In vitro antibacterial activity of acetone, methanol, petroleum ether, and diethyl ether extracts of three foliose lichen species Dirinaria picta, Dirinaria Papillulifera, and Dirinaria applanata have been investigated against two clinically significant human pathogenic bacteria (Gram-positive Staphylococcus aureus, MTCC 737 and Gram-negative Escherichia coli, MTCC 443) using agar cup diffusion method. Commercial drug streptomycin (1 mg/ml) was taken as a standard positive and 5% dimethyl sulphoxide (DMSO) as a negative control. All the extracts were found effective by showing the solvent dependent zone of inhibition. Largest zone of inhibition against E. coli by D. picta, D. papillulifera, and D. applanata have been recorded for acetone (37.1 ± 0.2 mm), methanol (23.5 ± 0.6 mm), and acetone (30.6 ± 0.4 mm) extracts, respectively. On the other hand, S. aureus was inhibited with maximum zone by methanol (23.6 ± 0.4 mm), diethyl ether (24.2 ± 0.4 mm), and acetone (21.6 ± 0.5 mm) extracts for D. picta, D. papillulifera, and D. applanata, respectively. The principal component analysis concluded that negative control (5% DMSO) does not affect the growth of test pathogens and most of the lichen extracts were more effective than the positive control.
Key words: In-vitro, Antibacterial potential, Dirinaria species, Agar cup diffusion method, Zone of inhibition, Human test pathogen.
|
