Assessment of bactericidal activity of some lichen extracts by disc diffusion assay

In the presented study, thirty-two natural extracts obtained from lichen species; P. reticulatum, P. tinctorum, Herpothallon sp., H. leucomelos, R. celastri, Leptogium sp. and P. crinitum, were evaluated for their bactericidal activity against three gram positive and three gram negative human pathogens. The investigation was performed by agar-disc diffusion assay and bactericidal activity of each lichen extract was measured using zone of inhibition. It was observed that methanol lichen extracts had the maximum efficacy whereas hexane extracts had the least bactericidal potential. Overall, P. reticulatum found to be the most anti-bacterial effective species and C. subradiata was the least potent species. According to all the result, it was concluded that these lichen species can be studied further as great source of bactericidal agents due to their high potency as antibiotics in in vitro models