Antioxidant capacities of Amaranthus tristis and Alternanthera sessilis: A comparative study

The aim of the present study was to compare the phytochemical and radical scavenging activities in the stem and leaf fractions of two species in Amaranthaceae family Amaranthus tristis and Alternanthera sessilis. Total flavonoids and phenolics were estimated using aluminium chloride and Folin-Ciocalteau methods, respectively; radical scavenging activities of the extracts were determined by 2, 2-diphenyl-1-picryl hydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assay. Our results showed that A. sessilis had higher levels of flavonoids (70.42 mg/100 g) and phenolics (103.75 mg/100 g), when compared with A. tristis that had relatively lower levels of flavonoids (62.87 mg/100 g) and phenolics (96.89 mg/100 g) in leaf fractions. The stem and leaf fractions of A. sessilis showed more DPPH and FRAP values indicating the higher radical scavenging activity of the extract, when compared to A. tristis. It was also found that the flavonoids and phenolics content are directly proportional to the radical scavenging activities of both vegetables. The results concluded that A. sessilis have relatively more phytochemicals and radical scavenging activities and it also reveals that the leaf fraction has more flavonoid and phenolic content than the stem fractions in both vegetables. It is clear that both plants have definitely more antioxidant properties making it an ideal dietary antioxidant supplement.   Key words: Phytochemicals, antioxidants, total flavonoids, total phenolics, radical scavenging activity.