Background:
Strobilanthes crispus (L.) Bremek (Acanthaceae) leaves are used traditionally
in Malaysia, Thailand, and Indonesia for anti-diabetic, anti-lytic, diuretic, and laxative purposes.
Herb-drug interactions may potentiate or antagonize the absorption and metabolism of drugs which
may result in potential toxicity. The aim of the present study was to investigate the effect of juice,
hot aqueous, cold aqueous and methanol extracts of S. crispus leaves on phase I cytochrome 3A4
(CYP3A4) and Cytochrome 2E1 (CYP2E1) and phase II human liver enzyme UDP-Glucuronosyl
Transferase (UGT).
Methods:
The herb-drug interactions of the leaf extracts and juice were determined by specific enzyme
activity of CYP isoforms with specific probe substrate using spectrophotometry. CYP3A4 activity
was measured for aminopyrine specific metabolite (formaldehyde) at 415 nm. CYP2E1 activity
was determined using p-nitrophenol specific metabolite (p-nitrocatechol) at 535 nm. UGT activity
was quantified through the consumption of p-nitrophenol by UGT at 405 nm.
Results:
All the S. crispus preparations showed significant inhibition of CYP3A4 activity. Only the
methanolic extract showed a significant inhibition in CYP2E1. All the S. crispus extracts showed a
significant effect on UGT activation at the higher concentration (1000 ng/ml). Only the cold aqueous
extract and the juice showed UGT inhibition at lower concentration (1 ng/ml).
Conclusion:
S. crispus preparations showed in-vitro drug-herb interaction effects on human liver
microsomes. Therefore, there is a possibility of drug-herb interaction could occur with S. crispus
leaves through its effect on CYP3A4. Inhibition of the herb extracts on CYP2E1 could show anticarcinogenesis
effects. The potency of drugs that metabolized via UGT pathway may be affected
when co-administered with S. crispus leaf preparations.
Human Liver Microsomal Metabolism of (+)-Discodermolide
