Pharmacological Evaluation of Gallic Acid, an Active Constituent from a Natural Sources, for the Treatment of Diabetic Retinopathy

Abstract

Objective: Diabetic retinopathy is a serious complication of diabetes and recent findings suggested that gallic acid has PPARα/γ dual agonistic along with antioxidant, antiangiogenic, and anti-inflammatory properties. Therefore, the objective of the present study was ‘‘Pharmacological evaluation of gallic acid for the treatment of diabetic retinopathy’’. Methods: Diabetic retinopathy was induced by the administration of streptozotocin (50mg/kg i.p.) in female Wistar rats. The effect of gallic acid was also assessed at three different doses (5mg/kg, 25mg/kg, 50mg/kg) for 13 weeks. At the end of the study, the animals were euthanized, blood samples were collected, and serum was separated for estimation of various biochemical parameters. Retinal vascular permeability, outer nuclear layer thickness, ganglion layer cell counts, and angiogenesis were measured in the retina. livers tissue homogenate was used to assess oxidative parameters, while the retina was preserved in 10% formalin for histological examination purposes. Results: The study results demonstrated that treatment with gallic acid showed a significant decrease in blood glucose and lipid profiles and the treatment groups dose-dependently. Additionally, treated groups at 25 mg/kg gallic acid, 50 mg/kg gallic acid, and 5 mg/kg saroglitazar showed improvements in LDH, C-reactive protein, and vascular endothelial growth factor levels. Treatment groups also ameliorated retinal vascular leakage, outer nuclear layer thickness, ganglion layer cell counts, and angiogenesis in diabetic rats. Furthermore, gallic acid at 50 mg/kg doses led to improvements in oxidative parameters such as lipid peroxidation, reduced glutathione, and superoxide dismutase levels. Conclusion: This study's findings demonstrated that gallic acid effectively suppressed hyperglycemia, hyperlipidemia, retinal inflammation lower C-reactive protein, Lactate dehydrogenase and VEGF levels, and ameliorate oxidative stress, along with the decrease in retinal vascular permeability, angiogenesis, and reduced outer nuclear layer thickness, and ganglion layer cell counts. Hence, Gallic acid showed its defensive role against streptozotocin-induced diabetic retinopathy in animals. This study reveals that gallic acid has the potential to prevent the progression of retinopathy in diabetic patients.