Antioxidant activity, total phenolics and total flavonoids of Syzygium polyanthum (Wight) Walp leaves

Methanolic extract of Syzygium polyanthum leaves showed mild antioxidant activity with IC50 values of 90.85 μg/ml compared to the standard quercetin (24.09 μg/ml) on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. Nevertheless, the total phenolics was analysed via Folin-Ciocalteau method in which 11125 mg gallic equivalent (GAE) and 312.52 mg caffeic acid equivalent (CAE)/100 g dry leaves were obtained. Analyses by HPLC and LC-MS confirmed the presence of gallic acid and caffeic acid as the major phenolic acids in the methanolic Syzygium polyanthum leaves extract. The total flavonoids analysis based on Down Method and HPLC suggested only a minute percentage of flavonoids in the methanolic extract.