Effect of Methanol Leaf Extract of Orthosiphon stamineus Benth . on Hepatic Drug Metabolizing Enzymes in Sprague Dawley (SD) Rats

Orthosiphon stamineus Benth. or locally known as Misai Kucing is widely used in Malaysia for treating hypertension, urinary system ailments and kidney stone disease. This study aims to study the in vitro effect of methanol extract of O. stamineus on aminopyrine N-demethylase, UDP-glucuronosyltransferase (UGT) and glutathione-S transferase (GST) activities in young male and female Sprague Dawley (SD) rat liver. Hepatocytes, liver microsomes and cytosolic liver fraction (S-9 fraction) from young male and female SD rats were used throughout the in vitro experiment to examine aminopyrine N-demethylase, UGT and GST activities. Results obtained showed that aminopyrine N demethylase activities in young male female and rat liver were not affected by methanol extract of O. stamineus except at 0.001 mg/ml (P 0.05) in female rats. However, most of the UGT and GST activities in young male and female SD rat liver were significantly decreased by methanol extract of O. stamineus treatment especially at the higher concentrations such as 0.1 mg/ml and 1 mg/ml as compared to their control group. In conclusion, concentrations of methanol extract of O. stamineus from 0.00001 mg/ml to 0.0001 mg/ml did not affect the activities of aminopyrine N-demethylase, UGT and GST in young male and female SO rat liver. Methanol extract of O. stamineus higher than 0.0001 mg/ml had a greater influence on UGT and GST activities than the aminopyrine N demethylase activities in SO rat liverand the effects were dose-dependent.