# Investigation of the regulatory effects of tea polyphenols on CYP450s in HepG2 cells

## TL;DR

This study shows that tea polyphenols can regulate CYP450 enzymes in liver cells, which may affect how drugs are metabolized in the body.

## Contribution

The study provides new evidence on how tea polyphenols modulate CYP450 enzymes in HepG2 cells.

## Key findings

- Tea polyphenol extracts significantly regulate CYP450 mRNA and protein expression.
- Enzyme inhibition was more common than induction, with major contributions from EGCG, EGC, and ECG.
- Tea polyphenols may interact with medications through metabolic pathways.

## Abstract

Tea, one of the world's three major beverages, exhibits antioxidant, antitumour, and cardiovascular benefits, primarily due to its polyphenolic components. However, the roles of tea polyphenols on the modulation of cytochrome P450 enzymes (CYP450s) are not well documented. Therefore, this study investigates the regulatory effects of tea polyphenols on CYP450s in HepG2 cells.

High-performance liquid chromatography (HPLC) was used to analyse the compositions of tea polyphenol extracts from Longjing green tea (unfermented), Tieguanyin oolong tea (semifermented) and Dianhong black tea (fully fermented). HepG2 cells were treated with these extracts and their major polyphenolic constituents (EGCG, EGC, ECG, TF, TF-3-G, and TF-3′-G), and the mRNA and protein expression levels of CYP3A4, CYP2E1, CYP2C9 and CYP1A2 were measured using real-time RT–PCR and Western blotting.

Significant regulation of CYP450 mRNA and protein expression by the three tea polyphenol extracts was observed, and enzyme inhibition was more prevalent than induction, with large contributions from the major monomers, including EGCG, EGC, and ECG. These findings indicate that interactions based on metabolism might occur when tea polyphenols are combined with medications.

This study provides evidence that tea polyphenols significantly affect CYP450 enzyme expression, offering insights into the potential interactions between tea consumption and drug metabolism.