Steroids from the Antarctic lichen Ramalina terebrata and their chemotaxonomical significance

Four steroids (1–4) were isolated from the Antarctic lichen, Ramalina terebrata (Ramalinaceae), along with a lupane type triterpenoid (5) and an anthraquinone derivative (6). The structures of the isolated compounds were characterized by comprehensive spectroscopic analyses and LC-MS analysis. The isolated compounds were identified as brassicasterol (1), (22E,24R)-24-methylcholesta-5,22-diene-3β,7α-diol (2), ergosterol peroxide (3), 9,11-dehydroergosterol peroxide (4), lupeol (5) and parietin (6). It is the first report of the identification of steroids and a triterpenoid from R. terebrata. The chemotaxonomical significance of the isolated compounds is also discussed.