title: alpha-Glucosidase and alpha-amylase inhibitory activities of saponins from traditional Chinese medicines in the treatment of diabetes mellitus.
abstract: Extracts of eleven traditional Chinese medicines (TCM) with a reputation of usefulness in treating diabetes mellitus were examined for alpha-glucosidase and alpha-amylase inhibitory activities in vitro. The extract with the highest activity was selected for further characterization. The extract of the root bark of Aralia taibaiensis (EAT) outperformed other extracts in the assays with IC50 values of 0.48 +/- 0.01 mg/mL (BSG), 0.41 +/- 0.02mg/mL (SCG), 0.61 +/- .03mg/mL (BLA) and 0.77 +/- 0.03mg/mL (PPA), respectively. To identify which constituents were responsible for the activities, thirteen triterpenoid saponins were isolated from EAT and examined for their inhibitory effects against alpha-glucosidase and alpha-amylase. The results revealed that saponins 2, 3, 4 (IC50: 0.83 +/- 0.05 microM for BSG and IC50: 0.72 +/- 0.03 microM for SCG), 5, 6, 7, 9, 10, 11 and 12 (IC50: 1.07 +/- 0.04 micro.M for BSG and IC50: 0.93 +/- 0.05 micro.M for SCG) showed alpha-glucosidase inhibitory activities, while 2, 3, 4 (IC50: 0.93 +/- 0.04 micro.M for PPA), 5, 6, 7, 9, 10, 11 and 12 (IC50: 1.02 +/- 0.03 micro.M for PPA) possessed significant alpha-amylase inhibitory activities. In addition, the structure-activity relationship of the thirteen saponins was discussed based on their structure features and diabetes mellitus related activities. It is suggested that the glucuronic acid unit at C-3 of the aglycone is the imperative functional group of the antidiabetic activities, and two characteristic structural features are responsible for the remarkable alpha-glucosidase and alpha-amylase inhibitory activities.
authors.affiliation: Department of Pharmacy, Xijing Hospital, Fourth Military Medical University, Yangling, PR China.
authors.forename: Fang
authors.initials: F
authors.lastname: Dou
authors.forename: Miaomiao
authors.initials: M
authors.lastname: Xi
authors.forename: Junxian
authors.initials: J
authors.lastname: Wang
authors.forename: Xiangrong
authors.initials: X
authors.lastname: Tian
authors.forename: Liangjian
authors.initials: L
authors.lastname: Hong
authors.forename: Haifeng
authors.initials: H
authors.lastname: Tang
authors.forename: Aidong
authors.initials: A
authors.lastname: Wen
mesh_terms: D027983:Aralia / Q000737:chemistry; D002240:Carbohydrate Sequence; D003920:Diabetes Mellitus / Q000188:drug therapy; D004365:Drugs, Chinese Herbal / Q000737:chemistry / Q000494:pharmacology*; D004791:Enzyme Inhibitors; D065089:Glycoside Hydrolase Inhibitors; D007004:Hypoglycemic Agents / Q000737:chemistry / Q000494:pharmacology*; D008516:Medicine, Chinese Traditional; D008969:Molecular Sequence Data; D010179:Pancreas / Q000201:enzymology; D024301:Plant Bark / Q000737:chemistry; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D018517:Plant Roots / Q000737:chemistry; D012503:Saponins / Q000737:chemistry / Q000494:pharmacology*; D014315:Triterpenes / Q000494:pharmacology; D000516:alpha-Amylases / Q000037:antagonists & inhibitors*
chemical_list: D004365:Drugs, Chinese Herbal; D004791:Enzyme Inhibitors; D065089:Glycoside Hydrolase Inhibitors; D007004:Hypoglycemic Agents; D010936:Plant Extracts; D012503:Saponins; D014315:Triterpenes; D000516:alpha-Amylases