Introduction: Nowadays, antimicrobial resistance among bacteria and other pathogenic microorganisms is a serious threat to management of infectious diseases. Therefore, investigation of new metabolite from new resources such as lichens are the subject of many research groups.
Materials and methods: Acetone extract of two lichens of Glypholecia scabra and Rhizoplaca melanophthalm were prepared using a Soxhlet extraction. The antibacterial activities of the extracts were investigated on some Gram-positive and Gram-negative bacteria such as, Bacillus cereus, Bacillus subtilis, Staph aureus, Micrococcus luteus, Pseudomonas aeruginosa, Klebsiella pneumonia, Proteus vulgaris, Serratia marcessence, Escherichia coli using the Mueller Hinton Medium and Carbenicillin and Azithromycin standard antibiotics by Kirby’s method. Minimum inhibitory concentration and minimum bactericidal concentration of the extracts were determined.
Results: Extract of Glypholecia scabra showed significant effects on Gram-positive bacteria such as, Bacillus cereus, Bacillus subtilis, Staph aureus, and Micrococcus luteus and also on Gram-negative Proteus vulgaris, respectively, with MIC values of 0.16, 0.26, 1.04, 0.65 and 0.11 mg/ml.Extract of Rhizoplaca melanophthalma showed inhibitory effects on Gram-positive bacteria Bacillus cereus, B. subtilis, Micrococcus luteus and Staphylococcus aureus, respectively, with values of 0.04, 0.08, 1.04 and 0.16 mg/ml but had no effect on Gram-negative bacteria.
Discussion and conclusion: The antibacterial effect of Glypholecia scabra has not published before. The results of this research demonstrate the antibacterial effects of both Iranian native lichens. So acetone extract of the studied lichens maybe an alternative to chemical antibiotics that need to be studied more.