Lichens: traditional use and biological activities

Lichens are a stable symbiotic association between photobiont (algae and/or cyanobacteria) and mycobiont (fungi). They are utilized in traditional medicine for ages and documented in various pharmacopeia throughout the world. India is having a rich diversity of lichen species represented by about 2400 species. The tribal inhabitant around forests and other difficult terrains acquired unique knowledge about the use of much wide flora and fauna. Most of these are either lesser known or unknown to the outside world. The treasure of traditional knowledge if subjected to scientific scrutiny could benefit humankind in many ways. They produce unique secondary metabolites through various metabolic pathways and are known to exhibit a wide array of bioactivities. We have reviewed the literature for traditional knowledge of the lichen species and biological activities reported to study its inter-relationship. It was observed that that still a major percentage of lichens have remained unexplored. These lichens may have immense potential; and if analysed could be used in pharmaceutical, nutraceutical, cosmetic industries, and many more.