GC-MS profile, usnic acid quantification and in vitro investigation of biopharmaceutical potential of Physconia venusta (Ach.) Poelt. lichen growing in Algeria

INTRODUCTION: Lichens are complex symbiotic organisms that generate various bioactive compounds with significant therapeutic value. We sought to investigate the chemical composition and bioactivity of the acetone extract of the Algerian lichen Physconia venusta (Ach.) Poelt.
METHODS: Phytochemical screening was performed using GC-MS. The antibacterial activity was assessed against Escherichia coli, Pseudomonas aeruginosa, Salmonella enteritidis, Salmonella typhi, Staphylococcus aureus, listeria monocytogenes, and Bacillus subtilis using agar diffusion test with the determination of the minimal inhibition concentration (MIC), while the antioxidant activity was determined using different chemical methods (DPPH, ABTS, CUPRAC, reducing power, superoxide anion scavenging, β-carotene bleaching, and metal chelate). Additionally, cytotoxic activity was tested using Artemia salina (Brine shrimp) bioassay.
RESULTS: The studied extract exhibits intense antibacterial activity against E. coli and S. aureus with inhibition diameters of 28±0.01 and 22±0.01 mm respectively, with the MIC value of 6.25 mg/ml and a selectivity index of 2.8. The obtained extract showed different antioxidant trends depending on the selected assay. GC-MS analysis revealed the presence of many secondary metabolites.
DISCUSSION AND CONCLUSION: P. venusta, a type of lichen, is a potential source of bioactive substances that could be used in pharmaceuticals.