Antidiabetic and antioxidant activities of methanol extract of Syzygium operculatum (Roxb.) Niedz. bark

Objective: To evaluate the antidiabetic and antioxidant effects of the methanol extract of Syzygium operculatum bark (MSOB) using in vivo and in vitro models. Methods: Antidiabetic activity was assessed by using alloxan induced (120 mg/kg body weight) diabetic mice. The plant extract (200 mg/kg and 400 mg/kg body weight) was administrated i.p. to diabetic mice in comparison with standard metformin hydrochloride (150 mg/kg body weight). The antioxidant activity of the extract was evaluated by using a range of in vitro assays and results were compared to standards. Results: The extract MSOB 200 mg/kg and 400 mg/kg reduced the blood glucose level 44.05% and 55.53% respectively where the standard drug metformin reduced 69.42% in dose of 150 mg/kg body weight. The extract MSOB showed significant 1,1-diphenyl-2-picrylhydrazyl scavenging activity, total phenol content, total flavonoid content and reducing power capacity compared to standards. The IC50 values were found 300.34 μg/mL in 1,1-diphenyl- 2-picrylhydrazyl radical scavenging assay where 40.31 μg/mL for ascorbic acid. The total phenol and flavonoid contents were 197.5 and 267.5 mg of gallic acid equivalent per gram, respectively. Conclusions: The present study indicates that the extract of Syzygium operculatum bark is the potential sources of natural antioxidant and possesses significant antidiabetic activities