Tae-Il Jeon

Quercetin Reduces High‐Fat Diet‐Induced Fat Accumulation in the Liver by Regulating Lipid Metabolism Genes

To understand the molecular mechanisms underlying the influence of quercetin on the physiological effects of hyperlipidemia, we investigated its role in the prevention of high‐fat diet (HFD)‐induced obesity and found that it regulated hepatic gene expression related to lipid metabolism. Quercetin supplementation in mice significantly reduced the HFD‐induced gains in body weight, liver weight, and white adipose tissue weight compared with the mice fed only with HFD. It also significantly reduced HFD‐induced increases in serum lipids, including cholesterol, triglyceride, and thiobarbituric acid‐reactive substance (TBARS). Consistent with the reduced liver weight and white adipose tissue weight, hepatic lipid accumulation and the size of lipid droplets in the epididymal fat pads were also reduced by quercetin supplementation. To further investigate how quercetin may reduce obesity, we analyzed lipid metabolism‐related genes in the liver. Quercetin supplementation altered expression profiles of several lipid metabolism‐related genes, including Fnta, Pon1, Pparg, Aldh1b1, Apoa4, Abcg5, Gpam, Acaca, Cd36, Fdft1, and Fasn, relative to those in HFD control mice. The expression patterns of these genes observed by quantitative reverse transcriptase‐polymerase chain reaction were confirmed by immunoblot assays. Collectively, our results indicate that quercetin prevents HFD‐induced obesity in C57B1/6 mice, and its anti‐obesity effects may be related to the regulation of lipogenesis at the level of transcription. Copyright

Coumaroyl quinic acid derivatives and flavonoids from immature pear ( Pyrus pyrifolia nakai) fruit

Fourteen compounds were isolated from 60% ethanol extracts of immature pear (Pyrus pyrifolia Nakai cv. Chuhwangbae) fruit using Amberlite XAD-2 column HPLC with guided DPPH radical scavenging assay. Based on MS and NMR analysis, the isolated compounds were identified as 5-O-trans-caffeoyl quinic acid methyl ester (1), malaxinic acid (2), 5-O-trans-p-coumaroyl quinic acid methyl ester (3), 5-O-cis-p-coumaroyl quinic acid methyl ester (4), 5-O-trans-p-coumaroyl quinic acid (5), trans-p-coumaric acid (6), methyl cis-p-coumarate (7), methyl trans-p-coumarate (8), 3,5-O-dicaffeoyl quinic acid (9), (-)-epicatechin (10), (S)-(+)-2-cis-abscisic acid (11), isorhamnetin 3-O-β-d-galacto-pyranoside (12), isorhamnetin-3-O-β-d-glucopyranoside (13), and isorhamnetin 3-O-α-l-rhamnopyranosyl (1→6)-O-β-d-glucopyranoside (14). Six compounds (1, 2, 6, 9, 10, and 13) were identified previously, but other compounds (3–5, 7, 8, 11, 12, and 14) were isolated for the first time from pear.

Fisetin protects against hepatosteatosis in mice by inhibiting miR‐378

SCOPE Lipid homeostasis in vertebrates is regulated at many levels including synthesis, degradation, and distribution. MicroRNAs (miRNAs) are key regulators of lipid homeostasis. The use of phytochemicals to target miRNA (miR) could provide new therapeutic approaches to human diseases. Thus, we investigated the regulation of lipid metabolism by the flavonoid fisetin during experimental analysis of hepatic miRs in mice. METHODS AND RESULTS Mice were separated into three groups. One group was maintained on the normal diet and the other two groups were fed either a high-fat (HF) diet or HF supplemented with fisetin. We found that fisetin lowered hepatic fat accumulation in HF mice and reversed abnormal expressions of lipid metabolism genes. The co-expression of miR-378 and its host gene PGC-1β was significantly induced by HF, whereas fisetin prevented the induction of both genes. We also identified nuclear respiratory factor-1 (NRF-1), a critical regulator of the mitochondrial function, as a direct target of miR-378. CONCLUSION Dietary fisetin protects against hepatosteatosis in association with modulation of lipid metabolism genes and miR-378 in mice. These observations suggest that the use of fisetin to target miRs could be an effective prevention or intervention against metabolic diseases.

