Djulis ( Chenopodiun formosaneum ) and its bioactive compounds protect against oxidative stress in human HepG2 cells

•Betanin, rutin, kaempferol and another twenty compounds are present in Djulis.•WECF demonstrates a cytoprotection in t-BHP-induced HepG2 cells.•The levels of GSH, MDA and ROS in t-BHP-induced cells are affected by WECF.•The anti-apoptosis in t-BHP-induced cells by WECF is verified.•WECF prevents oxidative stress due to antioxidant and anti-apoptosis of cells.