荭草素抑制3T3-L1前脂肪细胞分化及其改善胰岛素抵抗的作用研究

目的研究荭草素对3T3-L1前脂肪细胞分化及对脂肪细胞胰岛素抵抗的影响,并探讨其作用机制。方法传统鸡尾酒法诱导分化3T3-L1前脂肪细胞,MTT法检测荭草素对前脂肪细胞活力的影响,油红O染色法检测脂质积累,酶法检测细胞内甘油三酯(triglyceride,TG)的含量。地塞米松诱导成熟的脂肪细胞,建立胰岛素抵抗模型,荧光标记2-脱氧葡萄糖(2-[N-(7-nitrobenz-2-oxa-1,3-diaxol-4-yl)amino]-2-deoxyglucose,2-NBDG)摄入法观察脂肪细胞对葡萄糖的摄取能力;Western blot检测腺苷酸活化蛋白激酶(adenosine monophosphate activated protein kinase,AMPK)、乙酰辅酶A羧化酶(acetyl Co A carboxylase,ACC)的磷酸化水平及葡萄糖转运体4(glucose transporter type 4,GLUT4)的表达水平,免疫荧光法检测GLUT4的向膜转位能力。结果荭草素可浓度依赖性地减少细胞脂滴的积累及细胞内TG的含量,但对细胞活力无明显的影响(P>0.05)。胰岛素抵抗状态下,荭草素明显增加脂肪细胞对2-NBDG的摄取(P<0.05),明显上调AMPK、ACC的磷酸化水平(P<0.05),促进GLUT4的向膜转位及表达。结论荭草素抑制前脂肪细胞的分化,同时,荭草素通过上调AMPK/GLUT4信号途径相关蛋白的表达,促进了细胞对葡萄糖的摄取,达到改善胰岛素抵抗的作用。     

HDL对3T3-L1细胞葡萄糖转运的影响及其机制研究

目的探讨HDL对3T3-L1细胞葡萄糖转运的影响及其机制。方法通过对3T3-L1成纤维细胞的分化,培养符合实验要求的3T3-L1脂肪细胞。通过葡萄糖消耗实验和~3H标记的2-脱氧葡萄糖的摄取实验,研究HDL对葡萄糖转运的影响,应用RT-PCR和Western blot探讨其机制。结果 HDL可以促进3T3-L1脂肪细胞对葡萄糖的转运和摄取。3T3-L1脂肪细胞对葡萄糖的转运和摄取过程中,蛋白在RNA转录水平上没有增加,而是发生了AKT、AMPK蛋白的磷酸化。结论 HDL促进3T3-L1脂肪细胞对葡萄糖的摄取是通过AKT和AMPK两种途径来实现的。     

褪黑素改善胰岛素抵抗3T3-L1脂肪细胞葡萄糖的摄取

目的研究褪黑素对游离脂肪酸(FFA)诱导的胰岛素抵抗3T3-L1脂肪细胞葡萄糖摄取能力的影响。方法 "鸡尾酒"法培养诱导3T3-L1成纤维细胞分化成脂肪细胞,油红O染色鉴定脂肪细胞形态;利用棕榈酸(300μmol/L)诱导脂肪细胞的胰岛素抵抗,采用液体闪烁法检测细胞葡萄糖摄取能力;检测褪黑素对FFA处理的3T3-L1脂肪细胞的葡萄糖摄取能力的影响。结果 3T3-L1细胞经诱导分化成脂肪细胞,油红O染色呈圆形,脂滴呈典型的"戒环样"形态;用FFA处理上述细胞6 h后,细胞的葡萄糖摄取能力明显降低;褪黑素可以促进FFA处理的3T3-L1脂肪细胞胰岛素介导的葡萄糖摄取。结论 FFA可以降低胰岛素诱导的体外培养的脂肪细胞葡萄糖摄取能力,可能是胰岛素抵抗的病因之一。褪黑素可以干预FFA的作用,增加细胞的葡萄糖摄取能力。     

