Estimation of trace elements and in vitro biological activities of lichens extracts

Abstract

Infectious diseases caused by etiological agents are still a major threat to public health. Their impact is particularly large in developing countries due to relative unavailability of medicine and the emergence of widespread drug resistance. In the current research, trace metals were detected in lichens species through inductively coupled plasma atomic emission spectroscopy. The antimicrobial potency of Pseudevernia furfruracea, Physcia species, Dermatocarpon vellerum and Parmellia species (lichens) extracts have been investigated against three local clinical bacterial isolates i.e. Escherichia coli, Pseudomonas aeruginosa and Staphylococcus epidermidis through various agar disc and well diffusion methods. The antioxidant potential effect was also evaluated by DPPH and ABTS.+ free radical scavenging methods. Phytochemical constituents were screened through thin layer chromatography (TLC) and qualitative methods. Methanolic extract of P. furfruracea, Physcia spp, and D. vellerum showed a significant inhibition of S. epidermidis (14.3±1.7mm, 12.3±2.0mm, and 11.3±0.9mm) by pouring method of disc diffusion. Moderate zone of inhibition (8.0±1.4 mm) against S. epidermidis was observed by methanolic extract of Parmellia spp, through spreading method. All the results were evaluated by ANOVA and LSD tests at p<0.05. The diethyl ether extracts showed considerable antioxidant potential activity with 80%, 81%, 79% and 66%. Thin layer chromatography profiling gave us the idea about the presence of phytochemical constituents such as tannins, phenols, saponins, and terpenoids. Various Rf values on silica gel plates provided the valuable clues about polarity and the selection of solvents for separation of phytochemicals. Significant inhibition of E. coli was also observed through TLC-Bioautography. The findings revealed the considerable inhibitory and antioxidant effect of lichens may be due to the presence of bioactive compounds. Therefore, lichens could be a potential source of new antimicrobial and antioxidant agents.