title: Plant extracts of winter savory, purple coneflower, buckwheat and black elder activate PPAR-γ in COS-1 cells but do not lower blood glucose in Db/db mice in vivo.
abstract: The aim of this study was to investigate possible blood glucose-lowering effects of plant extracts in vivo for which prior to this a peroxisome proliferator-activated receptor-γ activity in vitro was observed. The ability of extracts of winter savory, purple coneflower, buckwheat and black elder to dose-dependently activate peroxisome proliferator-activated receptor-γ was determined in a reporter gene assay in COS-1 cells. For evaluation of glucose-lowering effects in vivo, db/db mice were fed a diet containing either rosiglitazone (0.02 g/kg diet, positive control) or one of the plant extracts (0.1 and 1 g/kg diet) for four weeks. Apart from glucose, insulin, triacylglycerols, non-esterified fatty acids, cholesterol and adiponectin were determined in plasma. All plant extracts showed a dose-dependent peroxisome proliferator-activated receptor-γ-activating effect in vitro. In db/db mice none of the plant extracts exerted glucose-lowering effects at the used dosages compared to rosiglitazone. Non-esterified fatty acids, triacylglycerols, cholesterol, insulin and adiponectin in plasma were not altered by the plant extracts as well. Although dose-dependent peroxisome proliferator-activated receptor-γ activity could be shown in COS-1 cells, the experiments in db/db mice lacked to confirm any anti-diabetic effect of the plant extracts in vivo and emphasizes the importance of verifying cell culture data using an appropriate in vivo model.
authors.affiliation: Institute of Animal Nutrition and Physiology, Christian-Albrechts-Universität zu Kiel, Hermann-Rodewald-Str. 9, 24118 Kiel, Germany. eva.schrader@iba.fau.de
authors.forename: Eva
authors.initials: E
authors.lastname: Schrader
authors.forename: Silvia
authors.initials: S
authors.lastname: Wein
authors.forename: Karsten
authors.initials: K
authors.lastname: Kristiansen
authors.forename: Lars P
authors.initials: LP
authors.lastname: Christensen
authors.forename: Gerald
authors.initials: G
authors.lastname: Rimbach
authors.forename: Siegfried
authors.initials: S
authors.lastname: Wolffram
mesh_terms: D052242:Adiponectin / Q000097:blood; D000818:Animals; D001786:Blood Glucose / Q000187:drug effects; D001835:Body Weight; D019556:COS Cells; D002522:Chlorocebus aethiops; D002784:Cholesterol / Q000097:blood; D003921:Diabetes Mellitus, Experimental / Q000188:drug therapy; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy* / Q000503:physiopathology; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D020900:Echinacea / Q000737:chemistry*; D019612:Fagopyrum / Q000737:chemistry*; D005260:Female; D007328:Insulin / Q000097:blood; D051379:Mice; D047495:PPAR gamma / Q000187:drug effects*; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D000077154:Rosiglitazone; D027924:Sambucus nigra / Q000737:chemistry*; D031362:Satureja / Q000737:chemistry*; D045162:Thiazolidinediones / Q000494:pharmacology; D014280:Triglycerides / Q000097:blood
chemical_list: D052242:Adiponectin; D001786:Blood Glucose; D007328:Insulin; D047495:PPAR gamma; D010936:Plant Extracts; D045162:Thiazolidinediones; D014280:Triglycerides; D000077154:Rosiglitazone; D002784:Cholesterol