最新山莴苣过长沙与甜菊之活成分探索PPT课件.ppt
山莴苣过长沙与甜菊之活成分探索Studies on the Active Components from Lactuca indica,Bacopa monnieri and Stevia rebaudiananBecause the elderly population has been gradually increasing and life style changes,the mortality rate pertaining to diabetes mellitus has significantly raised in Taiwan.Currently,the use of insulin injections and oral hypoglycemic agents failed to control this disease effectively.In China,the Chinese medicine has been outstanding on the treatment of diabetes for thousand years.Although several folk medicines for the diabetes are useful,most of them need to establish their effectiveness.In this study,we would like to search the active principles and evaluate clinical use to serve as lead compound for the development of the novel antidiabetic drugs.In our preliminary screening tests,we found that the extracts of Lactuca indica(Compositae)and Bacopa monnieri(Scrophulariaceae)exhibited apparent hypoglycemic activities.The fresh L.indica was extracted with 70%acetone and repeatedly chromatographed,resulted in the isolation of thirteen compounds including four new compounds.Based on the spectroscopic data and chemical analysis,the structures of these new compounds were determined as lactucain A(10),lactucain B(11),lactucain C(12),and lactucaside(13).The whole plant material of B.monnieri was extracted with MeOH.By means of various column chromatographic separations,twenty-four compounds were isolated including five new compounds.Their structures were elucidated as bacopaside III(18),bacopasaponin G(19),bacopasides A(21),bacopasides B(28),and bacopasides C(30)by spectral and chemical methods.We have tested all compounds isolated from L.indica and B.monnieri for antihyperglycemic and antihypertensive activities.Six compounds,lactucain C(12),lactucaside(13),luteolin 7-O-b-D-glucuronide(6),calcerorioside B(25),and caffeic acid(31)have shown the remarkable antihyperglycemic activities.Furthermore,quercetin(1),bacopasaponin C(14),and bacopasapnin G(19)have displayed the pronounced antihypertensive activities.Stevioside was extracted from the leaves of Stevia rebaudiana(Compositae)and used as a natural sweetening agent.Isosteviol was obtained by acid hydrolysis of stevioside containing antidiabetic and antihypertensive activities.In order to study the bioactivity of isosteviol derivatives,microbial transformations have been used to introduce hydroxyl groups on the structure of isosteviol.By screening thirty microorganisms,Cunninghamella bainieri,Actinoplanes sp.,Mucor recurvatus,and Cunninghamella blakesleeana were selected for the biotransformation of isosteviol and obtained eight metabolites.Among them,five metabolites are the new compounds,including ent-11,12-dihydroxy-16-ketobeyeran-19-oic acid(39),ent-11,12,17-trihydroxy-16-ketobeyeran-19-oic acid(40),ent-12,15-dihydroxy-16-ketobeyeran-19-oic acid(41),ent-7,15-dihydroxy-16-ketobeyeran-19-oic acid(42),and ent-9-hydroxy-16-ketobeyeran-19-oic acid(43).Structure elucidation of these compounds was established through spectroscopic data.In addition,metabolites were tested for antihyperglycemic and antihypertensive activities.The results showed to be less active than isosteviol.
