Evaluation of Nigerian Medicinal Plants Extract on Human P-glycoprotein and Cytochrome P450 Enzyme Induction: Implications for Herb-drug Interaction.

Background: Herbal medicine represents a significant component of disease prevention and therapy in most African countries. Herb-drug interactions (HDI) can arise from the co-administration of herbal and orthodox medicines.
Objective: This study assessed the potential for HDI of V. amygdalina, O. gratissimum, M. oleifera, A. indica, and P. nitida extracts using in vitro assays. Little is known about these medicinal plants' potential for drug interaction despite their extensive use in Nigeria for several disease conditions.
Method: The medicinal plant crude extracts were evaluated for Cytochrome P450 (CYP) enzyme induction using cryopreserved human hepatocytes. Enzyme activity was determined by quantifying probe substrate metabolism and metabolite formation using liquid chromatography-mass spectrometry/mass spectrometry. The extracts were evaluated for the potential to inhibit P-glycoprotein (P-gp) activity using human embryonic kidney membrane vesicles over-expressing human P-gp. The herbal extracts in vivo drug interaction potential was predicted based on the USFDA drug interaction guidance.
Result: O. gratissimum and P. nitida methanol extracts induced CYP1A2 enzyme activity by greater than 3-fold. P. nitida methanol extracts showed over 2-fold induction of CYP1A2 mRNA expression. O. gratissimum methanol extract induced CYP2B6 mRNA expression over 2-fold. P. nitida and A. indica methanol extracts showed potent inhibition of P-gp activity (IC ₅₀ : 3.8 and 5.4 μg/mL), respectively, while V. amygdalina and M. oleifera methanol extracts showed moderate P-gp inhibition (IC50: 12.1 and 37.2 μg/mL, respectively).
Conclusion: Our studies suggested that the medicinal plants' extracts can modulate CYP enzymes and P-gp activity with the potential to cause herb-drug interaction in vivo.
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