Transcript-Level Modulation of Drug-Metabolizing Enzymes by Echinacea, Salvia,and Thymus in Adult Male Rats: Implications for Herb-Drug Interactions

Abstract

BACKGROUND: Herb-Drug Interactions (HDIs) are a major clinical concern, as they may alter drug efficacy or cause toxicity. This study evaluated the potential HDIs of Echinacea purpurea, Thymus vulgaris, and Salvia officinalis by assessing their effects on Drug-Metabolizing Enzyme (DME) gene expression in rats. METHODS: Rats (n = 10/group) received Echinacea purpurea (50 mg/kg), Salvia officinalis (400 mg/kg), Thymus vulgaris (500 mg/kg), or vehicle for 15 days. Hepatic transcripts of Cyp3a1, Cyp2d1, Ephx1, Ugt1a1, Ces1, and Nqo1 were quantified by qPCR. Serum and hepatic biomarkers, oxidative stress indices, and histology of liver and kidney were also assessed. RESULTS: All extracts increased the mRNA levels of drug-metabolizing enzymes (2-8-fold) as measured by qPCR; protein expression and enzymatic activities were not assessed. Thymus vulgaris increased serum proteins and hepatic NO and GSH, while ALT rose in the Salvia officinalis and Thymus vulgaris groups. MDA was elevated in all groups. Histology showed mild hepatocellular vacuolation with Echinacea purpurea and minor hemorrhage with Thymus vulgaris. All extracts slightly increased serum creatinine with minimal renal lesions. DISCUSSION: These findings suggest that the three herbs may modulate DME expression at the transcript level and promote mild oxidative histopathological changes after subchronic exposure. Since only mRNA was measured, functional consequences for protein abundance and enzyme activity remain to be confirmed. CONCLUSION: Echinacea, Salvia, and Thymus may contribute to HDIs by altering DME gene expression and inducing early hepatic and renal stress in rats. Further studies at the protein, enzymatic, and pharmacokinetic levels are required to determine whether these findings have clinical relevance.