大黄素激活AMPK、PPARγ对3T3-L1脂肪细胞葡萄糖摄取的影响

目的研究大黄素对3T3-L1脂肪细胞葡萄糖摄取的影响,并探讨其作用机制。方法诱导分化成熟的3T3-L1脂肪细胞经LPS干预后分为Control组、大黄素给药组(1、10、50μmol·L~(-1)),检测6-NBDG摄取情况及GLUT4、PPARγ、AMPKα1/2、p-AMPKα1/2、IRS-1、p-IRS-1、Adiponectin、chREBP-α和chREBP-β的表达。用AMPK和PPARγ抑制剂分别干预后,检测6-NBDG的摄取情况。同时,以STZ诱导大鼠2型糖尿病模型,分为Control组和大黄素给药组,检测大鼠内脏脂肪组织的Adiponectin的mRNA表达及GLUT4、AMPKα1/2、p-AMPKα1/2蛋白表达。结果与Control组相比,大黄素可促进GLUT4、Adiponectin、chREBP-α、chREBP-β的mRNA表达及GLUT4、PPARγ、IRS-1、p-IRS-1、AMPKα1/2和p-AMPKα1/2的蛋白表达(P<0.05),可提高3T3-L1脂肪细胞对6-NBDG的摄取,经AMPK及PPARγ抑制剂分别干预后,大黄素对6-NBDG的摄取降低(P<0.05)。同时,大黄素可促进T2DM大鼠内脏脂肪组织Adiponectin的mRNA表达及GLUT4、AMPKα1/2和p-AMPKα1/2的蛋白表达(P<0.05)。结论大黄素可促进3T3-L1脂肪细胞的葡萄糖摄取功能,其作用机制与激活Adiponectin及IRS-1,进而激活AMPK和PPARγ的信号通路有关。     

西红花酸对3T3-L1前脂细胞增殖和分化的影响

目的：观察西红花酸对3T3-L1前脂细胞增殖分化的影响,并探讨其影响3T3-L1细胞分化的可能作用机制。方法：培养前脂肪细胞3T3-L1,四甲基偶氮唑盐（MTT）法检测西红花酸对其生长活性和增殖的影响;油红O染色和染色比色法分析脂肪细胞的分化程度;逆转录多聚酶联反应（RT-PCR）检测腺苷酸激活蛋白激酶（AMP-activated protein kinase,AMPK）mRNA的表达;Western blot法检测p-AMPK蛋白表达水平。结果：西红花酸高、中剂量（10-5、10-6mol/L）组均可以显著抑制前脂细胞的增殖和分化（P〈0.01）,而低剂量组（10-7mol/L）也可以抑制其增殖、分化（P〈0.05）;各剂量的西红花酸都能够增加AMPK的mRNA的表达、提高p-AMPK蛋白表达水平（P〈0.05）。结论：西红花酸具有抑制前脂细胞增殖分化的作用,可能和增强AMPK的表达有关。     

黄连素对衣霉素诱导的3T3-L1脂肪细胞胰岛素抵抗的影响

目的 探讨黄连素对内质网应激(ERS)诱导剂衣霉素诱导的3T3-L1脂肪细胞胰岛素抵抗(IR)的影响及可能机制.方法 体外诱导分化成熟的3T3-L1细胞,分别用衣霉素和黄连素干预.采用MTT法检测细胞生存率,葡萄糖氧化酶法检测3T3-L1细胞的葡萄糖消耗量,Western blot法检测3T3-L1细胞不同干预条件下ERS信号标志蛋白蛋白激酶R样内质网激酶(PERK)、磷酸化PERK(p-PERK)、真核生物翻译起始因子2α亚基(eIF2α)和磷酸化eIF2α (p-eIF2α)的表达.结果 胰岛素刺激的3T3-L1细胞葡萄糖消耗量可因衣霉素5 mg/L作用5h后减少(P＜0.05);黄连素20 μmol/L预处理24 h可拮抗衣霉素诱导的3T3-L1细胞的IR(P＜0.05).衣霉素5 mg/L作用5h后,p-PERK和p-eIF2α蛋白表达增加(P＜0.05);而黄连素预处理24h可降低衣霉素诱导的p-PERK和p-eIF2α蛋白表达(P＜0.05).结论 黄连素可改善ERS引起的3T3-L1细胞IR,其机制可能与其抑制PERK/eIF2α通路的激活有关.     

