Green tea seed oil reduces weight gain in C57BL/6J mice and influences adipocyte differentiation by suppressing peroxisome proliferator-activated receptor-γ

Antioxidant capacity of phenolic compounds separated from tea seed oil in vitro and in vivo

Tea seed oil is rich in phenols with good antioxidant capacity. However, the antioxidant capacity evaluation of tea seed oil polyphenols is not deep enough, which mainly focusing on the evaluation of the chemical system. Thirty-nine phenols were tentatively identified by UPLC-ESI-MS/MS analysis, including flavonoids and phenolic acids. The antioxidant capacity of phenol extracts was investigated in vitro and in vivo. The chemical assays showed the extracts had good proton and electron transfer capabilities. The CAA assay indicated the IC₅₀ of the extracts was 77.93 ± 4.80 µg/mL and cell antioxidant capacity of the extracts was 101.05 ± 6.70 μmol·QE/100 g of oil. The animal experiments suggested phenol extracts could significantly improve the organ index, reduce malondialdehyde content, and increase superoxide dismutase, glutathione peroxidase and total antioxidant capacity (p < 0.05). This study was contributed to the antioxidant capacity of phenol extracts of tea seed oil by comprehensive evaluation.

Optimization of aqueous enzymatic method for Camellia sinensis oil extraction and reuse of enzymes in the process

Aqueous enzymatic extraction of Camellia sinensis oil was studied. The results suggested that saponin removal pretreatment assisted by ultrasound was effective in decreasing emulsification and in enhancing the free oil recovery. After 70% isopropanol extraction for 30 min under ultrasound, the residue of C. sinensis seeds was further hydrolyzed with free cellulase and Alcalase for 5 h, and calcium ions were concurrently added during enzymatic hydrolysis (n_Ca²⁺: n_saponin = 1:2), and free oil recovery up to 94.14% was obtained. Separate immobilization and co-immobilization of Alcalase and cellulase were performed by alginate entrapment combined with glutaraldehyde crosslinking. Specific activity and recovery of activity for Alcalase and cellulase were acceptable. After immobilization, Alcalase and cellulase exhibited higher activity at a wider pH and temperature range. Reuse experiments of immobilized enzymes were conducted. The deactivation kinetics immobilized enzymes were simulated and half-life of immobilized enzyme was estimated. The results indicated that a magnetic supporter facilitated the recovery of immobilized enzymes from tea seed slurry, and that immobilized Alcalase and cellulase had good reusability.

Liver Histological Improvement After Administration of High-Dose Vitamin C in Guinea Pig with Nonalcoholic Steatohepatitis

Background: Vitamin C is a strong antioxidant, and the health effects of vitamin C megadoses have not been validated despite the apparent health benefits. Therefore, the present study sought to confirm the effects of vitamin C megadoses. Materials and Methods : Four groups of six guinea pigs were used. Each group was fed one of the following diets for three weeks: normal diet, methionine choline-deficient diet, methionine choline-deficient diet + vitamin C megadose (MCD + vit C 2.5 g/kg/day), and methionine-choline deficient diet + ursodeoxycholic acid (MCD + UDCA 30 mg/kg/day). The MCD diet was given to induce nonalcoholic steatohepatitis, and UDCA was used to treat nonalcoholic steatohepatitis. Three weeks after initial diet administration, the results of biochemical tests and liver biopsy were compared between the groups. Results: The cytoplasm state was similar in the MCD + vit C and MCD + UDCA groups, exhibiting clearing of the cytoplasm and ballooning degeneration. However, macrovesicular steatosis was not observed in the MCD + vit C group. Aspartate transaminase and alanine transaminase were elevated significantly following vitamin C administration. Conclusions: The present study confirmed that alone vitamin C megadoses are potential remedies for nonalcoholic steatohepatitis, based on the liver biopsy results of guinea pigs that were unable to synthesize vitamin C.

