Phenanthrenes from Dendrobium senile and their pancreatic lipase inhibitory activity

From the whole plant of Dendrobium senile, a new phenanthrene namely 2,5,7-trihydroxy-4-methoxyphenanthrene (1) was isolated, together with seven known compounds including moscatin (2), 2,5-dihydroxy-4,9-dimethoxyphenanthrene (3), moscatilin (4), aloifol I (5), 4,4',8,8'-tetramethoxy[1,1'-biphenanthrene]-2,2',7,7'-tetrol (6), 2,2',7,7'-tetrahydroxy-4,4'-dimethoxy-1,1'-biphenanthrene (7) and bleformin G (8). The structure of the new compound was elucidated by analysis of its spectroscopic data. Moscatin (2) and 2,5-dihydroxy-4,9-dimethoxyphenanthrene (3) showed appreciable pancreatic lipase inhibitory effects when compared with the positive control orlistat.