二氢杨梅素对胰岛素抵抗3T3-L1脂肪细胞的改善作用及其机制研究

目的研究二氢杨梅素(dihydromyricetin,DMY)对3T3-L1脂肪细胞胰岛素抵抗的改善作用及其机制。方法采用地塞米松诱导3T3-L1脂肪细胞形成胰岛素抵抗细胞,以1×10-6mol·L-1罗格列酮为阳性对照,DMY(1×10-5¹×10-8mol·L-1)与胰岛素抵抗3T3-L1脂肪细胞共培养72 h,用葡萄糖氧化酶法测定细胞培养基中的葡萄糖含量,计算葡萄糖消耗量;采用RT-PCR检测脂肪细胞的GLUT4、Akt 2和脂联素基因的表达量。DMY(1×10-51×10-8mol·L-1)与胰岛素抵抗3T3-L1脂肪细胞共培养72 h,用葡萄糖氧化酶法测定细胞培养基中的葡萄糖含量,计算葡萄糖消耗量;采用RT-PCR检测脂肪细胞的GLUT4、Akt 2和脂联素基因的表达量。DMY(1×10-5¹×10-8mol·L-1)加入正常3T3-L1脂肪细胞中培养48 h,检测细胞的葡萄糖消耗量。结果 DMY(5×10-71×10-8mol·L-1)加入正常3T3-L1脂肪细胞中培养48 h,检测细胞的葡萄糖消耗量。结果 DMY(5×10-7¹×10-8mol·L-1)明显增加地塞米松诱导胰岛素抵抗3T3-L1脂肪细胞的葡萄糖消耗量,并呈现一定的浓度依赖性,和罗格列酮相比,差异无统计学意义。1×10-51×10-8mol·L-1)明显增加地塞米松诱导胰岛素抵抗3T3-L1脂肪细胞的葡萄糖消耗量,并呈现一定的浓度依赖性,和罗格列酮相比,差异无统计学意义。1×10-5¹×10-8mol·L-1DMY处理正常3T3-L1脂肪细胞48 h后,葡萄糖消耗量与正常组相比差异无统计学意义。RT-PCR结果显示,DMY作用于胰岛素抵抗的脂肪细胞72 h后,脂肪细胞的GLUT4、Akt2和脂联素基因的表达量明显增加,与地塞米松模型组相比,差异有统计学意义。结论 DMY能改善3T3-L1脂肪细胞的胰岛素抵抗状态,其机制可能与其上调GLUT4、Akt2和脂联素基因的表达量有关。     

川续断皂苷Ⅵ对3T3-L1细胞的增殖和分化影响

目的研究川续断皂苷Ⅵ(asperosaponinⅥ,ASAⅥ)对3T3-L1前脂肪细胞的增殖及成脂分化影响,以进一步了解其药理作用。方法以3T3-L1前脂肪细胞为靶细胞,通过噻唑蓝(MTT)法观察不同浓度川续断皂苷Ⅵ对3T3-L1细胞增殖能力的影响;不同浓度(0、10、25、50μmol·L-1)川续断皂苷Ⅵ干预3T3-L1细胞的成脂诱导分化,油红O染色检测3T3-L1细胞分化程度;试剂盒测定各组培养液中葡萄糖及游离脂肪酸含量;荧光定量PCR(Q-PCR)检测过氧化物酶体增殖物激活受体γ(peroxisome proliferator-activatedreceptorγ,PPARγ)、CCAAT增强子结合蛋白(CCAAT/enhan-cer-binding proteinα,C/EBPα)mRNA表达水平。结果 MTT法测定表明不同浓度川续断皂苷Ⅵ对3T3-L1细胞增殖能力的影响不同,其中10μmol·L-1浓度组作用24 h后促增殖作用最明显,随着川续断皂苷Ⅵ浓度增加,促增殖效应降低;川续断皂苷Ⅵ能够剂量依赖性的抑制3T3-L1细胞成脂,减少细胞内脂滴聚集,抑制细胞对葡萄糖的吸收利用,减少游离脂肪酸形成,下调成脂过程中PPARγ和C/EBPαmRNA表达。结论川续断皂苷Ⅵ具有促进3T3-L1细胞增殖作用,并通过下调PPARγ和C/EBPα基因抑制3T3-L1细胞成脂分化。     

