An insight into the variation of the antioxidative and antibacterial activity of extracts from populations of the subalpine and montane lichen Cetraria islandica

Lichens are supra-organismal symbiotic systems found in most environments. Environmental factors, such as temperature, altitude, precipitation, UV irradiation, or pathogens, significantly influence the physiology of lichens, and thus their secondary metabolism. The thalli of the same lichen species from different environments exhibit variation in the production of secondary metabolites and protective pigments. We selected two populations of the lichen Cetraria islandica from habitats differing in altitude, temperature, and precipitation. Then we compared their antioxidative and antibacterial activity. The lichen thalli were divided into two parts: the upper parts were exposed to light and the lower parts hidden from extensive radiation. The results show that the thalli from harsh alpine environments have higher 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical scavenging activity suggesting better tolerance to oxidative stress. On the other hand, the individuals from milder montane environments generally produce more secondary metabolites, leading to increased antibacterial activity of the extracts. The extracts of C. islandica containing fumarprotocetraric and paraconic acids exhibit inhibitory effects against gram-positive bacteria (e.g. Staphylococcus aureus) and some lower activity against gram-negative bacteria (e.g. Escherichia coli)