinase C can drive the c ell to a proliferative state, thereby initiating the process of carcin ogenesis, however, suppression of this activation by phenolic compound s may be an effective way to control carcinogenesis. (C) 1997 Elsevier Science Ireland Ltd.