ABSTRACT
Objective: The study deals with the antimicrobial activity of five solvent extracts of roots of Caesaria tomentosa against seven microorganisms: two gram-positive (Staphylococcus aureus and Bacillus subtilis), three gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa and Salmonella typhimrium) and two fungal strains (Candida albicans and Aspergillus niger). Methods: Roots of C. tomentosa were extracted with different solvents(n-hexane, ethanol, chloroform, acetone and water) and were subjected to antibacterial as well as antifungal screening by Well Diffusion Method. The Minimum Inhibitory Concentration(MIC) was also performed by two-fold dilution. Results: The maximum inhibition zone at 50μg/ml concentration of n-hexane was 32 mm. These indicate that some active substances in C. tomentosa dissolved in varying degrees in the five solvents. The MIC for n-hexane was 1.6 μg/ml for S. aureus leading to a conclusion that the n-hexane extract was found to be the most potent. Conclusion: All extracts were very effective against S. aureus. As for the solvents, the n-hexane extract had the best inhibitory effect among five solvents tested.