Abstract
Morinda citrifolia Linn. (Rubiaceae), common name noni, has been used as a herbal medicine for over 2000 years. The consumption of noni, and especially the fruit, stresses the importance, urgency, and possibility of the examination of drug interaction when concomitantly administered with a drug. The objectives of this study were to determine the effects of noni juice (NJ) on aminopyrine N-demethylase (APND), uridine diphosphoglucuronosyl-transferase (UGT), and cytosolic glutathione S-transferase (GST) drug metabolizing enzymes and the molecular mechanism elucidation of NJ on APND using different inhibitors and stimulators. The in vitro results for APND showed that different concentrations of NJ significantly increased the activity in isolated hepatocytes at 1.0 ng/mL, 10 ng/mL, 10 mu g/mL, 20 mu g/mL, 50 mu g/mL, and 100 mu g/mL. The ex vivo results demonstrated that NJ (210 mg/kg) produced a statistically significant increase in APND activity following I day of NJ treatment. The results for UGT and GST showed a decrease in the activity of UGT at a dose of 21 mg/kg following 1 day of treatment, and at 2.1 and 21 mg/kg following 14 days of treatment. GST enzyme demonstrated an increase in activity by 100% for all doses following 1 day of treatment. Molecular mechanism elucidation of the ex vivo effect of NJ on phase I APND showed that KT5720 significantly reduced the activity as compared to control. A change in activity of APND, UGT, and GST following 1 day and 14 days of treatment suggests that all three metabolic pathways may play a role in herb-drug interaction by modulation of metabolic enzymes.