Flavonoids from Camellia sinensis (L.) O. Kuntze seed ameliorates TNF-α induced insulin resistance in HepG2 cells

The aim of this study is to discuss the non-catechin flavonoids (NCF) from Camellia sinensis (L.) O. Kuntze seed improving TNF-α impaired insulin stimulated glucose uptake and insulin signaling. Flavonoids had anti-metabolic syndrome and anti-inflammatory properties. It had widely been known for biological activity of catechins in tea, but very few research reports discussed the biological activity of non-catechin flavonoids in tea seed. We used HepG2 cell to treat with 5 μM insulin or with 5 μM insulin + 30 ng/ml TNF-α. Detecting the glucose concentration of medium, insulin decreased the glucose levels of medium meant that insulin promoted glucose uptake into cells, but TNF-α inhibited the glucose uptake effect of insulin. Furthermore, insulin increased the protein expressions of IR, IRS-1, IRS-2, PI3K-α, Akt/PKB, GLUT-2, AMPK, GCK, pyruvate kinase, and PPAR-γ. TNF-α activated p65 and MAPKs (p38, JNK1/2 and ERK1/2), iNOS and COX-2 which worsened the insulin signaling expressions of IR, IRS-1, IRS-2, PI3K-α, Akt/PKB, GLUT-2, AMPK, GCK, pyruvate kinase, and PPAR-γ. We added NCF (500, 1000, 2000 ppm) to cell with insulin and TNF-α. Not only glucose levels of medium were lowered, and the protein expressions of insulin signaling were increased, but p38, JNK1/2, iNOS and COX-2 were also reduced. NCF could ameliorate TNF-α induced insulin resistance through inhibiting p38, JNK1/2, iNOS and COX-2, and suggested that it might be used in the future to help control insulin resistance. This finding is the first report to present the discovery.

Adipocytes secreted leptin is a pro-tumor factor for survival of multiple myeloma under chemotherapy

Accumulating evidences have shown that adipokines secreted from adipocytes contributes to tumor development, especially leptin. However, underlying mechanisms remain unclear. This study aims to explore the effect of leptin on development and chemoresistance in multiple myeloma cells and the potential mechanism. Analysis of levels of adipokines including leptin and adiponectin in 28 multiple myeloma patients identified significantly higher leptin compared with 28 normal controls(P < 0.05), and leptin level was positively correlated with clinical stage, IgG, ER, and ß2MG. Next, by using co-culture system of myeloma and adipocytes, and pharmacologic enhancement of leptin, we found that increased growth of myeloma cells and reduced toxicity of bortezomib were best observed at 50 ng/ml of leptin, along with increased expression of cyclinD1, Bcl-2 and decreased caspase-3 expression. We also found that phosphorylated AKT and STAT3 but not the proteins expression reached peak after 1h and 6h treatment of leptin, respectively. By using AG490, an agent blocking the phosphorylation of AKT and ERK, the proliferation of myeloma cells was inhibited, as well as the phosphorylation of AKT and STAT3, even adding leptin. Taken together, our study demonstrated that up-regulated leptin could stimulate proliferation of myeloma and reduce the anti-tumor effect of chemotherapy possibly via activating AKT and STAT3 pathways, and leptin might be one of the potential therapeutic targets for treating myeloma.

Distribution of free, esterified, and insoluble bound forms of phenolics in tea seeds and their antioxidant activity

In this study, phenolic compounds in their phenolic extract (PE), free phenolic (FP), esterified phenolic (EFP), and insoluble bound phenolic (ISBP) forms were extracted from tea seeds and quantified using HPLC to obtain information on the phenolics that are present in tea seeds along with their antioxidant activities. The total phenolic content of the ISBP fraction was higher than that of the FP and EFP fractions. The phenolic acids in tea seeds exist either in esterified or glycosided forms. Moreover, hydroxycinnamic acid derivatives have been identified as important phenolic acid components in tea seeds. The ISBP fraction was an effective antioxidant based on the results obtained from the in vitro assays performed, which include the DPPH and 2,2-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)-derived nitrogen-centered radical scavenging activities, Fe³⁺-2,4,6-tripyridyl-s-triazine reducing ability, as well as Cu²⁺ and Fe²⁺ ion chelating effects.

