Abstract

Several medicinal plant extracts having an antimicrobial property and those extracts are used to treat the infections caused by many microorganisms. This study aimed to assess the antimicrobial activity of Syzygium aromaticum (clove) ethanolic extracts. The extracts of clove were prepared in 70% ethanol by cold extraction process. Antimicrobial activity of different concentration of clove extracts was investigated on Bacillus subtillis, Enterococcus faecalis, Escherichia coli, Proteus vulgaris, Klebsiella quasipneumoniae, Pseudomonas aeruginosa, Shigella dysenteriae, Salmonella enterica subsp. enterica serovar Typhi, Staphylococcus aureus, Staphylococcus epidermidis, Candida albicans, Saccharomyces cerevisiae using Modified agar well diffusion method and diameter of ZOI was measured. The broth macro-dilution dilution method was used to determine the MIC and MBC/MFC of clove extracts on these above-mentioned organisms. Klebsiella quasipneumoniae, Pseudomonas aeruginosa and Shigella dysenteriae were found resistant to clove ethanolic extract. The lower concentration of the clove ethanolic extract (6.25mg/ml, 12.50mg/ml, 25 mg/ml and 50 mg/ml) on Enterococcus faecalis, Proteus vulgaris, Salmonella enterica Typhi, Staphylococcus aureus and Staphylococcus epidermidis were found insensitive, however the 100mg/ml concentration of this extract on these bacteria showed the diameter of ZOI 9.65±0.41mm, 10.12±0.70mm, 8.71±0.86mm, 17.52±0.50mm and 17.31±0.68mm respectively.  The lower concentration of clove ethanolic extract (6.25mg/ml, 12.5mg/ml and 25 mg/ml) were insensitive to Bacillus subtilis and Escherichia coli however, 50 mg/ml concentration of this extract showed the diameter of ZOI 12.59±1.13mm and 10.32±0.79mm respectively. Similarly, 100 mg/ml concentration of this extract showed the diameter of ZOI 14.75±0.67mm and 13.13±0.41mm on these bacteria respectively. The MBC of this extract for Bacillus subtilis, Enterococcus faecalis, Escherichia coli, Proteus vulgaris, Salmonella enterica Typhi, Staphylococcus aureus and Staphylococcus epidermidis were 0.78±0.00 mg/ml, 2.60±0.90 mg/ml, 5.21±1.80 mg/ml, 5.21±1.80 mg/ml, 6.25±0.00 mg/ml, 2.60±0.90 mg/ml, 5.21±1.80 mg/ml respectively. MFC of this extract on the Candida albicans and Saccharomyces cerevisiae were 1.30±0.45 mg/ml and 0.78±0.00 mg/ ml respectively. This finding confirmed that clove ethanolic extract had a potent antibacterial and antifungal activity. Thus, further research is imperative to explore the in-vivo antimicrobial activity and cytotoxicity analysis to suggest the clove ethanolic extract as the alternative treatment in various microbial infections.