antioxidant.

Lichens are organisms which are formed through symbiotic association of fungi and algae or cyanobacteria. Lichen produces a great variety of secondary metabolites with various biological activities including antimicrobial, antiviral, antitumour, antioxidant, antihervivore, insecticidal, allelochemical and allergenic action. These compounds play a major role in providing photoprotection against intense radiation and can be used as an important candidate for antipyretic and analgesic drugs. Lichen metabolites act as major factor in metal homeostasis and pollution tolerance of lichen. This review describes the biological activities of secondary metabolites produced from lichen.