Antioxidant effect of silymarin on paraquat-induced human lung adenocarcinoma A549 cell line

Paraquat (PQ) is not only widely used as a potent herbicide but also causes severe fatality to humans around the world due to accidental or intentional ingestion. Silymarin is a well-known phytochemical whose multi-functional effects in humans include anti-oxidant, anti-inflammatory and anti-cancer activities. The efficacy of silymarin in protecting against PQ-induced cytotoxicity is unknown. This study investigated the potential role of silymarin against PQ-induced oxidative stress on human A549 adenocarcinoma cell line. Colorimetric-based viability assay, determination of reactive oxygen species, cell damage assay based on lactate dehydrogense retention, anti-oxidant enzyme assay, Western blot and quantitative reverse transcription-polymerase chain reaction analyses were done. Our data revealed that silymarin could dramatically prevent cell toxicity, and reduce the LDH retention induced by PQ on A549 cell line. Silymarin acted as a potent cytoprotective effector through the effective induction of anti-oxidant related genes, including Nrf2, NQO1 and HO-1, in the presence of PQ. The induction of the Nrf2, HO-1 and NQO1 genes was first evident after 3 h. The data indicate the potential of silymarin in alleviating PQ intoxication.