Chemical components and antioxidant activities of methanol extract of Syzygium polycephalum Miq. stem bark (Myrtaceae)

Abstract

This study aimed to reveal chemical components and screen antioxidant activity of methanolic extract of Syzygium polycephalum stem bark. The chemical components were isolated by using column chromatographic techniques and determined by spectroscopic methods (UV-Vis, FTIR, MS, and NMR) and comparison with literature data, in which the antioxidant activity was performed using 2,2’-diphenyl-1-picrylhydrazyl (DPPH). The present investigation resulted in four compounds involving gallic acid, pinostrobin, 3,4,3’-tri-O-methylellagic acid, and 3,3’-di-O-methylellagic acid. The four compounds were all in the form of phenolic compounds found from the extract whereas 3,4,3’-tri-O-methylellagic acid and 3,3’-di-O-methylellagic acid were ellagic acid derivatives. The methanolic extract, the four compounds, and vitamin C (as positive control) showed antioxidant activity against DPPH with the IC₅₀ value of 99.9; 10.0; 183.2; 72.1; 63.3; and 13.9 µg/mL, respectively. The antioxidant activity of gallic acid was more active than that of vitamin C. The present study confirms that Syzygium polycephalumis rich in phenolic compounds and natural antioxidants.