Veratri Nigri Rhizoma et Radix (Veratrum nigrum L.) and Its Constituent Jervine Prevent Adipogenesis via Activation of the LKB1-AMPKα-ACC Axis In Vivo and In Vitro

This study was performed in order to investigate the antiobese effects of the ethanolic extract of Veratri Nigri Rhizoma et Radix (VN), a herb with limited usage, due to its toxicology. An HPLC analysis identified jervine as a constituent of VN. By an Oil Red O assay and a Real-Time RT-PCR assay, VN showed higher antiadipogenic effects than jervine. In high-fat diet- (HFD-) induced obese C57BL/6J mice, VN administration suppressed body weight gain. The levels of peroxisome proliferator-activated receptor gamma (PPARγ), CCAAT-enhancer-binding protein alpha (C/EBPα), adipocyte fatty-acid-binding protein (aP2), adiponectin, resistin, and LIPIN1 were suppressed by VN, while SIRT1 was upregulated. Furthermore, VN activated phosphorylation of the liver kinase B1- (LKB1-) AMP-activated protein kinase alpha- (AMPKα-) acetyl CoA carboxylase (ACC) axis. Further investigation of cotreatment of VN with the AMPK agonist AICAR or AMPK inhibitor Compound C showed that VN can activate the phosphorylation of AMPKα in compensation to the inhibition of Compound C. In conclusion, VN shows antiobesity effects in HFD-induced obese C57BL/6J mice. In 3T3-L1 adipocytes, VN has antiadipogenic features, which is due to activating the LKB1-AMPKα-ACC axis. These results suggest that VN has a potential benefit in preventing obesity.

Green tea supplementation benefits body composition and improves bone properties in obese female rats fed with high-fat diet and caloric restricted diet

This study investigated the effects of green tea polyphenols (GTP) supplementation on body composition, bone properties, and serum markers in obese rats fed a high-fat diet (HFD) or a caloric restricted diet (CRD). Forty-eight female rats were fed an HFD ad libitum for 4 months, and then either continued on the HFD or the CRD with or without 0.5% GTP in water. Body composition, bone efficacy, and serum markers were measured. We hypothesized that GTP supplementation would improve body composition, mitigate bone loss, and restore bone microstructure in obese animals fed either HFD or CRD. CRD lowered percent fat mass; bone mass and trabecular number of tibia, femur and lumbar vertebrae; femoral strength; trabecular and cortical thickness of tibia; insulin-like growth factor-I and leptin. CRD also increased percent fat-free mass; trabecular separation of tibia and femur; eroded surface of tibia; bone formation rate and erosion rate at tibia shaft; and adiponectin. GTP supplementation increased femoral mass and strength (P = .026), trabecular thickness (P = .012) and number (P = .019), and cortical thickness of tibia (P < .001), and decreased trabecular separation (P = .021), formation rate (P < .001), and eroded surface (P < .001) at proximal tibia, and insulin-like growth factor-I and leptin. There were significant interactions (diet type × GTP) on osteoblast surface/bone surface, mineral apposition rate at periosteal and endocortical bones, periosteal bone formation rate, and trabecular thickness at femur and lumbar vertebrate (P < .05). This study demonstrates that GTP supplementation for 4 months benefited body composition and improved bone microstructure and strength in obese rats fed with HFD or HFD followed by CRD diet.

Evaluation of green pepper (Capsicum annuum L.) juice on the weight gain and changes in lipid profile in C57BL/6 mice fed a high-fat diet

BACKGROUND

Capsicum pepper (green pepper, Capsicum annuum L.), a natural product available in many countries, is considered to be a food additive, with healthful or medical applications. The aim of this study was to evaluate green pepper juice for its potential to reduce weight gain and to determine its effects on lipid profiles in C57BL/6 mice fed a high-fat diet.

