In vitro and in silico investigation of the multifunctional bioactivity of the lichen Oxneriopsis bassiae (ach.) S.Y. Kondr., Upreti & Hur

Lichens are recognized as rich sources of structurally diverse secondary metabolites with significant pharmacological potential. Several lichen-derived compounds exhibit antioxidant and enzyme inhibitory activities, particularly against carbohydrate-metabolizing enzymes involved in the regulation of postprandial hyperglycemia. The present study aimed to characterize the phytochemical profile and evaluate the carbohydrate-metabolizing enzyme inhibitory potential of the crude methanolic extract of Oxneriopsis bassiae , along with its antioxidant and photoprotective properties. Preliminary phytochemical screening confirmed the presence of phenols, flavonoids, tannins, and anthraquinones. Chemical characterization was performed using Thin-Layer Chromatography (TLC), Fourier-Transform Infrared Spectroscopy (FTIR), and Liquid Chromatography–Mass Spectrometry (LC-MS). TLC analysis revealed prominent bands in mid-polar solvent systems, particularly hexane: ethyl acetate (40:60 and 20:80). FTIR spectra showed strong absorption peaks between 1700 and 1640 cm −1 , indicating C O stretching of conjugated ketones typical of anthraquinone structures. LC-MS analysis identified ten compounds in positive ionization mode and eight in negative mode, with parietin detected as a major anthraquinone. The extract exhibited notable antioxidant activity in DPPH, ABTS, FRAP, and phosphomolybdenum assays. Significant inhibition of carbohydrate-metabolizing enzymes was observed, particularly α-glucosidase (IC₅₀ = 95.25 μg/mL) and α-amylase (IC₅₀ = 495.24 μg/mL). Molecular docking and molecular dynamics simulations further confirmed stable interactions of identified compounds within enzyme active sites, supporting its potential antioxidant, antidiabetic, and UV-protective applications.