Cyanidin-3-glucoside from black rice prevents renal dysfunction and renal fibrosis in streptozotocin-diabetic rats

Hyperglycemia, increased inflammation, and mitochondrial dysfunction in diabetes may eventually cause kidney damage. Black rice cyanidin-3-glucoside has anti-hyperglycemic and anti-osteoporosis effects. Whether it has preventive effects on renal dysfunction in diabetes has not been reported. In this study, a rat model of diabetic nephropathy was established, and cyanidin-3-glucoside was administered for 56 days, lisinopril was administered as the positive control. The research found that black rice cyanidin-3-glucoside supplementation decreased glucose, prevented insulin resistance, repaired kidney function of diabetic rats, prevented renal interstitial fibrosis, glomerulosclerosis, and oxidative stress of diabetic rats. The inflammatory cytokines were significantly reduced in cyanidin-3-glucoside treated group. The renal Nrf2 mRNA level was evaluated, renal TNF-alpha mRNA, and NF-kappa B mRNA expression levels was decreased in cyanidin-3-glucoside treated group. Immunohistochemical results showed that cyanidin-3-glucoside inhibited transforming growth factor-beta 1 (TGF beta 1), phosphorylated Smad2 (p-Smad2), phosphorylated Smad3 (p-Smad3), type IV collagen, fibronetin, and laminin expression in the kidney of diabetic rats. Our results indicate cyanidin-3-glucoside can protect against diabetic nephropathy in rats; it is mainly attributed to its anti-insulin resistance, anti-oxidative stress, antiinflammation, as well as inhibit TGF-beta 1/p-Smads expression and extracellular matrix (ECM) aggregation.