三黄汤对3T3-L1脂肪细胞糖脂代谢的影响

目的研究三黄汤(SHD)对胰岛素抵抗3T3-L1脂肪细胞糖脂代谢的作用及可能的调控机制。方法高糖高胰岛素(含地塞米松)诱导3T3-L1脂肪细胞发生胰岛素抵抗,给予对照药物罗格列酮(Ros)或不同浓度SHD干预24 h,检测培养上清中葡萄糖减少(消耗)量、甘油和游离脂肪酸(NEFA)浓度以及细胞内甘油三酯(TG)含量;以2-脱氧-[3H]-葡萄糖摄入法观察脂肪细胞对葡萄糖的转运率;应用反转录-聚合酶链反应(RT-PCR)检测葡萄糖转运体4(GLUT-4)的mRNA表达水平,以Western blot检测GLUT-4蛋白的表达水平。结果与对照组相比,SHD的中高剂量(5、10、20、40 g·L~(-1))能使胰岛素抵抗脂肪细胞的葡萄糖消耗量和葡萄糖的转运率增加(P<0.01)、脂肪细胞内TG降低(P<0.01),细胞上清液中甘油的浓度不同程度增加(P<0.01),并明显减少NEFA的溢出,以上变化在三黄汤5~20g·L~(-1)范围内呈现量效关系;同时,Ros增加葡萄糖消耗、葡萄糖的转运率和细胞内TG积累(P<0.01),对培养上清中甘油、NEFA无明显影响(P>0.05)。SHD中、高剂量与Ros都能不同程度明显上调GLUT-4的mRNA和蛋白表达水平(P<0.01)。结论 SHD能明显增加3T3-L1脂肪细胞的葡萄糖摄取和消耗,促进细胞内TG分解,并减少NEFA溢出,通过调节糖代谢和脂代谢改善胰岛素抵抗。     

吡啶羧酸铬通过AMPK信号通路促进3T3-L1脂肪细胞脂肪酸转位酶CD36的转位

目的研究吡啶羧酸铬(CrPic)对3T3-L1脂肪细胞脂肪酸转位酶CD36转位的作用及机制。方法采用3T3-L1脂肪细胞作为模型,通过免疫荧光及Western blot等方法观察CrPic及胰岛素对CD36转位的作用;并在此基础上,探讨CrPic对CD36作用的分子机制。结果免疫荧光结果显示CrPic和胰岛素可促进3T3-L1脂肪细胞的CD36从胞质转位到胞膜;Western blot结果表明脂肪细胞胞膜上CD36的含量也增多。给予腺苷酸活化蛋白激酶(AMPK)通路抑制剂compound C之后,CrPic促进CD36转位的作用消失,但胰岛素的作用却不受影响。结论 CrPic通过AMPK信号通路促进3T3-L1脂肪酸转位酶CD36的转位。     

3',3'-Difluoro-3'-deoxythymidine: comparison of anti-HIV activity to 3'-fluoro-3'-deoxythymidine.

3',3'-Difluoro-3'-deoxythymidine (3) has been synthesized in four steps from thymidine, and characterized by 1H NMR and NOE experiments. The JHF coupling constants support a conformation in solution that is predominantly 2'-endo (S). Although conformationally and sterically nucleoside 3 may resemble other thymidine analogs which are active against HIV-1, 3 is virtually inactive.     

