Comparative Evaluation of Antioxidant Properties of Methanol Extracts of Allium cepa bulb, Allium cepa bulb peels and Allium fistulosum.

Abstract

Medicinal plants have protective effects against many physiological diseases because of their phytochemical components which are better antioxidants. This study was aimed at comparing the in vitro antioxidant activity, phenolic and flavonoid content of the methanol extracts of Allium cepa bulb, Allium cepa bulb peel and Allium fistulosum. The antioxidant activity was determined by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, ferric reducing antioxidant power (FRAP), iron chelating activity and molybdate ion reduction assays. The total flavonoid and total phenolic content (TPC) were carried out using aluminium chloride and Folin-Ciocalteu assay respectively. The results showed that A. cepa bulb peel has the highest phenolic content and the antioxidant activity while the A. fistulosum showed the least. Furthermore, the total flavonoid content and metal iron chelating activity was highest in A. cepa bulb, while lowest values were obtained in A. fistulosum and A. cepa bulb peel respectively. The results suggest that the A. cepa bulb peel, A. cepa bulb and A. fistulosum extracts can be used as sources of natural antioxidants. However, A. cepa bulb peel may be the most potent.