RESULTS

Mice given a high-fat diet with green pepper juice gained significantly less weight and showed a significant decrease in serum triglycerides, total cholesterol, low density lipoproteins, and alanine aminotransferase compared to mice given only a high-fat diet (P < 0.05). Systolic and diastolic blood pressure, heart rate, and blood glucose levels (determined by using the intraperitoneal glucose tolerance test) in mice administered green pepper juice were similar to those in mice in the control group. In addition, abdominal fat volume (subcutaneous and visceral), which was quantified by using 4.7 T magnetic resonance imaging, including multi-slice spin-echo T2-weighted images, in mice administered a high-fat diet with green pepper juice tended to decrease compared to the fat volume of mice administered only a high-fat diet.

CONCLUSION

These results suggest that green pepper juice, as a drink, may possibly be helpful in reducing weight gain by regulating the levels of serum lipids.

Protective effect of the standardized green tea seed extract on UVB-induced skin photoaging in hairless mice

BACKGROUND/OBJECTIVES

Ultraviolet B (UVB) irradiation on skin can induce production of reactive oxygen species (ROS), which cause expression of matrix metalloproteinases (MMPs) and collagen degradation. Thus, chronic exposure of skin to UVB irradiation leads to histological changes consistent with aging, such as wrinkling, abnormal pigmentation, and loss of elasticity. We investigated the protective effect of the standardized green tea seed extract (GSE) on UVB-induced skin photoaging in hairless mice.

MATERIALS/METHODS

Skin photoaging was induced by UVB irradiation on the back of Skh-1 hairless mice three times per week and UVB irradiation was performed for 10 weeks. Mice were divided into six groups; normal control, UVB irradiated control group, positive control (UVB + dietary supplement of vitamin C 100 mg/kg), GSE 10 mg/kg (UVB + dietary supplement of GSE 10 mg/kg), GSE 100 mg/kg (UVB + dietary supplement of GSE 100 mg/kg), and GSE 200 mg/kg (UVB + dietary supplement of GSE 200 mg/kg).

RESULTS

The dietary supplement GSE attenuated UVB irradiation-induced wrinkle formation and the decrease in density of dermal collagen fiber. In addition, results of the antioxidant analysis showed that GSE induced a significant increase in antioxidant enzyme activity compared with the UVB irradiation control group. Dietary supplementation with GSE 200 mg/kg resulted in a significant decrease in expression of MMP-1, MMP-3, and MMP-9 and an increase in expression of TIMP and type-1 collagen.

CONCLUSIONS

Findings of this study suggest that dietary supplement GSE could be useful in attenuation of UVB irradiation-induced skin photoaging and wrinkle formation due to regulation of antioxidant defense systems and MMPs expression.

Interaction of Veratrum nigrum with Panax ginseng against Obesity: A Sang-ban Relationship

Obesity has become a major health threat in developed countries. However, current medications for obesity are limited because of their adverse effects. Interest in natural products for the treatment of obesity is thus rapidly growing. Korean Medicine (KM) is characterized by the wide use of herbal formulas. However, the combination rule of herbal formulas in KM lacks experimental evidence. According to Shennong's Classic of Materia Medica, the earliest book of herbal medicine, Veratrum nigrum (VN) has antagonistic features against Panax ginseng (PG), and the PG-VN pair is strictly forbidden. In this study, we have shown the effects of PG, VN, and their combination on obesity in high-fat (HF) diet-induced obese mice and in 3T3-L1 cells. PG, VN, and PG-VN combination significantly reduced weight gain and the fat pad weight in HF diet-induced obese mice. They also significantly decreased lipid accumulation and the expressions of two major adipogenesis factors, PPARγ and C/EBPα, in 3T3-L1 cells. In addition, the PG-VN combination had synergistic effects compared with the mixture of extracts of PG and VN on inhibition of PPARγ and C/EBPα expressions at lower doses. These results indicate a new potential anti-obese pharmacotherapy and also provide scientific evidence supporting the usage of herbal combinations instead of mixtures in KM.