Fisetin regulates obesity by targeting mTORC1 signaling

Fisetin, a flavonol present in vegetables and fruits, possesses antioxidative and anti-inflammatory properties. In this study, we have demonstrated that fisetin prevents diet-induced obesity through regulation of the signaling of mammalian target of rapamycin complex 1 (mTORC1), a central mediator of cellular growth, cellular proliferation and lipid biosynthesis. To evaluate whether fisetin regulates mTORC1 signaling, we investigated the phosphorylation and kinase activity of the 70-kDa ribosomal protein S6 kinase 1 (S6K1) and mTORC1 in 3T3-L1 preadipocytes. Fisetin treatment of preadipocytes reduced the phosphorylation of S6K1 and mTORC1 in a time- and concentration-dependent manner. To further our understanding of how fisetin negatively regulates mTORC1 signaling, we analyzed the phosphorylation of S6K1, mTOR and Akt in fisetin-treated TSC2-knockdown cells. The results suggested that fisetin treatment inhibits mTORC1 activity in an Akt-dependent manner. Recent studies have shown that adipocyte differentiation is dependent on mTORC1 activity. Fisetin treatment inhibited adipocyte differentiation, consistent with the negative effect of fisetin on mTOR. The inhibitory effect of fisetin on adipogenesis is dependent of mTOR activity, suggesting that fisetin inhibits adipogenesis and the accumulation of intracellular triglycerides during adipocyte differentiation by targeting mTORC1 signaling. Fisetin supplementation in mice fed a high-fat diet (HFD) significantly attenuated HFD-induced increases in body weight and white adipose tissue. We also observed that fisetin efficiently suppressed the phosphorylation of Akt, S6K1 and mTORC1 in adipose tissue. Collectively, these results suggest that inhibition of mTORC1 signaling by fisetin prevents adipocyte differentiation of 3T3-L1 preadipocytes and obesity in HFD-fed mice. Therefore, fisetin may be a useful phytochemical agent for attenuating diet-induced obesity.

Alpinia officinarum inhibits adipocyte differentiation and high-fat diet-induced obesity in mice through regulation of adipogenesis and lipogenesis.

Although Alpinia officinarum has been used in traditional medicine for the treatment of several conditions, such as abdominal pain, emesis, diarrhea, impaired renal function, and dysentery, little is known about its function in obesity. In this study, we investigated the antiobesity effect of A. officinarum ethanol extract (AOE) on lipid accumulation in 3T3-L1 cells and obesity in mice fed a high-fat diet (HFD). AOE dose-dependently suppressed lipid accumulation during differentiation of 3T3-L1 preadipocytes by downregulating CCAAT enhancer binding protein α (C/EBPα), sterol regulatory element binding protein-1 (SREBP-1), and peroxisome proliferator-activated receptor-γ (PPAR-γ) genes. Galangin, a major component of A. officinarum, had antiadipogenic effects in 3T3-L1 cells. AOE supplementation in mice fed a HFD revealed that AOE significantly decreased HFD-induced increases in body, liver, and white adipose tissue weights and decreased serum insulin and leptin levels. To elucidate the inhibitory mechanism of AOE in obesity, lipid metabolism-related genes were identified. AOE efficiently suppressed protein expressions of C/EBPα, fatty acid synthase, SREBP-1, and PPAR-γ in the liver and adipose tissue. The protein expression patterns, observed by immunoblot, were confirmed by quantitative real-time polymerase chain reaction. Collectively, these results suggest that AOE prevents obesity by suppressing adipogenic and lipogenic genes. AOE has potential for use as an antiobesity therapeutic agent that can function by regulating lipid metabolism.

miRNA and cholesterol homeostasis.

MicroRNAs (miRNAs) have recently emerged as a novel class of epigenetic regulators of gene expression. They are systemically involved in the control of lipid metabolism through a complex interactive mechanism that involves gene regulatory networks. Hence, they can contribute to defective lipid metabolism and metabolic diseases. Here, we review recent advances in the roles of lipid-sensing transcription factors in regulating miRNA gene networks, as well as miRNA expression and function in the regulation of cholesterol metabolism. This article is part of a Special Issue entitled: MicroRNAs and lipid/energy metabolism and related diseases edited by Carlos Fernández-Hernando and Yajaira Suárez.

Syzygium aromaticum ethanol extract reduces high-fat diet-induced obesity in mice through downregulation of adipogenic and lipogenic gene expression

