Investigation of isoflavone constituents from tuber of Apios americana Medik and its protective effect against oxidative damage on RIN-m5F cells

•Eleven main compounds were purified, identified and quantified from AI-3.•HMG has the strongest protective effect against H2O2-induced RIN-m5F cells injury.•HMG protect β-cell from H2O2 damage through Keap1-Nrf2 -ARE signaling pathway.•HMG up-regulated the expression of HOX-1, GST, NQO1, SQSTM, HO-1, TrxR1. In our previous study, AI-3, a mixture of isoflavones, was obtained from Apios Americana Medik tuber and showed strong protective ability on oxidative damaged RIN-m5F cells. This study aimed to identify the main compounds of AI-3 and elucidate their activities and underlying mechanism. In results, eleven compounds were purified from AI-3. Among them, Compound 8 (2′-Hydroxy, 5-methoxy genistein-7-O-glucoside, HMG) was the most effective compound against H2O2-induced injury in RIN-m5F cells (stronger than positive control α-LA). Further RNA-seq analysis found that compared with H2O2 group, 388 differentially expressed genes (DEGs) were identified in HMG group. The enrichment analyses revealed fluid shear stress and atherosclerosis pathway and hepatocellular carcinoma pathway enriched the most DEGs, in which HOX-1, GST, NQO1, SQSTM, TrxR1 were significantly up-regulated. The finding indicated Keap1-Nrf2-ARE signaling pathway may play essential role in the protective effect of HMG on oxidative damaged RIN-m5F cells.