Inhibitory Effects of , , , and Extracts and Constituents on Human Liver Glucuronidation Activity.

BACKGROUND

, , and are commonly consumed as herbal medicines. However their effects on human liver glucuronidation activity are not yet evaluated.

OBJECTIVE

In this study, we evaluate the inhibitory Effects of Andrographis paniculata, Gynura procumbens, Ficus deltoidea and Curcuma xanthorrhiza extracts and their constituents on human liver glucuronidation activity.

MATERIALS AND METHODS

Herbal extracts (aqueous, methanolic and ethanolic extracts) and their constituents were incubated with human liver microsomes with the addition of UDPGA to initiate the reaction. Working concentrations of herbal extracts and their constituents ranged from 10 μg/mL to 1000 μg/mL and 10 μM to 300 μM respectively. IC50 was determined by monitoring the decrement of glucuronidation activity with the increment of herbal extracts or phytochemical constituent's concentrations.

RESULTS

All herbal extracts inhibited human liver glucuronidation activity in range of 34.69 μg/mL to 398.10 μg/mL whereas for the constituents, only xanthorrhizol and curcumin (constituents of ) inhibited human liver glucuronidation activity with IC50 of 538.50 and 32.26 μM respectively.

CONCLUSION

In the present study, we have proved the capabilities of , , and to interfere with glucuronidation process in human liver microsomes.

SUMMARY

This study documented the capabilities of , , and to inhibit human liver glucuronidation activity which may affect the metabolism of therapeutic drugs or hazardous toxicants that follow the same glucuronidation pathway. UGT: Uridine 5'-diphospho-glucuronosyltransferase; 4-MU: 4-methylumbelliferone; IC50: Half Maximal Inhibitory Concentration; Km: Michaelis constant; Vmax: Maximum velocity.