Effects of the extracts and derived fractions of four medicinal plants on hepatic microsomal enzymes: an in-vitro study

Background: The use of medicinal plants for treatment of diverse ailments has continued to increase worldwide,
especially in developing countries. The concurrent use of herbal medicines and conventional drugs is common.
Herb-drug interaction through the inhibition/induction of cytochrome (CYP) P450 metabolizing enzymes could
result in pharmacotoxicity/therapeutic failure.

Objective: This study investigated the extracts and fractions of four medicinal plants (Crinum glaucum, Baphia
nitida, Byrsocarpus coccineus, and Sanseviera liberica) for possible effects on hepatic microsomal enzymes in-
vitro.

Methods: The benzyloxy-4-[trifluoromethyl]-coumarin O-debenzyloxylase (BFCOD; CYP3A4) and
benzyloxyresorufin O-debenzylase (BROD; CYP2B1/2) assays were used.

Results: The ethyl acetate:methanol and ethanol:water extracts of the plants demonstrated significant (p < 0.05)
inhibitory effect on CYP activity, pronouncedly at the highest concentration (1 mg/ml) in the BROD assay. The
aqueous extracts and fractions of all the plants did not significantly affect CYP activity in both assays. The same
trend of observation was recorded in the BFCOD assay except that the ethyl acetate:methanol extract of C.
glaucum did not significantly affect CYP activity. The ethyl acetate:methanol extract of B. nitida and B. coccineus
elicited significant stimulatory effect at 0.01 and 0.1 mg/ml in the BROD assay. The hexane and n-butanol
fractions of the extracts showed varying tendency to cause stimulation of CYP activity at lower doses and
inhibition at the highest dose.

Conclusion: Findings suggest that the aqueous extracts/fractions of the plants investigated have little or no
tendency to significantly affect CYP activity. Other organic solvent extracts/fractions possess the ability to inhibit
CYP activity, especially at high doses