3-二甲胺基-3-苯基丙醇的制备

苯甲醛和丙二酸经Knoevenagel缩合、NaBH4-I2体系还原得3-氨基-3-苯基丙醇，再经Eschweiler-Clark反应制得3-二甲胺基-3-苯基丙醇，总收率29％。     

Analysis of γβ, βγ, γγ, ββ multiple turns in proteins

Abstract: The number of γ‐turns in a representative protein dataset selected from the current Protein Data Bank has increased almost seven times during the past decade. Eighty percent classic γ‐turns and 57% inverse γ‐turns are associated as multiple turns with either another γ‐turn or a β‐turn. We refer to these as multiple turns of the (γβ)_1,2,3 or (βγ)_1,2,3 type, depending upon whether the γ‐turn is before or after the β‐turn along the protein chain, respectively. However, for multiple turns involving only γ‐turns, we follow the nomenclature analogous to that proposed earlier for the multiple (or double) β‐turns. Fifty‐eight per cent β‐turns are associated as multiple turns with another β‐turn. We extracted multiple turns from the protein dataset and classified them on the basis of individual γ‐ or β‐turn types and the number of overlapping residues. Furthermore, we evaluated the amino acid positional potentials and determined the statistically significant amino acid preferences, hydrogen bond/side‐chain interaction preferences in the multiple turns and secondary structure preferences for residues immediately flanking these turns. The results of our analysis would be useful in the modeling, prediction or design of multiple turns in proteins. The amino acid sequence corresponding to the multiple turn, position in the protein chain, PDB Code/chain in which multiple turn is present and the individual turn types constituting the multiple turns are available from our website and this information would also be integrated in our Database of Structural Motifs in Proteins ( http://www.cdfd.org.in/dsmp.html ).     

Analysis of γβ, βγ, γγ, ββ continuous turns in proteins

Abstract: We report the observation of continuous turns in proteins which comprise individual γ‐turns or β‐turns or both that are situated immediately one after the other along the polypeptide chain. The continuous turns were identified from a representative data set of three‐dimensional protein crystal structures. The γβ/βγ, γγ and ββ continuous turns represent peptides of varying amino acid residue lengths and conformations. The continuous turns frequently observed in proteins were: γβ, between a coil and a strand; βγ, between a helix and a strand; γγ, between coils; and ββ, either between a strand and a coil or between strands or coils. We determined the statistically significant amino acid residue preferences at individual positions in the turn, calculated amino acid positional potentials and analyzed main chain hydrogen bonds and side‐chain interactions likely to stabilize the continuous turns. The data on continuous turns have been integrated in the database of structural motifs in proteins (DSMP) on our web server at ( http://www.cdfd.org.in/dsmp.html ). This is useful to make queries on sequences compatible with different continuous turns.     

Synthese von γ,γ'-Dihydroxysulfonen und γ-Hydroxy-γ'-ketosulfonen

Syntheses of γ,γ'-Dihydroxysulfones and γ-Hydroxy-γ'-ketosulfones Reduction of γ,γ'-diketosulfones 1 with dimethylaminoborane leads to γ,γ'-dihydroxysulfones 3 via γ-hydroxy-γ'-ketosulfones 2 . The influence of substituents on the ratio of the yields of 2 and 3 is investigated.     

Mutagenicity of 3-nitrodibenzofuran and 3-aminodibenzofuran

Mutagenicities of 3-nitrodibenzofuran and 3-aminodibenzofuran were examined using Salmonella typhimurium TA98 and TA100. Strong mutagenicity was found in both compounds. The mutagenic potency of 3-nitrodibenzofuran was approximately 3.5-fold stronger in TA98 and twice stronger in TA100 than that of benzo[a]pyrene. Mutagenicity of 3-aminodibenzofuran was observed under metabolic activation and was 10 times stronger in TA98 and about 5 times stronger in TA100 than that of benzo[a]pyrene.