Inhibitory Effects of Hydrolysable Tannins on Lipid Accumulation in 3T3-L1 Cells.

Obesity is currently the most common cause of metabolic diseases including type 2 diabetes and hyperlipidemia. Obesity results from excess lipid accumulation in adipose tissue. Several studies have investigated the inhibitory effects of natural plant-derived products on adipocyte differentiation and lipid accumulation. In this study, we examined the effect of hydrolysable tannins composed of gallic acid and glucose on adipocyte differentiation in 3T3-L1 cells. 1,2,3,4,6-Penta-O-galloyl-ß-D-glucose (PGG) (1), a representative gallotannin, inhibited lipid accumulation in 3T3-L1 cells, whereas ellagitannins (tellimagrandin I, eugeniin and casuarictin) did not. The expression of adipocyte differentiation-related genes, including peroxisome proliferator activator γ2 (Pparγ2), CCAAT/enhancer binding protein α (C/EBPα) and adipocyte fatty acid binding protein (aP2), was significantly suppressed in PGG (1)-treated 3T3-L1 cells beginning at day 2 after induction of differentiation. While PGG (1) did not directly reduce Pparγ2 expression, it reduced the expression of its target genes in mature adipocytes. In addition, PGG (1) treatment inhibited mitotic clonal expansion, one of earliest events of adipocyte differentiation. These findings indicate that PGG (1) has an inhibitory effect on adipocyte differentiation through the suppression of mitotic clonal expansion.

Inhibitory Effects of Indirubin-3'-oxime Derivatives on Lipid Accumulation in 3T3-L1 Cells.

Obesity elevates the risk of cardiovascular disease and has been strongly associated with increases in the incidence of many metabolic diseases. Therefore, prevention of obesity leads to the prevention of metabolic diseases. In light of this, substances that exert anti-obesity effects are crucial for the prevention of obesity. Indirubin, a 3,2' bisindole isomer of indigo, is the active component of the traditional Chinese medicine used for the treatment of chronic myelocytic leukemia. In particular, indirubin-3'-oxime (1) was shown to inhibit the differentiation of adipocytes. In this study, we investigated the inhibitory effects of nine indirubin-3'-oxime derivatives against lipid accumulation during differentiation in 3T3-L1 cells. Among the compounds tested, 5-methoxyindirubin-3'-oxime (2) and 6-bromoindirubin-3'-oxime (7) at 5 µM exhibited significantly stronger inhibitory activity than indirubin-3'-oxime (1). Furthermore, 5-methoxyindirubin-3'-oxime (2) and 6-bromoindirubin-3'-oxime (7) markedly suppressed the expression of CCAAT/enhancer-binding protein α, peroxisome proliferator activator γ2, and adipocyte protein 2, both of which are key adipogenic regulators at the intermediate stage of adipocyte differentiation. Our results demonstrate that 5-methoxyindirubin-3'-oxime (2) and 6-bromoindirubin-3'-oxime (7) significantly down-regulated lipid accumulation during differentiation of 3T3-L1 cells, suggesting their potential as novel therapeutic drugs against the development of obesity.

[A Method Based on Ru(bpy)3 3+ Electrogenerated Chemiluminescence for Assessment of Antioxidant Property of Naturally Occurring Antioxidants].

We developed a flow injection analysis (FIA) method based on tris(2,2'-bipyridine)ruthenium(III) [Ru(bpy)3 3+] electrogenerated chemiluminescence for assessment of antioxidant property. The hydroxyl radical (∙OH) were generated by H2O photolysis using an ultraviolet/H2O photoreactor. The reactor comprised a polytetrafluoroethylene tube, a quartz container, and a low-pressure mercury lamp that predominantly emitted radiation at around 185 nm. When the hydroxyl radical and Ru(bpy)3 3+ were in contact, chemiluminescence was generated as background emission. The background emission decreased when antioxidant samples were injected to the system. The antioxidant property of the naturally occurring antioxidants tested are listed herein, starting with the highest: gallic acid>ascorbic acid>quercetin. Moreover, our method allowed a sample throughput of approximately 100 samples/h. The proposed high throughput method can be used to assess the antioxidant property of the naturally occurring antioxidants.

Inhibitory effects of compounds isolated from the dried branches and leaves of murta (Myrceugenia euosma) on lipid accumulation in 3T3-L1 cells.

