Abstract

The present study was conducted to evaluate the phenolics, antioxidant and antimicrobial activities of leaf and seed extracts from an edible herb namely Amaranthus viridis L. The extract yields of active components, produced using pure and aqueous methanol, from the leaves and seeds ranged from 5.4 to 6.0 and 2.4 to 3.7%, respectively. The extracts contained appreciable levels of total phenolic contents (1.03 to 3.64 GAE, g/100 g) and total flavonoid contents (18.4 – 5.42 QE, g/100 g) and also exhibited good 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity as revealed by IC₅₀ (14.25 - 83.43 µg/ml). Besides, the tested extracts showed considerable antimicrobial activity against selected bacterial and fungal strains with minimum inhibitory concentrations (MIC) ranging from 179-645 µg/ml. Of the parts tested, the seed extracts exhibited superior antioxidant and antimicrobial activity. It was concluded that A. viridis leaf and seed can be explored as a potential source for isolation of antioxidant and antimicrobial agents for uses in functional food and pharmaceuticals.

Key words: Amaranthus viridis, phytochemical constituents, minimum inhibitory concentrations (MIC), total phenolics, total flavonoids, 1,1-diphenyl-2-picrylhydrazyl (DPPH), radical scavengers.