Bioactive Secondary Metabolites Isolated from the Antarctic Lichen Himantormia lugubris

Abstract

Two new depsidones, himantormiones A and B (1 and 2) were isolated from the Antarctic lichen, Himantormia lugubris (Parmeliaceae), together with seven known compounds (3-9). The structures of the new compounds (1 and 2) were determined by means of spectroscopic analyses, including 1D and 2D NMR and HR-MS. The isolated compounds were evaluated for their antimicrobial and cytotoxic activities, where himantormione B (2) exhibited an inhibitory effect against Staphylococcus aureus with the IC50 value of 7.01 ± 0.85 mM. Compound 2 also exhibited strong cytotoxic activity against HCT116 cells (colon cancer) with the EC50 value of 1.11 ± 0.85 μM, where that of the positive control, 5-fluouracil, was 9.4 ± 1.90 μM.