Evaluation of the antioxidant activity and Citotoxic potential of lichen forming fungal species of the family Parmeliaceae (Ascomycota)

Lichens produce a variety of secondary metabolites with important biological properties. This study analyzed the antioxidant activity and cytotoxic potential of selected Parmeliaceae lichens using in vitro methods and HPLC analysis. Methanolic extracts were obtained from five species: Hypogymnia physodes (L.), Parmotrema pseudotinctorum (Abbayes), Usnea subfloridana (Stirt.), Lethariella canariensis (Ach.) and Lethariella intricate (Moris). Their antioxidant capacities were assessed through DPPH, FRAP, ORAC, and Folin tests, while cytotoxicity was examined in breast adenocarcinoma (MCF7) and hepatocellular carcinoma (HepG2) cell lines via MTT viability assay.Results showed significant antioxidant activity, with Parmotrema pseudotinctorum exhibiting the highest ORAC and Folin values. Regarding cytotoxicity, Usnea subfloridana and Hypogymnia physodes demonstrated notable growth inhibition in MCF7 and HepG2, particularly at intermediate concentrations. Parmotrema pseudotinctorum showed moderate inhibition, more pronounced at lower doses. HPLC analysis identified bioactive compounds such as physodic acid, lecanoric acid, and usnic acid, which correlate with the observed antioxidant and cytotoxic activities. These findings highlight lichens as a potential source of therapeutic secondary metabolites, warranting further research to explore their medicinal applications.