In-vitro antimicrobial activity of Ageratum conyzoides (Linn) on clinical isolates of Helicobacter pylori

Abstract

The present study evaluates the antimicrobial activity of fractionated extracts ofAgeratum conyzoides in a bid to isolate the active constituents of the plant with anti-Helicobacter pylori activity. Helicobacter pylori was isolated from the specimens following standard microbiology procedures and isolates subjected to pure fractions of plant extracts for antimicrobial assays. Extracts of A. conyzoides was fractionated by silica gel and thin layer chromatography to obtain pure fractions (17). Fractions 23 - 30 and 31 - 36 were so close and had crystals; it was assumed that they had the same active components, so they were combined and considered as one (Fractions 23 - 36). The disk diffusion method was used to determine the susceptibility of 15 strains of H. pylori to the fractions. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) for the most active fraction was also determined by the broth dilution method. Results were analyzed by the Fisher’s exact test. All the fractions tested demonstrated antimicrobial activity with zone diameters of inhibition between 0 – 30 mm. However, two of the 17 fractions [23 - 36(100%Hex-Hex/EA20%) and 69 - 83(Hex/EA80%)] demonstrated very potent activities. The lowest MIC and MBC recorded were 0.002 and 0.016 mg/mL respectively. However the MIC of the fractions ranged from 0.016 - 0.500 mg/mL for fractions 23 - 36 and 0.002 - 0.500 mg/mL for fractions 69 - 83. The MBC of the fractions ranged from 0.063 - 0.500 mg/mL for fractions 23 - 36; 0.016 - 1.000 mg/mL for fractions 69 - 83. There was a statistically significant difference (P 0.05) in their activities both for the MIC and MBC. It is concluded that this plant may contain compounds with therapeutic activity, which may be found in fractions 23 - 36 (100%Hex-Hex/EA20%) and 69 - 83(Hex/EA80%). Key words: Antimicrobial activity, medicinal plant, minimum inhibitory concentration, minimum bactericidal concentration, Helicobacter pylori, antimicrobial resistance.