Novel synthesis of leucoside by enzymatic hydrolysis of tea seed extract

BACKGROUND

The application of tea seed extract (TSE) has been widely investigated owing to its biological activities. In this paper, two flavonol triglycosides found in TSE, camelliaside A (CamA) and camelliaside B (CamB), were subjected to hydrolysis in the presence of three commercial enzyme complexes of the Pectinex® series, 5XL, XXL and Ultra SP-L (Ultra).

RESULTS

XXL and 5XL induced stepwise deglycosylation of CamA and CamB to yield kaempferol diglycoside (nicotiflorin), kaempferol monoglycoside (astragalin) and kaempferol, while Ultra produced an additional new compound (1) that had not been observed in earlier studies. Upon hydrolysis of isolated CamA and CamB, compound (1) was obtained only from CamB. Both the molecular ion peak in liquid chromatography/mass spectrometry and the ¹H and ¹³C nuclear magnetic resonance spectra of (1) isolated by Ultra-induced hydrolysis of TSE indicated that (1) was kaempferol 3-O-β-xylopyranosyl (1 → 2)-β-glucopyranoside (leucoside), formed by selective hydrolysis of the rhamnosyl moiety of CamB.

CONCLUSION

Pure leucoside can be prepared by enzymatic partial hydrolysis of TSE. This is the first study to address the synthesis of pure leucoside from a natural source.

Green tea polyphenols benefits body composition and improves bone quality in long-term high-fat diet-induced obese rats

This study investigates the effects of green tea polyphenols (GTPs) on body composition and bone properties along with mechanisms in obese female rats. Thirty-six 3-month-old Sprague Dawley female rats were fed either a low-fat (LF) or a high-fat (HF) diet for 4 months. Animals in the LF diet group continued on an LF diet for additional 4 months, whereas those in the HF diet group were divided into 2 groups: with GTP (0.5%) or without in drinking water, in addition to an HF diet for another 4 months. Body composition, femur bone mass and strength, serum endocrine and proinflammatory cytokines, and liver glutathione peroxidase (GPX) protein expression were determined. We hypothesized that supplementation of GTP in drinking water would benefit body composition, enhance bone quality, and suppress obesity-related endocrines in HF diet-induced obese female rats and that such changes are related to an elevation of antioxidant capacity and a reduction of proinflammatory cytokine production. After 8 months, compared with the LF diet, the HF diet increased percentage of fat mass and serum insulin-like growth factor I and leptin levels; reduced percentage of fat-free mass, bone strength, and GPX protein expression; but had no effect on bone mineral density and serum adiponectin levels in the rats. Green tea polyphenol supplementation increased percentage of fat-free mass, bone mineral density and strength, and GPX protein expression and decreased percentage of fat mass, serum insulin-like growth factor I, leptin, adiponectin, and proinflammatory cytokines in the obese rats. This study shows that GTP supplementation benefited body composition and bone properties in obese rats possibly through enhancing antioxidant capacity and suppressing inflammation.

Fatty acid composition and antioxidant activity of tea (Camellia sinensis L.) seed oil extracted by optimized supercritical carbon dioxide

