An Investigation of Antimicrobial Effects of Ethanol Extract of the Lichen Ramalina hyrcana Sipman on Human Disease-causing Bacteria

Infectious diseases are an important cause of mortality in the world. Because of resistance of some human pathogenic bacteria to antibiotics, use of natural and herbal medicine is increasing to control these factors. The aim of this study is to investigate the antibacterial effects of Ramalina hyrcana Sipman lichens against many Gram-positive and Gram-negative bacteria. The lichen ethanol extract was prepared by using a rotary machine. Nine standard strains of Gram- positive and Gram -negative bacteria were cultured in nutrient broth. The minimum inhibitory concentration (MIC) was determined by the micro dilution method. The results of this study showed that the lichen R. hyrcana extract in different concentrations inhibited both Gram-positive and Gram-negative bacteria. The results showed that the lichen extract of all concentrations inhibited of Staphylococcus aureus. After S. aureus bacteria inhibition, the minimum inhibitory concentrations are for Hafnia and Acinetobacter (12.5 ppm). According to the results and other reports in this area, lichen R. hyrcana extract could be introduced as a biological control agent. However, for the use of different lichen extracts for clinical application, the chemical analysis of extracts and clinical research is necessary.