In Vitro Evaluation of Antimicrobial Activity of Crude Extract from Plants Diospyros peregrina  , Coccinia grandis   and Swietenia macrophylla

Purpose: The aim of the present study was to investigate antimicrobial activity of methanol extract of Diospyros peregrina fruits (MEDP), Coccinia grandis leaves (MECG) and Swietenia macrophylla barks (MESM).
Methods: MEDP, MECG and MESM were examined against some selective gram positive and gram negative bacterial (20) and fungal (4) strains. Preliminary antimicrobial activity was evaluated by agar disc diffusion method. Minimum inhibitory concentration was determined by tube dilution (MIC) whilst minimum bactericidal concentration (MBC) and minimum fungicidal concentration (MFC) were determined by agar diffusion method.
Results: MEDP and MESM both have shown highest sensitivity against Escherichia coli strains. MEDP was found resistant to Sarcina luteus and Bacillus spp whereas MESM was resistant to all Shigella strains. MECG has shown major activity against Staphylococcus aureus, Escherichia coli, Shigella dysenteriae, Shigella soneii and Pseudomonas aeruginosa; whilst resistant to Shigella flexneri and Shigella boydii. Against fungi strains extracts were found effective at higher concentrations. Candida albicans has shown highest sensitivity whilst Penicillium spp. was least effective to all three extracts.
Conclusion: The study confirms that MEDP, MECG, MESM all possess antimicrobial activity with different potency against variety of selected microorganisms. The differentiating activities of these three extracts encourage developing a novel broad spectrum antimicrobial herbal formulation in future.

Keywords
Diospyros peregrina, Coccinia grandis, Swietenia macrophylla, Antimicrobial activity, Ciprofloxacin, Griseofulvin.