Lipase inhibitors from dendrobium senile

Abstract

Obesity is characterized as an abnormal lipid metabolism due the imbalance between the energy intake and output. Pancreatic lipase is secreted by the pancreas and plays an important role in the digestion and absorption of lipids in the small intestine. Inhibition of pancreatic lipase enzyme can reduce dietary fat absorption which will lead to loss of weight and finally result in hypocholesterolemia and hypoglycemia. From the whole plant of Dendrobium senile, a new phenanthrene derivative was isolated, together with seven known compounds, including 2,5,7-trihydroxy-4-methoxyphenanthrene (1), moscatin (2), 2,5-dihydroxy-4,9-dimethoxyphenanthrene (3), moscatilin (4), aloifol I (5), 4,4ʹ,8,8ʹ-tetramethoxy[1,1ʹ-biphenanthrene]-2,2ʹ,7,7ʹ-tetrol (6), 2,2ʹ,7,7ʹ-tetrahydroxy-4,4ʹ-dimethoxy-1,1ʹ-biphenanthrene (7) and bleformin G (8). Their structures were characterized by NMR, UV, IR and MS spectroscopic methods. All the isolated compounds were evaluated for pancreatic lipase inhibitory activity. Moscatin (2) and 2,5-dihydroxy-4,9-dimethoxyphenanthrene (3) showed recognizable pancreatic lipase inhibitory activity with IC50 values of 57.6 ± 3.3 µM and 58.6 ± 3.4 µM, respectively, when compared with the positive control orlistat (IC50 0.031 ± 0.004 µM).