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Fenugreek is a well known annual herb widely used in both medicine and food. Four flavonoid glycosides have been separated from fenugreek seeds in our previous study. In this study, the effects of the four flavonoid glycosides on regulating glycolipid metabolism and improving mitochondrial function were investigated. Isoorientin showed a very significant activity among these flavonoid glycosides. First, isoorientin decreased the accumulation of lipid droplets in 3T3-L1 preadipocytes by reducing the expression of adipokines including PPARγ, C/EBPα, and FAS. Second, isoorientin restored insulin-stimulated glucose uptake in dexamethasone-induced insulin-resistant 3T3-L1 adipocytes by reactivating Akt and AMPK. Finally, isoorientin improved mitochondrial dysfunction induced by dexamethasone in 3T3-L1 adipocytes. Isoorientin also reversed dexamethasone-induced decrease in mitochondrial membrane potential (MMP) and intracellular ATP production, reduced accumulation of intracellular reactive oxygen species (ROS), and protected mitochondrial DNA (mtDNA) from oxidative damage. At the same time, mitochondrial biogenesis is promoted. Therefore, isoorientin may be an attractive candidate as a glucose-lowering and insulin-resistance-improving agent for the treatment of diabetes.
<i>Potentilla parvifolia </i>Fisch. (Rosaceae) is a traditional medicinal plant in P. R. China. In this study, seven flavonoids, ayanin (<b>1</b>), tricin (<b>2</b>), quercetin (<b>3</b>), tiliroside (<b>4</b>), miquelianin (<b>5</b>), isoquercitrin (<b>6</b>), and astragalin (<b>7</b>), were separated and purified from ethyl acetate extractive fractions from ethanol extracts of <i>P. parvifolia</i> using a combination of sevaral chromatographic methods. The human neuroblastoma SH-SY5Y cells were differentiated with all trans-retinoic acid and treated with okadaic acid to induce tau protein phosphorylation and synaptic atrophy, which could establish an Alzheimer's disease cell model. The neuroprotective effects of these flavonoids in cellular were evaluated <i>in vitro</i> by this cell model. Results from the Western blot and morphology analysis suggested that compounds <b>3</b> and <b>4</b> had the better neuroprotective effects.
Obesity, a major health problem worldwide, is a complex multifactorial chronic disease that increases the risk for insulin resistance, type 2 diabetes, coronary heart disease, and hypertension. In this study, we assessed methods to isolate hypaphorine, a potent drug candidate for obesity and insulin resistance. Semi-preparative reversed-phase liquid chromatography (semi-preparative RPLC) was established as a method to separate three compounds, adenosine, l-tryptophan, and hypaphorine, from the crude extracts of <i>Caragana korshinskii </i>Kom. Due to its specific chemical structure, the effect of hypaphorine on differentiation and dexamethasone (DXM) induced insulin resistance of 3T3-L1 cells was investigated. The structures of the three compounds were confirmed by UV, ¹H-NMR, and <sup>13</sup>C-NMR analysis and compared with published data. The activity results indicated that hypaphorine prevented the differentiation of 3T3-L1 preadipocytes into adipocytes by down-regulating hormone-stimulated protein expression of peroxisome proliferator activated receptor <i>γ</i> (PPAR<i>γ</i>) and CCAAT/enhancer binding protein (C/EBP<i>α</i>), and their downstream targets, sterol regulatory element binding protein 1 c (SREBP1c) and fatty acid synthase (FAS). Hypaphorine also alleviated DXM-induced insulin resistance in differentiated 3T3-L1 adipocytes <i>via</i> increasing the phosphorylation level of Akt2, a key protein in the insulin signaling pathway. Taken together, we suggest that the method can be applied to large-scale extraction and large-quantity preparation of hypaphorine for treatment of obesity and insulin resistance.
Fenugreek (Trigonella foenum-graecum L.) is a well-known annual plant that is widely distributed worldwide and has possessed obvious hypoglycemic and hypercholesterolemia characteristics. In our previous study, three polyphenol stilbenes were separated from fenugreek seeds. Here, we investigated the effect of polyphenol stilbenes on adipogenesis and insulin resistance in 3T3-L1 adipocytes. Oil Red O staining and triglyceride assays showed that polyphenol stilbenes differently reduced lipid accumulation by suppressing the expression of adipocyte-specific proteins. In addition, polyphenol stilbenes improved the uptake of 2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose (2-NBDG) by promoting the phosphorylation of protein kinase B (AKT) and AMP-activated protein kinase (AMPK). In present studies, it was found that polyphenol stilbenes had the ability to scavenge reactive oxygen species (ROS). Results from adenosine triphosphate (ATP) production and mitochondrial membrane potentials suggested that mitochondria play a critical role in insulin resistance and related signaling activation, such as AKT and AMPK. Rhaponticin, one of the stilbenes from fenugreek, had the strongest activity among the three compounds in vitro. Future studies will focus on mitochondrial biogenesis and function.
