摘要：An alcoholic extract of Phyllanthus amarus ( P. amarus ) was found to inhibit cytochrome P450 (P450) enzymes both in vivo as well as in vitro . This was studied using specific resorufin derivatives, as substrate for isoenzymes in the P450 super family. Concentration needed for 50% inhibition of 7-ethoxyresorufin- O -deethylase (EROD), CYP1A1 was 4.6 μg/ml while concentration needed for 7-methoxyresorufin- O -demethylase (MROD) CYP1A2 was 7.725 μg/ml and 7-pentoxyresorufin- O -depentylase (PROD), CYP2B1/2 was found to be 4.18 μg/ml indicating that the extract inhibited the P450 enzymes at very low concentration. Extract also inhibited the activity of aniline hydroxylase (an indicator of CYP 2E1 activity, IC50 50 μg/ml) and aminopyrine demethylase (an indicator of CYP 1A, 2A 2B, 2D and 3A activity, IC50 >1000 μg/ml). Oral administration of the extract was also found to reduce the elevated P450 enzyme activities produced by phenobarbitone by 50% at 250 mg/kg body weight. The implication of these results on the inhibition of carcinogenesis produced by the extract is discussed.
