In vitro Effects of Four Native Brazilian Medicinal Plants in CYP3A4 mRNA Gene Expression, Glutathione Levels, and P-Glycoprotein Activity

Abstract

Erythrina mulungu Benth. (Fabaceae), Cordia verbenacea A. DC. (Boraginaceae), Solanum paniculatum L. (Solanaceae) and Lippia sidoides Cham. (Verbenaceae) are medicinal plant species native to Brazil shortlisted by the Brazilian National Health System for future clinical use. However, nothing is known about their effects in metabolic and transporter proteins, which could potentially lead to herb-drug interactions (HDI). In this work, we assess non-toxic concentrations (100 μg/mL) of the plant infusions for their in vitro ability to modulate CYP3A4 mRNA gene expression and intracellular glutathione levels in HepG2 cells, as well as P-glycoprotein (P-gp) activity in vincristine-resistant Caco-2 cells (Caco-2 VCR). Their mechanisms of action were further studied by measuring the activation of human pregnane X receptor (hPXR) in transiently co-transfected HeLa cells and the inhibition of γ-glutamyl transferase (GGT) in HepG2 cells. Our results show that P-gp activity was not affected in any case and that only Solanum paniculatum was able to significantly change CYP3A4 mRNA gene expression (twofold decrease, p < 0.05), this being correlated with an antagonist effect upon hPXR (EC50 = 0.38 mg/mL). Total intracellular glutathione levels were significantly depleted by exposure to Solanum paniculatum (-44%, p < 0.001), Lippia sidoides (-12%, p < 0.05) and Cordia verbenacea (-47%, p < 0.001). The latter plant extract was able to decrease GGT activity (-48%, p < 0.01). In conclusion, this preclinical study shows that the administration of some of these herbal medicines may be able to cause disturbances to metabolic mechanisms in vitro. Although Erythrina mulungu appears safe in our tests, active pharmacovigilance is recommended for the other three species, especially in the case of Solanum paniculatum.

Effects of Standardized Medicinal Plant Extracts on Drug Metabolism Mediated by CYP3A4 and CYP2D6 Enzymes

“…Among the CYP enzymes, CYP3A4 is the most abundant in the body, with high expression in the liver and intestine, particularly in the jejunum and ileum. , CYP3A4 enzyme metabolizes about half of the available drugs, and it is modulated by several compounds, such as ketoconazole, verapamil, rifampicin, and clarithromycin. , The second major drug-metabolizing enzyme is CYP2D6, which catalyzes the metabolism of approximately one-third of the available drugs . The inhibition of this isoenzyme may lead to potential adverse interactions through the rapid increase of drug plasma levels leading to drug-induced toxicity …”

In vitro effects of European and Latin-American medicinal plants in CYP3A4 gene expression, glutathione levels, and P-glycoprotein activity

“…This resulted in an increased P-gp activity of Caco-2 cells cultured with vincristine compared to normal Caco-2, which made the conduction of our preclinical study possible. Despite this, the IC 50 of verapamil–a reference for P-gp inhibition–in normal Caco-2 cells is not significantly different than in overexpressing Caco-2 cells after vincristine treatment ( Mazzari et al, 2016 ).…”

“…Their medicinal uses and chemical composition are scientifically backed up (Tables 1, 2) but there is scarce information on their influence on drug metabolism. Thus, a potential risk for herbal-drug interaction for some of these herbal drugs exist as reported in our previous works (Mazzari and Prieto, 2014;Mazzari et al, 2016). Therefore, this study aims to contribute new pre-clinical data on this matter by investigating the in vitro effects of these European and Latin-American medicinal plants on CYP3A4 mRNA gene expression, activation of the human pregnane X receptor (hPXR), intracellular glutathione levels, Gammaglutamyl transferase (GGT), and P-glycoprotein (P-gp) activity.…”

“…Latin American countries possess an enormous part of the world’s biodiversity, with numerous plant species containing medicinal properties ( Mazzari et al, 2016 ). Brazil can be highlighted with around 55,000 species ( Savi et al, 2019 ) and the public policies for introducing Herbal Medicines and other Complementary Practices in the public health system (SUS—Unified Health System), such as National Policy for Complementary and Integrative Practices (PNPIC) and National Policy for Medicinal Plants and Herbal Medicines (PNPMF), both launched in 2006 ( BRASIL, 2006a ; BRASIL, 2006b ).…”