Evaluation of the Effects of Instant Black Tea on the Gene Expression of PON1, as well as Its Paraoxonase and Lactonase Enzyme Activities, in HepG2 Cells

Objective: Instant black tea (IBT) is a water-soluble tea that has a number of properties, including antioxidant, antibacterial, antitoxic, antiviral, antimutagenic, anticancer, and anti-inflammatory effects, among others. The aim of this study was to investigate the effects of IBT on paraoxonase 1 (PON1) gene expression and its paraoxonase and lactonase activities, in a hepatoma cell line (HepG2).Material and Methods: PON1 gene expression was determined by RT-PCR. Paraoxonase and lactonase activities were examined using spectrophotometry. These measurements were performed after 24 and 48 hours of treatment in HepG2 cells. Results: Compared to the negative control, 100 μg/mL IBT treatment suppressed PON1 gene expression at 24 hours; 50 μg/mL treatment at 24 hours and 100 μg/mL treatment at 48 hours increased paraoxonase activities; and finally 50 and 100 μg/mL treatments at 48 hours decreased lactonase activities, all of which were statistically significant (p < .05).Conclusion: IBT can modulate PON1 expression and related enzyme activities in hepatocytes, but detailed in vivo studies are required to confirm these findings and elucidate their biological effects.