Ginsenoside Rb1 alleviates diabetic kidney podocyte injury by inhibiting aldose reductase activity

Panax notoginseng, a traditional Chinese medicine, exerts beneficial effect on diabetic kidney disease (DKD), but its mechanism is not well clarified. In this study we investigated the effects of ginsenoside Rb1 (Rb1), the main active ingredients of Panax notoginseng, in alleviating podocyte injury in diabetic nephropathy and the underlying mechanisms. In cultured mouse podocyte cells, Rb1 (10 μM) significantly inhibited high glucose-induced cell apoptosis and mitochondrial injury. Furthermore, Rb1 treatment reversed high glucose-induced increases in Cyto c, Caspase 9 and mitochondrial regulatory protein NOX4, but did not affect the upregulated expression of aldose reductase (AR). Molecular docking analysis revealed that Rb1 could combine with AR and inhibited its activity. We compared the effects of Rb1 with eparestat, a known aldose reductase inhibitor, in high glucose-treated podocytes, and found that both alleviated high glucose-induced cell apoptosis and mitochondrial damage, and Rb1 was more effective in inhibiting apoptosis. In AR-overexpressing podocytes, Rb1 (10 μM) inhibited AR-mediated ROS overproduction and protected against high glucose-induced mitochondrial injury. In streptozotocin-induced DKD mice, administration of Rb1 (40 mg·kg^-1·d^-1, ig, for 7 weeks) significantly mitigated diabetic-induced glomerular injuries, such as glomerular hypertrophy and mesangial matrix expansion, and reduced the expression of apoptotic proteins. Collectively, Rb1 combines with AR to alleviate high glucose-induced podocyte apoptosis and mitochondrial damage, and effectively mitigates the progression of diabetic kidney disease.