Secondary metabolite variability in lichen genus Usnea in India: A potential source for bioprospection

Abstract

The species of lichen genus Usnea are well known for their worldwide distribution and medicinal properties due to presence of usnic acid. The genus is represented by more than 300 species in the world out of which 57 species are reported from India. In India, the species of Usnea grows profusely in higher altitudes of Western Ghats and Himalayan regions. 20 different secondary metabolites are known from Indian Usnea species which have potential biological and physiological significance. Salazinic acid, stictic acid, norstictic acid and barbatic acid are the most dominant secondary metabolites along with usnic acid. Apart from the natural thalli the cultivated mycobiont of Usnea species also produced many of these compounds in culture conditions. The secondary compounds present in Usnea species are significant source of natural products for commercial uses.