Studies On The Chemical Constituents Of Three Medicinal Plants And The Related ?-glucosidase Inhibitory Activity

Alpha-glucosidase inhibitors(AGIs)are a class of oral hypoglycemic agents that are extensively used for managing type II diabetes and its associated disorders.Currently,three commercialized drugs,i.e.,acarbose,miglitol and voglibose,are AGIs.The major limitations associated with these drugs are the strict and repetitive dosing schedule and a high incidence of gastrointestinal disturbances that include flatulence,abdominal distension,borborygmus and diarrhea(Ceriello,2005).Therefore,novel AGIs with less side effects and better patient compliance must be discovered during the development of antidiabetic drugs.In our previous research,inotolactones A and B,two lanostane-type triterpenoids isolated from the submerged culture of Inonotus obliquus,exhibited potent ?-glucosidase inhibitory activity.Additionally,it was reported that chemical constituents of Abies firma,Withania somnifera,and Physalis pubescens shared similar skeleton with inotolactones A and B.It indicated that in-depth investigation into the chemical constituents of these three plants may lead to the discovery of more ?-glucosidase inhibitors.After extensive reviewing the chemical and pharmacological research of Abies firma,Withania somnifera,and Physalis pubescens,the chemical constituents of them were isolated,identified,and subjected to ?-glucosidase inhibitory activity evaluation.As a result,twelve compounds were isolated through chromatography separation(silica gel,ODS C-18,MCI and the preparative high performance liquid chromatography)from Abies firma,Withania somnifera,and Physalis pubescens.On the basis of physicochemical properties and extensive spectroscopic analysis(IR,UV,MS,NMR),the chemical structures of these compounds were elucidated.Compound 1 was elucidated as a flavonoid,5 was identified as a monoterpenoid,while compounds 2,3,4,6 were identified as steroids,compounds 7-10 were kavalactones.Among all the compounds,compounds 3?4?5 and 6 were isolated from the Abies genus for the first time.The compounds were evaluated for their ?-glucosidase inhibitory activities.Compound 10 have a good performance in restraining ?-glucosidase enzyme,which represented the first report on the ?-glucosidase inhibitory activity of kavalactones.