Phytochemicals and Antibacterial Activity of Leaf and Stem Extracts of Ageratum conyzoides (Linn) on Some Clinical Isolates

Abstract

Phytochemicals and antibacterial activity of leaf and stem extracts of Ageratum conyzoides on four clinical isolates, Staphylococcus aureus, Salmonella typhi, Escherichia coli and Pseudomonas areuginosa were investigated. Filtrates from ethanol extract of each of the powdered samples of the leaves and stem of A. conyzoides were evaporated to thick residues. 1 g each of these residues was dissolved in 5 ml of distilled water followed by double dilution to obtain concentrations of 200, 100, 50, 25, 12.5 and 6.25 mg/ml. Ciprofloxacin and distilled water were used as positive and negative controls, respectively. Antibacterial activity was assayed using Agar-well diffusion technique while the MIC was determined from the curve of square of radius diameter of inhibition against log concentration of the extract. Results showed that the leaf and stem of A. conyzoides contain comparable amounts of the phytochemicals with higher contents of flavonoid (0.97-0.98 %), saponin (0.97-0.98 %), and alkaloids (0.90 %) than tannin (0.187-0.188 %) and phenol (0.022 %). The extracts of A. conyzoides showed concentration-dependent activity against all the test bacterial isolates. The test organisms were found to be susceptible to the extracts at concentration of ? 50 mg/ml except S. typhi and P. aeruginosa that were susceptible to the stem extract at ?25 and ?100 mg/ml, respectively, whereas, for ciprofloxacin, some were susceptible even at very low concentration of 6.25 mg/ml. The MIC values were in the range of 69.18-75.86 mg/ml, 36.3-144.54 mg/ml and 7.59-38.0 mg/ml for the leaves and stem extracts and ciprofloxacin, respectively. The extracts could therefore be used as a broad spectrum antibacterial agent.