Lichens are a group of composite organisms formed by the symbiotic relationship between the cyanobacteria or algae or both and fungi. In this study, a total of 84 lichen specimens were collected and identified from varying altitudes around the Kathmandu and Pokhara which were later identified to be as 61 different species belonging to 19 different genera. Methanol fractions of 16 specimens and dichloromethane (DCM) fraction of 21 specimens showed comparable antioxidant activities with commercial standards (BHA, Butylated hydroxyanisole, IC50=4.9±0.9 µg/ml) even at crude level. Similarly, DCM fraction of 17 lichens showed potential antimicrobial activity against a gram positive bacterium (Staphylococcus aureus) and DCM fractions of 45 lichens showed potential antimicrobial activity against a gram negative bacterium (Klebsiella pneumoniae).  And, DCM fraction of three lichens showed antifungal activity against Candida albicans. Likewise, methanol fraction of 39 lichens and DCM fractions of 74 lichens showed strong toxicity against brine shrimp larvae. After the preliminary screening, extracts from one particular species, Peltigera polydactylon which showed promising result with the antioxidant test was used for further analysis. Due to highly polar nature of the compounds present, reverse chromatography was performed followed by column chromatography. With the preconception that naturally occurring compounds can have an advantage in the therapeutic application over the synthetic compounds, lichens could be potential sources of bioactive natural products which could be commercialized with necessary further research.

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