Role of oxidative stress in diabetic retinopathy and the beneficial effects of flavonoids.

Diabetic retinopathy (DR) is one of the leading causes of decreased vision and blindness in developed countries. Diabetes-induced metabolic disorder is believed to increase oxidative stress in the retina. This results in deleterious changes through dysregulation of cellular physiology that damages both neuronal and vascular cells. Here in this review, we first highlight the evidence of potential metabolic sources and pathways which increase oxidative stress that contributes to retinal pathology in diabetes. As oxidative stress is a central factor in the pathophysiology of DR, antioxidants therapy would be beneficial towards preventing the retinal damage. A number of experimental studies by us and others showed that dietary flavonoids cause reduction in increased oxidative stress and other beneficial effects in diabetic retina. We then discuss the potential beneficial effects of the six major flavonoid families, such as flavonones, flavanols, flavonols, isoflavones, flavones and anthocyanins, which have been studied to improve retinal damage. Flanonoids, being known antioxidants, may ameliorate the retinal degenerative factors including apoptosis, inflammation and neurodegeneration in the diabetic retina. Therefore, intake of potential dietary flavonoids would limit oxidative stress and thereby prevent the retinal damage, and subsequently the development of DR.