Numerous medicinal plants and their derivatives have been reported to prevent obesity and related diseases. Although Syzygium aromaticum has traditionally been used as an anodyne, carminative and anthelmintic in Asian countries, its potential in the prevention and treatment of obesity has not yet been explored. Therefore, the present study investigated the anti-obesity effect of S. aromaticum ethanol extract (SAE) both in vitro and in vivo. To evaluate the anti-obesity potential of SAE in vitro, the effect of SAE treatment on adipocyte differentiation in 3T3-L1 cells was investigated. To evaluate its potential in vivo, mice were assigned to three groups: a group fed the American Institute of Nutrition AIN-76A diet (normal group), an experimental group fed a high-fat diet (HFD group) and an experimental group fed an HFD supplemented with 0.5% (w/w) SAE (HFD + SAE group). After 9 weeks of feeding, the body weight; white adipose tissue (WAT) mass; serum triglyceride (TG), total cholesterol (TC), high-density lipoprotein (HDL) cholesterol, glucose, insulin and leptin; hepatic lipid accumulation; and levels of lipid metabolism-related genes in the liver and WAT were measured. In vitro investigation of the effect of SAE treatment on 3T3-L1 cells revealed that it had efficiently inhibited the conversion of cells into adipocytes in a dose-dependent manner. In vivo investigation revealed that SAE supplementation had significantly decreased HFD-induced increases in the body weight, liver weight, WAT mass, and serum TG, TC, lipid, glucose, insulin and leptin levels. Consistent with its effects on liver weight and WAT mass, SAE supplementation was found to have suppressed the expression of lipid metabolism-related proteins, including SREBP-1, FAS, CD36 and PPARγ in the liver and WAT, in addition to downregulating mRNA levels of transcription factors including Srebp and Pparg. SAE inhibits fat accumulation in HFD-fed mice via the suppression of transcription factors integral to adipogenesis and lipogenesis, suggesting its potential in preventing obesity.

Identification of an anticancer compound against HT-29 cells from Phellinus linteus grown on germinated brown rice

OBJECTIVE To isolate and identify the anticancer compound against proliferation of human colon cancer cells from ethyl acetate (EtOAc) extract of Phellinus linteus grown on germinated brown rice (PB). METHODS EtOAc extract of PB was partitioned with n-hexane, EtOAc, and water-saturated n-butanol. Anticancer compound of n-hexane layer was isolated and identified by HPLC and NMR, respectively. Cytotoxicity against HT-29 cells was tested by SRB assay. RESULTS The n-hexane layer obtained after solvent fractionation of PB EtOAc extracts showed a potent anticancer activity against the HT-29 cell line. Atractylenolide I, a eudesmane-type sesquiterpene lactone, a major anticancer substance of PB, was isolated from the n-hexane layer by silica gel column chromatography and preparative-HPLC. This structure was elucidated by one- and two-dimensional NMR spectroscopic data. Atractylenolide I has not been reported in mushrooms or rice as of yet. The isolated compound dose-dependently inhibited the growth of HT-29 human colon cancer cells. CONCLUSIONS Atractylenolide I might contribute to the anticancer effect of PB.

Zinc-chelated Vitamin C Stimulates Adipogenesis of 3T3-L1 Cells

Adipose tissue development and function play a critical role in the regulation of energy balance, lipid metabolism, and the pathophysiology of metabolic syndromes. Although the effect of zinc ascorbate supplementation in diabetes or glycemic control is known in humans, the underlying mechanism is not well described. Here, we investigated the effect of a zinc-chelated vitamin C (ZnC) compound on the adipogenic differentiation of 3T3-L1 preadipocytes. Treatment with ZnC for 8 d significantly promoted adipogenesis, which was characterized by increased glycerol-3-phosphate dehydrogenase activity and intracellular lipid accumulation in 3T3-L1 cells. Meanwhile, ZnC induced a pronounced up-regulation of the expression of glucose transporter type 4 (GLUT4) and the adipocyte-specific gene adipocyte protein 2 (aP2). Analysis of mRNA and protein levels further showed that ZnC increased the sequential expression of peroxisome proliferator-activated receptor gamma (PPARγ) and CCAAT/enhancer-binding protein alpha (C/EBPα), the key transcription factors of adipogenesis. These results indicate that ZnC could promote adipogenesis through PPARγ and C/EBPα, which act synergistically for the expression of aP2 and GLUT4, leading to the generation of insulin-responsive adipocytes and can thereby be useful as a novel therapeutic agent for the management of diabetes and related metabolic disorders.

Chemical Conversion Pattern of Salvianolic Acid B in Aqueous Solution under Different Decoction Conditions

The chemical conversion pattern of salvianolic acid B (Sal B) in aqueous solution under different boiling conditions was compared. When the duration of boiling was varied, without varying temperature or pressure, the content of chemically converted compounds (CCCs) was mostly increased over time. In addition, under different conditions of temperature and pressure with the same boiling time, the content of a few compounds increased with increasing temperature and pressure. These results confirmed that high temperatures and pressures in boiling alter the final composition of CCCs of Sal B. Therefore, it was suggested that the boiling conditions (time, temperature, and pressure) may be responsible for alteration of biological activities of the compounds. Our investigation of the chemical conversion of compounds contained in foods and medicinal herbs may provide important information in clarifying the biological activity of Sal B containing foods and medicinal herbs.