Antibacterial activity assessment of petroleum ether and methanolic extracts of Achyranthes aspera Linn (Amaranthaceae)

Achyranthus aspera is a common weed and known for various medicinal properties. The aim of the present study was to evaluate the antibacterial activities of different concentrations of methanolic and petroleum-ether leaf extracts of A. aspera against three gram-positive bacteria (Micrococcus luteus, Bacillus subtilis, Streptococcus mitis) and six gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia, Salmonella typhi, Salmonella paratyphi A (MTCC-3220), Shigella flexneri). The phytochemical screening of the leaf extract of the herb indicated the presence of flavonoides, tannins, saponins, polyphenolic compounds, alkaloids and glycosides. The methanolic extract at the highest concentration of 10 mg/ml showed prominent antibacterial activity in two gram-negative bacteria, i.e. K. pneumoniae and E. coli with 22 mm zone of inhibition and one gram-positive bacterium i.e. M. luteus with 19 mm zone of inhibition. The methanolic extract at 0.0781mg/ml concentration showed least antibacterial activity against all tested bacteria produced a zone of inhibition between 10 to 12 mm while petroleum ether extract of same concentration had moderate antibacterial activity against S. flexneri (15 mm zone of inhibition). It can be concluded that novel compounds like flavonoids, tannins, saponins, alkaloid, and polyphenolic compounds in A. aspera leaves have potent antimicrobial property