ABSTRACT
Plant flavonoids have a variety of biological properties. In a previous study, we found that the tea of the Asian dayflower, Commelina communis L., decreased the body weight gain in high-fat diet-fed mice. In this study, we studied the anti-adipogenic ability of a flavonoid orientin that is found in abundance in C. communis. Orientin repressed the accumulation of intracellular triglyceride (TG) in mouse adipocyte 3T3-L1 cells. The treatment with orientin also decreased the mRNA levels of the genes involved in adipogenesis, lipogenesis, lipolysis, and TG synthesis, and reduced the release of glycerol. Orientin lowered the expression of CCAAT/enhancer binding protein (C/EBP) δ in the early stage of adipogenesis, leading to a decrease in the expression of the adipogenic master transcription factors such as peroxisome proliferator-activated receptor (PPAR) γ and C/EBPα. Moreover, the anti-adipogenic effect of orientin repressed the phosphorylation of Akt and subsequent phosphorylation of forkhead box protein O1 (FOXO1), which inhibits the transcription of the Ppar gene. These results indicate that a plant flavonoid orientin suppressed the expression of the Pparγ gene through repression of C/ebpδ expression and inhibition of the phosphoinositide 3-kinase /Akt-FOXO1 signaling in adipocytes.
Subject(s)
Adipocytes/drug effects , Adipogenesis/drug effects , Anti-Obesity Agents/pharmacology , CCAAT-Enhancer-Binding Protein-delta/antagonists & inhibitors , Flavonoids/pharmacology , Gene Expression Regulation, Developmental/drug effects , Glucosides/pharmacology , PPAR gamma/antagonists & inhibitors , 3-Phosphoinositide-Dependent Protein Kinases/antagonists & inhibitors , 3-Phosphoinositide-Dependent Protein Kinases/metabolism , 3T3-L1 Cells , Adipocytes/enzymology , Adipocytes/metabolism , Animals , CCAAT-Enhancer-Binding Protein-delta/genetics , CCAAT-Enhancer-Binding Protein-delta/metabolism , CCAAT-Enhancer-Binding Proteins/antagonists & inhibitors , CCAAT-Enhancer-Binding Proteins/genetics , CCAAT-Enhancer-Binding Proteins/metabolism , Forkhead Box Protein O1/antagonists & inhibitors , Forkhead Box Protein O1/metabolism , Glycerol/metabolism , Lipolysis/drug effects , Mice , PPAR gamma/genetics , PPAR gamma/metabolism , Phosphorylation/drug effects , Protein Processing, Post-Translational/drug effects , Proto-Oncogene Proteins c-akt/antagonists & inhibitors , Proto-Oncogene Proteins c-akt/metabolism , Signal Transduction/drug effects , Triglycerides/metabolismABSTRACT
Our recent studies have shown that the hydrogels prepared by blending clay, a dispersant of clay, and a polyelectrolyte (sodium polyacrylate (PAAS)) possess excellent mechanical properties. In order to clarify the mechanism of the toughness, we have so far investigated the effects of the composition, molecular mass of the polymer, and kinds of polymers on the mechanical properties. This study has focused upon the mechanical properties and structures of the clay/PAAS gels using three kinds of smectite clay minerals such as synthetic hectorite (laponite XLG), saponite (sumecton-SA), montmorillonite (kunipia-F), whose particle size becomes larger according to the sequence. Laponite/PAAS and sumecton/PAAS gels were quite tough for high compression, whereas kunipia-F/PAAS did not gelate. In comparison between sumecton/PAAS gel and laponite/PAAS gel, the mechanical property of the former gel was poorer than that of the latter gel due to the inhomogeneous distribution of clay platelets in the gel. Synchrotron small-angle X-ray scattering experiments revealed that their clay platelets laid down in the stretching direction under elongation. Furthermore, it was found that sumecton/PAAS gel under elongation was arranged with an interparticle distance of ~6.3 nm in the direction perpendicular to the stretching. Such local ordering under elongation may originate in local aggregation of sumecton platelets in the original state without elongation.
