In-vitro antimicrobial activity of crude acetone extract of the stem bark of Combretum molle against selected bacterial pathogens

Abstract

Drug resistance by clinically important pathogens is now a worldwide problem with far-reaching consequences especially considering that the emergence of drug resistance is now outpacing the development of new drugs. Plants have been used for many generations for healing purposes, and screening of extracts of these plants has often yielded positive outcomes. This study was aimed at evaluating the antibacterial potential of the stem bark ofCombretum molle, in a bid to identify potential sources of cheap starting materials for the synthesis of new drugs to address the growing antimicrobial resistance. Various solvents were used for plant extraction. The agar well diffusion technique was used to screen for antimicrobial activity of the solvent extracts against Helicobacter pylori PE 252C,Streptococcus pyogenes ATCC 49399, Pseudomonas aeruginosa ATCC 15442 andPlesiomonas shigelloides ATCC 51903. Minimum inhibitory concentration (MIC50) of the most active extracts was determined by the broth dilution method. Fisher’s exact test indicated a high antimicrobial activity with zones of inhibition ranging from 0 to 32 mm. Acetone was the most potent extract with its MIC50 ranging from 0.078 to 5.0 mg/ml. There was no statistically significant difference (P>0.05) in the potency of four extracts (acetone, methanol, ethanol and ethyl acetate) and antibiotic (ciprofloxacin), which served as positive control. Therefore, the acetone extract of C. molle contain therapeutically useful compounds, justifying the use of the plant in traditional medicine. Key words: Combretum molle, medicinal plants, antimicrobial activity, minimum inhibitory concentration.