Phytochemical Profiling and Antioxidant and Enzymatic Evaluation of Extracts from the Antarctic Lichens Polycauliona candelaria and Placopsis antarctica

The high prevalence and incidence of neurodegenerative diseases pose a public health challenge and drive the search for alternative treatments. This study determined the chemical composition of hydroalcoholic extracts from the Antarctic species Polycauliona candelaria and Placopsis antarctica and evaluated their antioxidant and cholinesterase-inhibitory potential through in vitro assays and molecular docking. Using UHPLC/ESI/QToF/MS, 16 compounds were tentatively identified in P. candelaria and 11 in P. antarctica. P. antarctica exhibited greater antioxidant capacity (2.69 ± 0.15 mg GAE/g in TPC, and an IC50 for DPPH and ABTS of 330.64 ± 0.02 and 63.33 ± 0.02 µg/mL, respectively) and inhibitory activity (IC50 for AChE and BuChE of 654.42 ± 0.03 and 845.58 ± 0.01 µg/mL, respectively) similar to P. candelaria. Molecular docking analyses revealed that gyrophoric acid and stictic acid possess outstanding binding affinities, comparable to the drug galantamine, by effectively interacting with the catalytic sites of the enzymes. This is the first report on the chemical compounds present in extracts of P. antarctica and P. candelaria and contributes to the understanding of their therapeutic potential.