Seeds are another product in addition to leaves (raw materials for teas) of tea (Camellia sinensis L.) plant. The great increase of tea consumption in recent years raises the challenge of finding commercial applications for tea seeds. In the present study, supercritical carbon dioxide (SC-CO(2)) extraction edible oil from tea seed was carried out, response surface methodology (RSM) was used to optimize processing parameters including time (20-90 min), temperature (35-45 °C) and pressure (50-90 MPa). The fatty acid composition and antioxidant activity of the extracted oil was also investigated. The highest yield of oil (29.2 ± 0.6%) was obtained under optimal SC-CO(2) extraction conditions (45 °C, 89.7 min and 32 MPa, respectively), which was significantly higher (p < 0.05) than that (25.3 ± 1.0%) given by Soxhlet extraction. Meanwhile, tea seed oil extracted by SC-CO(2) contained approximately 80% unsaturated fatty acids and showed a much stronger scavenging ability on the DPPH radical than that extracted by Soxhlet. SC-CO(2) is a promising alternative for efficient extraction of edible oil from tea seed. Moreover, tea seed oil extracted by SC-CO(2) is highly edible and has good antioxidant activity, and therefore may play a potential role as a health-promoting food resource in human diets.

Isolation and anti-inflammatory effect of astragalin synthesized by enzymatic hydrolysis of tea seed extract

BACKGROUND

The application of tea seed extract (TSE) has been widely investigated because of its biological activities. In this paper, two flavonol triglycosides in TSE-camelliaside A (CamA) and camelliaside B (CamB)-were subjected to hydrolysis in the presence of two commercial enzyme complexes (Pectinex™ series): Smash and Mash.

RESULTS

Smash hydrolyzed only the xylosyl moiety of CamB, and the main product was kaempferol diglycoside (nicotiflorin, NF). On the other hand, Mash induced the hydrolysis of both CamA and CamB, and kaempferol monoglycoside (astragalin, AS) was found to be a main product. Pure AS with > 96% purity was prepared by enzymatic hydrolysis of TSE using Mash, and the chemical structure of AS was confirmed by (1)H- and (13)C-nuclear magnetic resonance analyses. The prepared pure AS showed anti-inflammatory activities by significantly inhibiting cellular nitrite oxide (IC(50) = 363 µg mL(-1)), prostaglandin E(2) (IC(50) = 134 µg mL(-1)) and interleukin-6 production (IC(50) = 289 µg mL(-1)) by lipopolysaccharide -stimulated RAW 264.7 cells.

CONCLUSION

It was concluded that pure AS can be prepared by enzymatic partial hydrolysis of TSE and employed as an anti-inflammatory material. This is the first study to address the preparation of pure AS from natural sources.

(-)-Epigallocatechin-3-gallate blocks 3T3-L1 adipose conversion by inhibition of cell proliferation and suppression of adipose phenotype expression

AIMS

A major objective in the treatment of obese individuals is the development of agents that reduce body fat and improve metabolic homeostasis. Among a variety of biological effects, green tea exerts an anti-obesity effect; however, the mechanisms behind its activity on adipose tissue are uncertain. Tea contains high levels of (-)-epigallocatechin-3-gallate (EGCG), which is one of its main bioactive substances. Therefore, we studied the effects of EGCG on mouse embryonic fibroblast-adipose like cell line (3T3-L1) preadipocyte proliferation and differentiation.

MAIN METHODS

3T3-L1 cells were incubated with physiologically attainable (0.1-1 μM) and pharmacological (5μM, 10μM) concentrations of EGCG for various lengths of time. Cell proliferation was assessed by cell counting and cell cycle analysis. Adipose conversion was evaluated by lipid accumulation and expression of CCAAT/enhancer binding protein alpha (C/EBPα) and peroxisome proliferator-activated receptor gamma (PPARγ) transcription factors.

KEY FINDINGS

A dose dependent suppressive effect on preadipocyte proliferation was observed, with the highest reduction in cell number at 10μM EGCG. On the other hand, adipose conversion was fully inhibited with 10μM EGCG. Flow-cytometric analysis showed that 3T3-L1 cells treated with EGCG underwent an arrest of cell cycle at G2/M. The inhibition of the expression of C/EBPα and PPARγ was accompanied by the inhibitory effect of EGCG. Microscopic observation showed that 3T3-L1 cells treated with EGCG maintained the fibroblastic shape and failed to accumulate cytoplasmic fat droplets even after the induction of differentiation.

