Evaluation of Antioxidant and Hypoglycemic Properties of Citrus Peel Extracts and Their Implications for Diabetes Management

Diabetes mellitus is a chronic metabolic disorder characterized by persistently elevated blood glucose levels, resulting mainly from impaired insulin production or action. This investigation aimed at examining the antioxidant and hypoglycaemic properties of citrus peel extracts on the management of diabetes. The flavedo and albedo of three cultivars, Long Co Co, Thanh Kieu, and Da Xanh growing in Vietnam were extracted into Pomelo peel extracts (PPE) and evaluated in terms of their main bioactive compounds and functional characteristics. The extracts were analyzed on the basis of their total flavonoid content (TFC), total phenolic content (TPC), vitamin C, and polymethoxylated flavones (PMFs), which are prime indicators of the antioxidant activity. Among the three cultivars, Thanh Kieu albedo PPE exhibited the highest TFC, Da Xanh albedo PPE showed moderate TFC, and Long Co Co albedo PPE had the lowest TFC. The vitamin C content in Thanh Kieu flavedo PPE was the highest. Acute toxicity analysis indicated that the flavedo PPE was toxic at very high doses, and the albedo PPE of all cultivars was found to be safe and non-toxic. The hypoglycemic effect of albedo PPE was significant, with effects comparable to standard treatment. The performance of Thanh Kieu albedo PPE was best with the highest flavonoid (75.5 ± 2.2 mg QE/g), which is comparable to Glucophage. The observed antioxidant and hypoglycemic effects may be attributed to the bioactive compounds present in the extracts, such as flavonoids, phenolics, vitamin C, PMFs, and dietary fibers.