Determination of antioxidant properties in murraya koenigii and eugenia polyantha leaves / Nor Juwariah Mukhtar

Nowadays, interest in plant-derived food additives has grown, mainly because synthetic antioxidants suffer from several drawbacks. Futhermore, plant extracts have been shown to possess health-promoting properties. In the present studies, water and ethanolic extracts of Murraya koenigii (curry) and Eugenia polyantha (salam) were investigated for their antioxidant activity, total phenolic and total flavonoid content. The antioxidant assay used were P-carotene bleaching assay, 2,2-dipenyl-l-picrylhydrazyl (DPPH) radical scavenging activity assay and Ferric reducing power assay using in vitro spectrophotometric methods. The antioxidant activities of water and ethanol extract for both samples also had been compared to investigate the effects of antioxidant activities using different extraction medium. The extracts of both curry and salam leaves showed high antioxidant activities with up to 97% and 89% respectively. All antioxidants assays showed that standard BHT exhibit higher antioxidant activities followed by salam leaves and curry leaves. Both curry and salam leaves showed high phenolic content in water extracts compared with ethanolic exracts. Total phenolic content was in range of 0.072g to 1.460g GAE in lOOg of sample. For total flavonoid content, both curry and salam leaves showed high flavonoid content in ethanolic extracts than water extracts. A positive correlation was shown between antioxidant activity and total phenolic content. The correlation between total phenolic content with P-carotene bleaching assay, DPPH radical scavenging activity assay and Ferric reducing power assay were R2 =0.475, R2 =0.975, R2 =0.927 respectively However, a negative correlation was shown between antioxidant activities and total flavonoid content. This showed that phenolic compound might contributed to the antioxidant activities in both curry and salam leaves.