SIGNIFICANCE

Our results suggest that EGCG reduces adipogenesis through an arrest of cell cycle and a blockage of adipose phenotype expression. These results also suggest that the anti-obesity activity of green tea may be partially attributed to its suppressive effects in adipogenesis.

Sida rhomboidea. Roxb leaf extract down-regulates expression of PPARγ2 and leptin genes in high fat diet fed C57BL/6J Mice and retards in vitro 3T3L1 pre-adipocyte differentiation

Sida rhomboidea. Roxb leaf extract (SRLE) is being used by the populace of North-East India to alleviate symptoms of diabetes and obesity. We have previously reported its hypolipidemic and anti-diabetic properties. In this study, we report the effect of SRLE on (i) in vivo modulation of genes controlling high fat diet (HFD) induced obesity and (ii) in vitro 3T3L1 pre-adipocyte differentiation and leptin release. Supplementation with SRLE significantly prevented HFD induced increment in bodyweight, plasma lipids and leptin, visceral adiposity and adipocyte hypertrophy. Also, SRLE supplementation reduced food intake, down regulated PPARγ2, SREBP1c, FAS and LEP expressions and up-regulated CPT-1 in epididymal adipose tissue compared to obese mice. In vitro adipogenesis of 3T3L1 pre-adipocytes was significantly retarded in the presence of SRLE extract. Also decreased triglyceride accumulation, leptin release and glyceraldehyde-3-Phosphate dehydrogenase activity along with higher glycerol release without significant alteration of viability of 3T3L1 pre-adipocytes, was recorded. Our findings suggest that prevention of HFD induced visceral adiposity is primarily by down regulation of PPARγ2 and leptin gene expression coupled with attenuation of food intake in C57BL/6J mice. SRLE induced prevention of pre-adipocytes differentiation, and leptin release further substantiated these findings and scientifically validates the potential application of SRLE as a therapeutic agent against obesity.

Oleanolic acid reduces markers of differentiation in 3T3-L1 adipocytes

Oleanolic acid is a triterpenoid compound that is widely present in vegetables, medicinal herbs, and other plants and has potent antioxidant and antiinflammatory properties. However, the potential of oleanolic acid to offset obesity is not clear. This study tested the hypothesis that oleanolic acid suppresses the differentiation of 3T3-L1 adipocytes by downregulating cellular induction of peroxisome proliferators-activated receptor γ (PPARγ) and cytidine-cytidine-adenosine-adenosine-thymidine (CCAAT) enhancer binding protein α (C/EBPα). The 3T3-L1 adipocytes were cultured and differentiated in Dulbecco modified Eagle medium containing 10% fetal bovine serum for 6 to 8 days in the absence and presence of 1 to 25 μmol/L oleanolic acid according to differentiating protocols. Nontoxic oleanolic acid, at 25 μmol/L or less, dose-dependently attenuated lipid accumulation in differentiated adipocytes as evidenced by Oil Red O staining. Western blot analysis showed that the induction of PPARγ and C/EBPα was markedly attenuated in differentiated and oleanolic acid-treated adipocytes at their transcriptional messenger RNA levels. Furthermore, this study examined whether oleanolic acid dampened the induction of visfatin, a proinflammatory and visceral fat-specific adipokine expressed in adipocytes. Visfatin expression was inhibited in differentiated adipocytes exposed to a PPARγ inhibitor GW9662. In addition, the visfatin production was significantly repressed in 25 μmol/L oleanolic acid-treated adipocytes, possibly through blocking PPARγ activation. These results demonstrate that oleanolic acid may be a promising agent to disturb adipocyte differentiation and suppress obesity-associated inflammation.

