Comparative study of antioxidant activity and total phenolic content of stem bark and leaves from Murraya koenigii species

Natural products with medicinal value are gaining popularity because they have fewer side effects than synthetic drugs. Hence, this study aims to investigate the antioxidant potential and its total phenolic content in the leaves and stem bark of Murraya Koenigii species, which were collected from Taman Herba UiTM Jengka Pahang. The goal is to assess antioxidant potential using 2,2-diphenyl-1-picrylhydrazyl (DPPH) through dot blot assay and radical scavenging assay. The total phenolic content (TPC) of leaves and stems of M. koenigii was measured using the Folin-Ciocalteu method. The crude extracts from the stem bark and leaves of M. koenigii were prepared through consecutive maceration using hexane, ethyl acetate, and methanol. The results revealed that the ethyl acetate extract from stem bark and the methanol extract of leaves had promising antioxidant activity, with IC50 values of 77.67 μg/mL and 68.84 μg/mL, respectively. Meanwhile, the dot blot assay analysis indicated that hexane and methanol extracts from the leaves exhibited antioxidant activity at the lowest concentration of 0.048 mg/mL. The methanol extract from stem bark revealed its antioxidant properties through a dot blot assay at a concentration of 0.39 mg/mL. The highest total phenolic content (TPC) values belonged to the methanol extract of stem bark and leaves, with values of 114.25 mg GAE/g sample and 153.25 mg GAE/g sample, respectively. Therefore, the methanol extract from the leaves of M. koenigii is known to be the most promising source of the antioxidant agent, with a high TPC value compared to other extracts. This research's findings are applicable to the medical and pharmaceutical industries as they provide the fundamental scientific data essential for developing new natural drug sources.