Quantitative measurement of bioactive compounds from leaves of syzygium samarangense with antioxidant efficacy

Botanicals have been explored for their multitude of pharmaceutical and therapeutic potential. In this study, crude methanolic extract (MSSL) and organic soluble fractions of Syzygium samarangense leaves were evaluated for antioxidant activity using in vitro and in vivo models. To evaluate the antioxidant activity, total antioxidant capacity, free radical scavenging ability (DPPH) and reducing power, assays were conducted in vitro. Lipid peroxidation and activities of different antioxidant enzymes were measured in vivo. Quantitative phytochemical analyses such as the measurement of total phenolic, flavonoid, flavonol, and proanthocyanide contents were also evaluated. The ethyl acetate fraction (ESSL) showed significant effects in DPPH assay (IC₅₀ = 38.84 ± 0.08 μg/mL) and reducing power assay. The effect of ESSL was found to be concentration-dependent with remarkable antioxidant activity as compared to other tested samples. In addition, administration of the extract/fractions (200 and 400 mg/kg body weight) to male Wistar rats increased the percentage of inhibition of reduced glutathione, superoxide dismutase and catalase significantly (p < 0.05). The level of lipid peroxidation decreased at 400 mg/kg body weight after seven days in hepatotoxic rats. The pharmacological findings of this study clearly indicate that extracts and/or fractions of Syzygium samarangense leave could be a source of natural antioxidants.