Abstract

Antimicrobial activity of extracts of certain herbs including Acacia modesta (leaf and stem), Artimisia absinthium (leaf and stem), Nigella sativa (seeds) and Saussurea lappa (root) was evaluated against three Gram positive and two Gram negative microorganisms. The Gram positive organisms included Bacillus subtalis (ATCC 6633), Entereococcus faecalis (ATCC 14506) and Staphylococcus aureus (ATCC 6538) and the Gram negative organisms included Pseudomonas aeruginosa (ATCC 27853) and Salmonella typhi (ATCC 14028). Methanolic, hot water and cold water extracts of these plants were taken for antibacterial assay through Discs agar diffusion technique using commercial filter paper discs applied on inoculated Muellar Hinton agar plates. The objective of this study was to explore the curative powers of these herbs that exist in nature as a tool to counter disease causing agents. The maximum zone of inhibition of 18 mm of methanolic extract of N. sativawas observed against B. subtalis and S. aureus. Similarly, the maximum zone of inhibition of 18 mm of cold water extract of N. sativa against S. aureus and methanolic extract of Saussurea lappa against S. aureus and Pseudomonas aeruginosa was also observed. The antibacterial action was compared with the effect of ceftriaxone, ceftriaxone sodium, cefuroxine, ciprofloxacin, gentamycine, levofloxacin, metronidazole and tranexamic acid that were used as standered drugs. Based on the results obtained in this study, it may be concluded that plant extracts of A. modesta, A. absinthium, N. sativa and Saussurea lappa have a stronger and broader spectrum of antimicrobial activity against a number of food borne bacteria.

Key words: Herbs, methanolic extract, Acacia modesta, Bacillus subtalis,gentamycine, gram negative, gram positive.