Aims: <b>Nelumbo nucifera</b> (Gaertn.) leaves are used widely in modulating obesity in traditional Chinese medicine. Our previous work demonstrated that aporphine alkaloids from it increased the glucose consumption in mature 3T3-L1 adipocytes. However, the underlying mechanisms of this increase remain unclear. Here we investigated the modulating effects of pronuciferine and nuciferine on lipogenesis and glucose uptake in insulin resistant 3T3-L1 adipocytes <b>in vitro</b>.<br>Main methods: Insulin resistant 3T3-L1 mature adipocytes were induced with dexamethasone, 3-isobutyl-methylxanthine and insulin. The lipid droplets and the intracellular triglyceride contents in mature adipocytes were detected by Oil red O staining and colorimetry respectively. The glucose uptake was measured with a fluorescent deoxyglucose analog (2-NBDG). The glucose transporter type 4 (GLUT-4) expression was measured by fluorescent-immunohistochemistry and the activation of 5′-AMP-activated protein kinase (AMPK) was detected by its alpha subunit phosphorylation.<br>Key findings: Both nuciferine and pronuciferine treatments significantly decreased the lipid droplets and the intracellular triglyceride contents but increased the glucose uptake in the insulin resistant 3T3-L1 adipocytes. Furthermore, both pronuciferine and nuciferine showed the ability to up-regulate the expression of GLUT4, triggering the phosphorylation of AMPK in mature 3T3-L1 adipocytes, although pronuciferine exhibited a more powerful effect compared to nuciferine.<br>Significance: In summary, all the results demonstrate that pronuciferine and nuciferine ameliorate the glucose and lipid metabolism in insulin-resistant 3T3-L1 adipocytes, which might be due to the activation of the AMPK signaling pathway.
OBJECTIVES: To investigate the protective effect of Herpetospermum pedunculosum (H. pedunculosum) seed oil against carbon tetrachloride (CCl4)-induced liver damage.METHODS: This experimental study was conducted at the Northwest Institute of Plateau Biology, Chinese Academy of Sciences, and Yantai University, China from November 2012 to May 2013. The H. pedunculosum seed oil was extracted using supercritical carbon dioxide. The antioxidant activities of H. pedunculosum seed oil were assayed in vitro by 2,2-diphenyl-1-picrylhydrazyl assay, lipid peroxidation assay, and antihemolytic assay. Adult Sprague Dawley rats were randomly divided into 6 groups (10 rats/group) including control, CCl4, CCl4+bifendate, and CCl4+H. pedunculosum seed oil (3 different doses) groups. RESULTS: The CCl4-induced liver lesions include hepatocyte necrosis, ballooning degeneration, calcification, and fibrosis. Moreover, CCl4 damage results in an obvious increase of serum triglycerides, high-density lipoprotein, low-density lipoprotein, malondialdehyde, total bilirubin, alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase activity. In addition, CCl4 also significantly decreased the activities of superoxide dismutase (SOD). By contrast, H. pedunculosum seed oil administration significantly ameliorated the CCl4-induced liver lesions, lowered the serum levels of hepatic enzyme markers, and increased the activities of SOD. CONCLUSION: The results of this study show that H. pedunculosum seed oil can be proposed to protect the liver against CCl4-induced oxidative damage in rats, and the hepatoprotective effect might be correlated with its potent antioxidant and free radical scavenging effect.
Aporphine alkaloids from the leaves of Nelumbo nucifera Gaertn are substances of great interest because of their important pharmacological activities, particularly anti-diabetic, anti-obesity, anti-hyperlipidemic, anti-oxidant, and anti-HIV's activities. In order to produce large amounts of pure alkaloid for research purposes, a novel method using high-speed counter-current chromatography (HSCCC) was developed. Without any initial cleanup steps, four main aporphine alkaloids, including 2-hydroxy-1-methoxyaporphine, pronuciferine, nuciferine and roemerine were successfully purified from the crude extract by HSCCC in one step. The separation was performed with a simple two-phase solvent system composed of n-hexane-ethyl acetate-methanol-acetonitrile-water (5:3:3:2.5:5, v/v/v/v/v). In each operation, 100 mg crude extracts was separated and yielded 6.3 mg of 2-hydroxy-1-methoxyaporphine (95.1% purity), 1.1 mg of pronuciferine (96.8% purity), 8.5 mg of nuciferine (98.9% purity), and 2.7 mg of roemerine (97.4%) respectively. The chemical structure of four aporphine alkaloids are identified by means of electrospray ionization MS (ESI-MS) and nuclear magnetic resonance (NMR) analysis. Moreover, the effects of four separated aporphine alkaloids on insulin-stimulated glucose consumption were examined in 3T3-L1 adipocytes. The results showed that 2-hydroxy-1-methoxyaporphine and pronuciferine increased the glucose consumption significantly as rosiglitazone did.
Two novel organic amide alkaloids, 4-[(<i>E</i>)-<i>p</i>-coumaroylamino]butan-1-ol (<b>1</b>) and 4-[(<i>Z</i>)-<i>p</i>-coumaroylamino]butan-1-ol (<b>2</b>), together with a rare pyridoindole alkaloid, hippophamide (<b>3</b>), were isolated from the seed residue of <i>Hippophae rhamnoides</i> Linn. subsp. <i>sinensis</i> Rousi. Their structures were determined by spectroscopic means. The results show that compounds <b>1</b> and <b>2</b> are (<i>E</i>/<i>Z</i>)<i>-</i>isomers, compound <b>3</b>, a pyridoindole alkaloid concerted with <i>γ</i>-lactam ring.