Bioactive Terphenyls Isolated from the Antarctic Lichen Stereocaulon alpinum

Abstract

Three p-terphenyls (2？4)―2-hydroxy-3,5-dimethoxy-p-terphenyl (2), 2-hydroxy-3,6-dimethoxy-p-terphenyl (3), and 2,3,5,6-tetramethoxy-p-terphenyl (4)―were iso-lated for the first time as natural products along with seven known compounds (1, 5？10) from the Antarctic lichen Stereocaulon alpinum. Structures of the new compounds were elucidated by com-prehensive analyses of 1D and 2D NMR and HREIMS experiments. Compound 3 exhibited cyto-toxicity against HCT116 cells with the IC50 value of 3.76 ± 0.03 μM and also inhibited NO production in LPS-induced RAW264.7 macrophages with the IC50 value of 22.82 ± 0.015 μM.