Antioxidant Activity of Cyanidin-3-O-Glucoside and Verbascoside in an in Vitro Model of Diabetic Retinopathy

Abstract

Background: Reactive oxygen species (ROS) accumulation plays a pivotal role in the onset of cell damage induced by hyperglycemia and represents one of the major factors in the pathogenesis of diabetic retinopathy. In this study, we tested the antioxidants cyanidin-3-O-glucoside (C3G) and verbascoside (Verb) in the protection of retinal endothelium against glucose toxicity "in vitro". Methods: Increasing amounts (5-50 µM) of C3G, Verb or the combination of both compounds were tested in Human Retinal Endothelial Cells (HREC) grown with normal glucose (5 mM, NG) or high glucose (25 mM, HG). Results: Reduced cell viability and enhanced ROS levels (evaluated by MTT and H2DCFDA assays, respectively) in HG-stimulated HREC were restored by C3G and Verb in a dose-dependent manner, achieving the maximum protection in the presence of both compounds. Moreover, co-treatment with C3G and Verb worked better than each single molecule alone in the prevention of the disruption of blood-retinal-barrier-like properties by HG in a confluent HREC monolayer, as assessed by trans endothelial electrical resistance (TEER) and Na-Fluorescein permeability assays. Accordingly, C3G and Verb together also better counteracted the HG-induced down-regulation of the tight junction membrane proteins Zonula Occludens-1 and VE-Cadherin evaluated by immunocytochemical and Western blot analyses. Conclusions: In conclusion, our data indicate that C3G and Verb could efficiently protect the retinal endothelium against high glucose damage.

Verbascoside-Rich Plant Extracts in Animal Nutrition

“…Similarly, in human retinal endothelial cells treated with a high dosage of glucose, VB in the cells culture media at 50 µM can decrease the amount of ROS by 25% [31]. Moreover, the antioxidant activity of natural extracts containing VB (485 mg/100 g dry weight) was also dependent on its ability in chelate metal ions [32].…”

Nutraceuticals for Diabetic Retinopathy: Recent Advances and Novel Delivery Systems

“…Cyanidin-3-glucoside (C3G), also called chrysanthemin, is one of the most widely distributed anthocyanins found in nature. Similar to BRAs, C3G showed protective effects in in vivo and in vitro models of DR but gained more attention for its relative stability and easier absorbance [ 106 , 107 , 108 ]. Molecular docking analysis revealed that C3G could combine well with 78-kDa glucose-regulated protein (GRP78), a major endoplasmic reticulum (ER) chaperone protein, hence regulating ER stress [ 105 , 109 ].…”