Mechanisms of the Effects of Polyphenols on Diabetic Nephropathy.

Diabetic nephropathy is a major challenge in medicine. While a variety of mechanisms underlie the onset and progression of diabetic nephropathy, oxidative stress is critical because it promotes inflammation and creates a vicious cycle that induces podocyte injury, extracellular matrix accumulation, glomerulosclerosis, epithelial-mesenchymal transition, tubular atrophy, and proteinuria. There are various treatments for diabetic nephropathy, and each has its own limitations. Although the exact mechanisms by which polyphenols suppress diabetic nephropathy have not been elucidated, they may have antioxidant, anti-inflammatory, antifibrotic, and/or anti-apoptotic effects. They may also suppress endoplasmic reticulum stress and ameliorate mitochondrial dysfunction and dyslipidemia. Dietary polyphenols may be able to prevent the onset and slow the progression of diabetic nephropathy; they include resveratrol, quercetin, isoflavones, catechins, and anthocyanidins and have antioxidant, anti-inflammatory, antifibrotic, and anti-apoptotic effects through multiple molecular targets. Furthermore, they have shown few side effects. However, further research is needed to fully elucidate the molecular mechanisms by which polyphenols exert their effects and to clarify their optimal therapeutic use. In this review, we summarize reports published in the past five years regarding their effects on diabetic nephropathy and provide an overview of the potential of polyphenols.