Antibacterial and Antioxidant Activity of Lichens Usnea rubrotincta, Ramalina dumeticola, Cladonia verticillata and Their Chemical Constituents

Abstract

The present study was carried out to evaluate the antibacterial and antioxidant activity of extract and chemical constituents of Usnea rubrotincta, Ramalina dumeticola and Cladonia verticillata. Acetone extract of U. rubrotincta showed promising antibacterial activity against Gram positive bacteria Bacillus subtilis with the lowest Minimal Inhibitory Concentration (MIC) value of (15.63 g/mL). Six secondary metabolites were isolated using Preparative High Performance Liquid Chromatography (PHPLC) method from the two bioactive lichens U. rubrotincta and R. dumeticola (compound 1 -6). Among all six compounds, compound (1) exhibited strongest activity against both the tested Gram positive bacteria at 7.81 g/mL. Compound (6) had 69.57% scavenging activity against DPPH free radical while the rest only showed below 50% scavenging activity. This is the first evaluation of antibacterial activity of lichens found in Malaysia and to our knowledge, this is the first report of antibacterial and antioxidant activity of compound (3) and (5).