0217 : Antioxidant and protective effects of a pu-erh tea extract (camellia sinensis) on primary cultured rat cells

Abstract

Oxidative stress is recognized to be implicated in the pathogenesis of cardiovascular and non-alcoholic fatty liver diseases. It is well know that tea is a rich source of phenolic compounds known for their antioxidant activity. Consequently, the antioxidant and protective effects of phenolic compounds from a pu-erh tea extract (PTE) was evaluated on primary culture of rat hepatocytes. PTE was quantified for its composition in catechins and polyphenol content by HPLC analysis. The antioxidant capacity of tea products was determined using TAC and DPPH assay methods. Then, antioxidant and hepatoprotective effects were determined by pretreating hepatocytes during 4h with various concentrations of PTE (25, 50 and 100μg/ml), epigallocatechin-3-gallate (EGCG) as major catechin of PTE (12μM corresponding to 100μg/ml PTE) and N-acetylcystein (NAC) (0.1 and 1mM) as an antioxidant reference. Then, cells were stressed for 1h with 150μM tert-Butyl hydroperoxide (TBHP). Viability was determined by real time cellular impedance and MTT assays. Oxidative stress was measured by CellRox, MitoSox and TMRE stainings and evaluated by fluorescence microscopy on an ArrayScanXTI high Content Analysis Reader (Cellomics Inc.). We found that TBHP induced oxidative stress (+1.5 fold increase vs control) was prevented by PTE pretreatment (+1.07 fold increase vs ctrl) and EGCG (+1.1 fold increase vs ctrl). We also demonstrated that PTE pretreatment protected rat hepatocytes (–28% mortality relative to TBHP) against TBHP induced mortality (+23% mortality relative to ctrl). However, EGCG did not prevented death in the same proportion than PTE (–9% mortality relative to TBHP). In this study, we reported that PTE pre-exposure prevented oxidative stress and mortality induced by TBHP. Moreover, we reported here that PTE has higher antioxidative and protective effects than EGCG alone, well known for its antioxidant effects, which means that EGCG may act in synergy with other PTE components.