Polyphenols: planting the seeds of treatment for the metabolic syndrome

Greater understanding about the pathogenesis of metabolic syndrome and potential causes suggests that plant polyphenols might be useful as a treatment. Dietary excess energy can be stored in adipocytes, leading to the release of proinflammatory cytokines and adipose-related hormones that cause vascular injury. Plant polyphenols, organic compounds found in numerous plant species and their fruits, are being actively studied as potential treatments for components of the metabolic syndrome. Individual polyphenols that have been examined include resveratrol, quercetin, epigallocathechin-3-gallate, and curcumin. Resveratrol lowers weight, blood pressure, glucose, and insulin resistance in rodents, and a human trial is currently underway. Quercetin decreases lipid and glucose levels in obese rats, and in a human investigation of subjects with the metabolic syndrome has lowered blood pressure without significant alteration of lipids. Epigallocathechin-3-gallate-induced weight loss has attenuated glucose levels and insulin resistance in rodents and improved hemoglobin A(1c) and lipid in human studies. Plant extracts also can be used. Grape seed and chokeberry extracts have decreased blood pressure and lipid levels in small human trials. Other human investigations have shown the beneficial effects of cocoa, coffee, carob, and Momordica charantia. Thus far, most studies have involved a small number of subjects and have been of short duration. Future studies should be designed to account for a disease process in which the pathogenic factors may take place for years before disease manifestations take place, the possibly limited bioavailability of polyphenols, and the potential need to provide combinations or modifications of polyphenols.

Isolation and characterization of nicotiflorin obtained by enzymatic hydrolysis of two precursors in tea seed extract

Two flavonol triglycosides, camelliaside A (CamA) and camelliaside B (CamB), of tea seed extract (TSE) were subjected to enzymatic hydrolysis. Among five kinds of glycosidases investigated, beta-galactosidase (Gal) induced selective hydrolysis of CamA. On the other hand, pectinase (Pec) and cellulase (Cel) induced hydrolysis of CamB. For Gal and Pec, only kaempferol diglycoside (nicotiflorin, NF) was produced; on the other hand, significant amounts of kaempferol monoglycoside (astragalin, AS) and kaempferol (KR) were also detected for Cel. The combination of the use of Gal and Pec in the enzymatic hydrolysis of TSE afforded NF with high specificity. Crude NF with 22% purity was recovered from the enzymatic reaction mixture by extraction with organic solvent, and pure NF with >95% purity was obtained by crystallized in water. The chemical structure of NF was confirmed by (1)H and (13)C NMR analyses.

(-)-Ternatin inhibits adipogenesis and lipid metabolism in 3T3-L1 cells

(-)-Ternatin, a highly N-methylated cyclic peptide, inhibits fat accumulation in 3T3-L1 cells and reduces fat mass in mice. However, the mechanism for its anti-adipogenic effect has remained unknown. To examine the mechanism used by (-)-ternatin to inhibit adipocyte differentiation, we examined the effects of (-)-ternatin and [l-Ala(4)]ternatin, an inactive analog of (-)-ternatin, on the expression of adipocyte markers and lipogenic enzymes. We found that (-)-ternatin potently reduced mRNA expression of several adipocyte markers in a dose-dependent manner, whereas [l-Ala(4)]ternatin showed no effects. At the immediate early phase, (-)-ternatin, but not [l-Ala(4)]ternatin, reduced the expression of Srebp1c, Fas, Acc2 and C/EBP-alpha while showing no effects on C/EBP-beta and C/EBP-delta. These results suggest that (-)-ternatin affects the mid-to late differentiation stages of adipocytes. Consistent with the decreased expression of lipogenic enzymes, (-)-ternatin potently inhibited triglyceride synthesis. Intriguingly, (-)-ternatin also inhibited triglyceride synthesis in rat primary hepatocytes, suggesting that the potential action sites for (-)-ternatin are shared by adipocytes and liver. Although the target molecule of (-)-ternatin remains unknown, our data suggest that (-)-ternatin and its potential target might provide a new therapeutic approach to metabolic disorders.