Evaluation of antimicrobial efficacy of extracts from the bark of a semi arid plant <i>Albizia lebbeck</i> (L.) Benth

Abstract

In the present study, use of ethnomedicinal plant/ plant parts for the treatment of disease with little or no side effect is investigated against the pathogens related to infectious diseases. Bark of <i>Albizia lebbeck</i> (L.) Benth was collected and air dried and soxhlet extracted by using standard methods for flavonoid, alkaloid, steroid and different solvents. These extracts were then tested for antimicrobial activity using disc diffusion method. Minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and total activity (TA) were also calculated. Statistical analysis like mean value and standard deviation were calculated for the test bacteria and fungi. Data was analyzed by one-way analysis of variance and <i>P </i> values were considered significant at <i>P ></i> 0.005. Among the seven extracts, methanol extract exhibited highest inhibition zone (20 mm) against <i>R. planticola.</i> <i>P. aeruginosa, S. aureus</i>, and <i>R. planticola</i> were observed to be more susceptible pathogens in the investigation followed by <i>B. subtilis, E. aerogenes</i>,and <i> E. coli.</i> Bound flavonoid and methanolic extracts of the bark of <i>A. lebbeck</i> were found to be most bioactive. The range of MIC and MBC of extracts recorded was 0.625-0.078 mg/mL and 0.312- 0.039 mg/mL, respectively. The lowest MIC value 0.078 mg/mL was recorded against <i>R. planticola</i>, indicating significant antimicrobial potential of test extracts. High values of TA were observed against <i>R. planticola</i>, followed by <i>S. aureus</i>. Results of the present study revealed that the bark extracts of <i>A. lebbeck</i> showed great antimicrobial potential against the tested microorganisms and may be exploited for future antimicrobial drugs.