Tissue culture of some lichens and screening of their antioxidant, antityrosinase and antibacterial properties.

Lichen species Usnea ghattensis, Heterodermia podocarpa, Arthothelium awasthii and Parmotrema tinctorum have been cultured in vitro and screened for their antioxidant, antimicrobial and antityrosinase potential using different assay systems. The methanol extract of lichens showed antioxidant, antimicrobial and antityrosinase activities according to the order Usnea ghattensis > Arthothelium awasthii > Heterodermia podocarpa > Parmotrema tinctorum. The IC(50) values for the antioxidant and antityrosinase activities of U. ghattensis and A. awasthii were less than or equivalent to that of standard antioxidants and tyrosinase inhibitors. The methanol extracts of the lichen cultures Usnea ghattensis and Arthothelium awasthii were effective against Bacillus licheniformis, Bacillus megaterium, Bacillus subtilis and Staphylococcus aureus. The minimum inhibitory concentration (MIC) of the extract was found to be between 5 and 10 microg extract/mL. The results suggested that the extract of lichen cultures, U. ghattensis and A. awasthii, could be of use as an easily accessible source of natural antioxidants, tyrosinase inhibitory and antimicrobial properties as possible food supplements or in the pharmaceutical industry. Copyright (c) 2007 John Wiley & Sons, Ltd.