1, 5-dicaffeoylquinic acid, an α-glucosidase inhibitor from the root of Dorema ammoniacum D. Don

Dorema ammoniacum D. Don (Apiaceae family) is a perennial plant whose oleo- gum resin is used as a natural remedy for various diseases, especially chronic bronchitis, and asthma. In the present study, hydromethanolic extract of D. ammoniacum root was subjected to phytochemical analyses and α-glucosidase inhibitory potentials of the isolated compounds were assessed.Silica gel (normal and reversed phases) and Sephadex® LH-20 column chromatographies were used for the isolation and purification of the compounds. Structures of the compounds were characterized by 1D and 2D nuclear magnetic resonance (NMR) techniques. All the isolated compounds were assessed for their in vitro α-glucosidase inhibitory activity in comparison with acarbose, a standard drug.Two phloroacetophenone glycosides; echisoside (1) and pleoside (2), along with dihydroferulic acid-4-O-β-D-glucopyranoside (3), and β-resorcylic acid (4), and two caffeoylquinic acid derivatives; chlorogenic acid (5) and 1, 5-dicaffeoylquinic acid (cynarin, 6) were isolated. Among the isolated compounds, the α-glucosidase inhibitory effect of 1,5-dicaffeoylquinic acid was found as 76.9% of the acarbose activity at 750 μM (IC50 value of acarbose).Considerable α-glucosidase inhibitory effect of 1,5-dicaffeoylquinic acid makes it an appropriate candidate for further studies in the development of new natural antidiabetic drugs.