ABSTRACT
The aim of this research was to evaluate the effects of Eurycoma longifolia root extract (ELE) on enzymes activity in thephase II drug metabolism on Sprague-Dawley (SD) rats, especially on uridine 5ʹ-diphospho-glucuronosyltransferase(UGT) activity, in vivo and in vitro. The UGT assay was performed as follows: for the in vivo study, the male SDrats were treated with ELE at doses ranging from 5 to 1,000 mg/kg b.w. and 5, 25, and 50 mg/kg b.w for acuteand sub-acute study, respectively. The ELE concentrations of 0.01 to 1,000 µg/ml were used for in vitro study. Thep-nitrophenol (pNP) that consumed in the glucuronidation process reflected the UGT activity and was calculated usingstandard curve of pNP. UGT enzyme activity was inhibited significantly (p < 0.01) by ELE extract in the male rat forboth acute and sub-acute experiments. ELE extract decreased the enzyme activity significantly (p < 0.01), at all theconcentrations tested in the in vitro experiment when compared to the negative control group. ELE had a lower activity(the IC50 of 0.74 µg/ml) as compared to Na diclofenac (positive control) with an IC50 of 0.17 µg/ml. Eurycomalongifolia decreased the UGT enzyme activity significantly (p < 0.01), both for in vivo and in vitro study