Antioxidative mechanisms of sea buckthorn fruit extract in mouse embryonic fibroblast cells

This study was conducted to define the antioxidant properties and cytoprotective mechanisms of sea buckthorn fruit extract (SFE) against cellular oxidative stress in mouse embryonic fibroblast (MEF) cells. Cell viability of MEF cells damaged by H₂O₂ was significantly increased by addition of SFE in a concentration dependent manner. Cytoprotective effect of SFE against oxidative damage was observed to be co-related with regulation of cell cycle progression. Induction of cell cycle arrest in G₂/ M checkpoint was mediated by oxidative stress, but significantly reduced by treatment of MEF cells with SFE. Analysis of key regulatory proteins involved in G₂/M arrest showed that SFE treatment leads to down-regulation of both phosphorylated Chk1 and cyclin B, which play important roles in cell cycle arrest of oxidatively damaged cells. Effect of SFE on apoptosis was evaluated by morphological and flow cytometric analysis. Apoptotic cell accumulation occurred by H₂O₂ treatment was decreased by co-treatment of MEF cells with SFE. Early apoptotic process involved in DNA fragmentation and condensation was also inhibited by additional treatment with SFE. Overall results suggest that cytoprotective effect of SFE is mediated by effective radical scavenging activity as well as altered cell cycle regulation which prevent apoptotic cell death induced by cellular oxidative stress.