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

TY - JOUR

T1 - 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

AU - Schrader, Eva

AU - Wein, Silvia

AU - Kristiansen, Karsten

AU - Christensen, Lars Porskjær

AU - Rimbach, Gerald

AU - Wolffram, Siegfried

PY - 2012/12

Y1 - 2012/12

N2 - 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.

AB - 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.

KW - Db/db mice

KW - Peroxisome proliferator-activated receptor-γ

KW - Plant extracts

KW - Type 2 diabetes

U2 - 10.1007/s11130-012-0322-0

DO - 10.1007/s11130-012-0322-0

M3 - Journal article

SN - 0921-9668

VL - 67

SP - 377

EP - 383

JO - Plant Foods for Human Nutrition

JF - Plant Foods for Human Nutrition

IS - 4

ER -