As obesity is a global health concern the demand for anti-obesity drugs is high. In this study, we investigated the anti-obesity effect of the dried branches and leaves of murta (Myrceugenia euosma Legrand, Myrtaceae). A methanol extract of the dried branches and leaves of murta inhibited adipogenesis in 3T3-L1 cells. Three known flavanones-cryptostrobin (1), pinocembrin (4), and 5,7-dihydroxy-6,8-dimethylflavanone (6), and three chalcones-2',6'-dihydroxy-3'-methyl-4'-methoxychalcone (2), pinostrobin chalcone (3), and 2',6'-dihydroxy-4'-methoxy-3',5'-dimethylchalcone (5) were isolated from the active fraction. Structures of these compounds were identified using various spectral data. Each of these compounds also inhibited adipogenesis in 3T3-L1 cells. In particular, compound 3 was a more potent inhibitor of triglyceride accumulation than the positive control berberine. Gene expression studies revealed that treatment of 3T3-L1 cells with 3 lowers the expression levels of CCAAT/enhancer-binding protein α and peroxisome proliferator activator γ2 during adipogenesis without affecting cell viability. Treatment of 3T3-L1 cells with 3 reduced the expression levels of mRNAs encoding sterol regulatory element-binding protein 1c and several lipogenic enzymes, including fatty acid synthase and stearoyl CoA desaturase-1. These results indicate that the methanol extract and compounds isolated from the dried branches and leaves of murta exert their anti-obesity effects through the inhibition of adipogenesis.

Determination of Miglitol by Column-Switching Ion-Pair HPLC with Tris(2,2'-bipyridine)ruthenium(II)-Electrogenerated Chemiluminescence Detection.

We have developed a highly sensitive, simple method for the quantitative determination of miglitol in standard serum samples using column-switching ion-pair HPLC with tris(2,2'-bipyridine)ruthenium(II)-electrogenerated chemiluminescence detection. The serum samples were directly injected into a column-switching HPLC system with a Shim-pack MAYI-SCX precolumn to remove the serum matrix. Chromatographic separation of miglitol was achieved on a TSKgel ODS 100-V column using a mobile phase containing sodium 1-octanesulfonate as an ion-pair reagent. The detection and quantification limits of miglitol were 3 and 10 ng/mL, respectively. The calibration curve for miglitol in the serum samples showed good linearity (r(2)=0.9997) in the range of 10-2500 ng/mL. The recovery rate of miglitol from the serum samples was more than 94% as calculated from blank serum samples spiked with miglitol 50, 100, 500, 1000, and 2000 ng/mL. Therefore, this method can be applied to routine therapeutic monitoring of miglitol in serum samples.

Inhibitory Effects of Gymnema (Gymnema sylvestre) Leaves on Tumour Promotion in Two-Stage Mouse Skin Carcinogenesis.

Ethanol extracts of gymnema (Gymnema sylvestre) leaves exhibited marked antitumour-promoting activity in an in vivo two-stage carcinogenesis test in mice using 7,12-dimethylbenz[a]anthracene as an initiator and 12-O-tetradecanoylphorbol-13-acetate (TPA) as a promoter. From the active fraction of the ethanol extract of the gymnema leaves, three triterpenoids were isolated and identified. These compounds were evaluated for their inhibitory effects on TPA-induced inflammation (1 µg/ear) in mice. The tested compounds showed marked anti-inflammatory effects, with a 50% inhibitory dose of 50-555 nmol/ear.

Selective detection of hydroxyl radical scavenging capacity based on electrogenerated chemiluminescence detection using tris(2,2'-bipyridine)ruthenium(III) by flow injection analysis.

We describe a new method for detecting hydroxyl radical scavenging capacity based on tris(2,2'-bipyridine)ruthenium(III) [Ru(bpy)(3)(3+)] chemiluminescence and flow injection analysis. Hydroxyl radicals were generated by the Fenton reaction. The scavenging capacity of the six antioxidants tested decreased in the following order: edaravone>L-tryptophan>gallic acid>Trolox>N-acetyl-L-cysteine>ascorbic acid. The proposed method allowed a sample throughput of about 80 samples/h. The six antioxidants were found to inhibit chemiluminescence intensity of Ru(bpy)(3)(2+). The proposed method is a rapid, selective, and accurate procedure for the study of hydroxyl radical scavenging capacity by Ru(bpy)(3)(3+) chemiluminescence.