Chemical constituents from the Antarctic lichen Usnea aurantiaco-atra and their chemotaxonomic significance

Abstract

Chemical investigation of the Antarctic lichen Usnea aurantiaco-atra led to the isolation and identification of eight compounds, including a dibenzofuran derivative (1), three phenolics (2, 7, 8), a p-terphenyl (3), and three sterols (4–6). The structures of the isolated compounds (1–8) were elucidated by 1H and 13C NMR spectroscopic analyses and comparisons with previously reported data. All compounds (1–8) were isolated from this species for the first time. The current study is also the first report of the identification of two compounds, pentamethoxy-p-terphenyl and 9,11-dehydroergosterol peroxide, from the Usnea genus. Meanwhile, the chemotaxonomic value of all isolates is also discussed in this paper.