Phenolic Secondary Metabolites and Antiradical and Antibacterial Activities of Different Extracts of (L.) Weber ex F.H.Wigg from Călimani Mountains, Romania.

Phenolic compounds represent an essential bioactive metabolites group with numerous pharmaceutical applications. Our study aims to identify and quantify phenolic constituents of various liquid and dry extracts of (L.) Weber ex F.H. Wigg () from Calimani Mountains, Romania, and investigate their bioactivities. The extracts in acetone, 96% ethanol, and water with the same dried lichen/solvent ratio (/) were obtained through two conventional techniques: maceration (UBA, UBE, and UBW) and Soxhlet extraction (UBA, UBE, and UBW). High-performance liquid chromatography with diode-array detection (HPLC-DAD) was performed for usnic acid (UA) and different polyphenols quantification. Then, the total phenolic content (TPC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free-radical scavenging activity (AA) were determined through spectrophotometric methods. Using the disc diffusion method (DDM), the antibacterial activity was evaluated against Gram-positive and Gram-negative bacteria known for their pathogenicity: (ATCC 25923), (ATCC 49619), (ATCC 27853), and (ATCC 13883). All extracts contain phenolic compounds expressed as TPC values. Five lichen extracts display various UA contents; this significant metabolite was not detected in UBW. Six polyphenols from the standards mixture were quantified only in ethanol and water extracts; UBE has all individual polyphenols, while UBE shows only two. Three polyphenols were detected in UBW, but none was found in UBW. All extracts had antiradical activity; however, only ethanol and acetone extracts proved inhibitory activity against , , and . In contrast, was strongly resistant (IZD = 0). Data analysis evidenced a high positive correlation between the phenolic constituents and bioactivities of each extract. Associating these extracts' properties with both conventional techniques used for their preparation revealed the extraction conditions' significant influence on lichen extracts metabolites profiling, with a powerful impact on their pharmacological potential.