Usimines A−C, Bioactive Usnic Acid Derivatives from the Antarctic Lichen Stereocaulon alpinum
摘要:
Usimines A-C (1-3), three new usnic acid derivatives, have been isolated from a MeOH extract of the Antarctic lichen Stereocaulon alpinum by various chromatographic methods. The structures of 1-3 were determined by analysis of their spectroscopic data (NMR, UV, MS) and by chemical methods. The known compound usnic acid (4) was also obtained. Compounds 1-4 showed moderate inhibitory activity against therapeutically targeted protein tyrosine phosphatase 113 (PTP1B).