The Benefits of Flavonoids in Diabetic Retinopathy

Abstract

Diabetic retinopathy (DR), one of the most common complications of diabetes, is the leading cause of legal blindness among adults of working age in developed countries. After 20 years of diabetes, almost all patients suffering from type I diabetes mellitus and about 60% of type II diabetics have DR. Several studies have tried to identify drugs and therapies to treat DR though little attention has been given to flavonoids, one type of polyphenols, which can be found in high levels mainly in fruits and vegetables, but also in other foods such as grains, cocoa, green tea or even in red wine. Flavonoids have anti-inflammatory, antioxidant and antiviral effects. Since it is known that diabetes induces oxidative stress and inflammation in the retina leading to neuronal death in the early stages of the disease, the use of these compounds can prove to be beneficial in the prevention or treatment of DR. In this review, we summarize the molecular and cellular effects of flavonoids in the diabetic retina.

Plants Secondary Metabolites as Blood Glucose-Lowering Molecules

“…Antioxidant power is a preliminary factor for the prediction of antidiabetic activity [ 218 ]. NADPH oxidase inhibitors—such as anthocyanins, xanthine oxidase inhibitors—such as catechin and gallic acid, and SOD mimetics can neutralize free radical generation [ 219 , 220 , 221 , 222 ].…”

Chemical Composition, Antioxidant, and α-Glucosidase-Inhibiting Activity of Aqueous and Hydroethanolic Extracts of Traditional Antidiabetics from Croatian Ethnomedicine

“…Flavonoids are a group of phenolic compounds that have a significant potential to combat the consequences and complications of T2D e.g., by attenuating the progression of diabetic retinopathy. It is widely recognized that many of their observed effects are closely related to their antioxidant properties [31]. TF content of the investigated extracts is presented in Table 4.…”

Optimization of Two Eco-Friendly Extractions of Black Medick (Medicago lupulina L.) Phenols and Their Antioxidant, Cosmeceutical, α-Glucosidase and α-Amylase Inhibitory Properties

“…Their antioxidant and anti-inflammatory activity, as well as the ability to counteract various processes that occur under oxidative stress conditions, enables them to slow down aging, as well as to prevent or combat numerous contemporary degenerative diseases, including diabetes [ 5 ]. In addition, when taken by mouth, food phenolics, such as flavonoids [ 6 ] and phenolic acids [ 7 ], may come into contact and cause inhibition of gastrointestinal enzymes, including α-amylase and α-glucosidase, two enzymes responsible for break-down of starch and oligosaccharides, respectively. Reduction of complex carbohydrates digestion rates leads to better glycemic control and slows down progression of the disease.…”

“…Reduction of complex carbohydrates digestion rates leads to better glycemic control and slows down progression of the disease. Furthermore, a growing body of research suggests that natural phenolics may counteract glucose-induced oxidative stress in diabetic patients, restore the levels of endogenous antioxidants in affected tissue and prevent or even reverse diabetic complications [ 2 ] such as neurological or ocular damage [ 6 ]…”

“…Reduction of complex carbohydrates digestion rates leads to better glycemic control and slows down progression of the disease. Furthermore, a growing body of research suggests that natural phenolics may counteract glucose-induced oxidative stress in diabetic patients, restore the levels of endogenous antioxidants in affected tissue and prevent or even reverse diabetic complications [2] such as neurological or ocular damage [6] Even though plant phenolics are most renowned for their role in health promotion, they are increasingly being used in cosmetic industry [5], where the antioxidant potential and their myriad biological activities render natural phenolics ideal preservatives and functional ingredients in natural cosmetics [8]. As a result, plants rich in flavonoids, phenolic acids, coumestans and other plant phenolics are increasingly being used in so-called cosmeceuticals, the products that share characteristics of pharmaceutical and cosmetic agents [9][10][11].…”