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

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.
Competing Interests: DR and GL are serving as Editorial Board members of this journal. We declare that DR and GL had no involvement in the peer review of this article and had no access to information regarding its peer review. Full responsibility for the editorial process for this article was delegated to GP. DR is a full-time employee of Fidia Pharmaceuticals, a pharmaceutical company that commercializes a food supplement containing C3G and verbascoside.
(© 2022 The Author(s). Published by IMR Press.)