The study of antioxidant activities of fucoidan from Laminaria japonica

Two large molecular weight fucoidan fractions F-A and F-B were obtained by water extraction and anion-exchange chromatography and then L-A and L-B with low molecular weight and uronic acid content were prepared by radical process degradation of F-A and F-B. The antioxidant activities of the fucoidan fractions on two oxygen free radicals and Cu2 -induced low-density lipoprotein (LDL) oxidation were studied. The results show that all the fucoidan fractions had excellent scavenging capacities on superoxide radical and hypochlorous acid, except the highly sulfated fraction L-B. In LDL oxidation system, low molecular weight fractions L-A and L-B exhibited great inhibitory effects on LDL oxidation induced by Cu2 , however F-A and F-B had little inhibitory effects in this system due to their large molecular weights. The present results suggest that fucoidan from Laminaria japonica is an excellent natural antioxidant and has great potential for preventing the free radical-mediated diseases.     

小肽转运载体的分子营养学的研究进展

目前动物体内的小肽转运载体发现的至少有五种,其中研究最为广泛的是PepT l和PepT 2。PepT 1和PepT 2都是依质子的寡肽转运载体(POT)家族的成员。PepT 1是低亲和力、高容量的肽载体,PepT 2是高亲和力、低容量的肽载体。PepT l主要在消化道中表达,在肾脏中也有微弱的表达:PepT 2主要在肾脏中表达。本文主要对小肽转运载体的组织分布、分子结构特征以及影响小肽转运载体转运的因素等方面的研究进展作一综述。     

青黛中靛玉红的提取及其抗氧化活性

利用超声波辅助乙酸乙酯提取青黛中靛玉红,考察提取物对羟基自由基的清除作用及对油脂氧化的抑制效果,并与柠檬酸和Vc作比较.用乙酸乙酯为提取剂,料液比为1∶10（g/mL）,在40 W超声功率、13 kHz超声频率及250 W加热功率的条件下超声50 min,提取率达到0.12%.提取物对羟基自由基有一定的清除作用,并呈现一定的量效关系,能增加植物油的抗氧化能力,相同条件下对油脂的抗氧化效果强于Vc、柠檬酸.     

野黄芩苷的密度泛函理论研究

采用密度泛函理论B3LYP方法在6.311G(d)基组上对野黄芩苷进行了理论计算,对其分子构型、偶极矩、疏水参数、红外光谱、酚羟基解离焓、自旋密度分布和前线轨道结构进行详细分析。结果表明,野黄芩苷是通过酚羟基发挥抗氧化作用的,其中,A环C6位置酚羟基活性最强,B环C4’酚羟基活性次之,A环C5酚羟基活性最弱。野黄芩苷在体内极性较大的环境下,可以达到好的吸收效果,研究结果为更有效合理地利用野黄芩苷提供了理论指导。     

黄瓜;多糖;自由基;清除;抗氧化性

建立了热水提取、乙醇沉淀、Sevage法除蛋白、有机溶剂分离精制提取黄瓜多糖的方法,并用蒽酮一硫酸比色法测定其含量;采用超氧阴离子自由基、羟基自由基、二苯代苦味肼基自由基(DPPH·)体系,对黄瓜多糖的抗氧化活性进行了研究,结果表明:黄瓜多糖对DPPH·、·OH and O2-·具有较强的清除能力,与其浓度呈线性关系.     

番茄红素对人体生理及运动机能的影响

番茄红素是一种天然类胡萝卜素,具有抗氧化、抗癌、调节血脂、提高免疫力等多种生理功能.通过对番茄红素成份结构的分析及在人体内作用机理的研究,发现其能有效地清除自由基,延缓运动性疲劳的发生,提高机体免疫功能.     

四种缩合试剂对含N-Me二肽的合成

用N,N′-二环己基碳二亚胺(DCC)/1-羟基-苯并-三氮唑(HOBt)、1-乙基-(3-二甲基氨基丙基)碳酰二亚胺(EDC)/HOBt、2-乙氧基-1-乙氧碳酰基-1,2-二氢喹啉(EEDQ)、3-(二乙氧基磷酰基)-氧-1,2,3-苯并三嗪-4(3H)-酮(DEPBT)4种常用缩合试剂合成了含N-Me二肽Boc-Leu-N-Me-Leu-OBzl,产率分别为73.5%～92.8%,65.2%～85.9%,38.9%,87.8%.比较发现反应物Boc-Leu-OH、H-N-Me-Leu-OBzl与缩合试剂DCC/HOBt的物质的量比在2.0:1.0:2.0时产率最高.利用此比例合成了3个立体异构体,产率较高.     

A novel method for thermodynamic study on binding of copper ion with Alzheimer’s amyliod β peptide

The interaction of Cu²⁺ with the first 16 residues of the Alzheimer's amyliod β peptide, Aβ (1-16), was studied by employing isothermal titration calorimetry at pH 7.2 and 37℃ in aqueous solution. The Gholamreza Rezaei Behbehani (GRB) solvation model was used to reproduce the enthalpies of Cu²⁺+ Aβ(1-16) interaction over the whole Cu²⁺ concentrations. The binding parameters recovered from the solvation model were attributed to the structural change of Aβ (1-16) due to the metal ion interaction. It was found that there is a set of two identical and non interacting binding sites for Cu²⁺ ions. The molar enthalpy of binding is ΔH=27.895 kJ/mol. The association binding constants are 1.895 μm^-1 and 1.891 μm^-1 for the first and second binding sites respectively.     

微波辅助下离子液体中肽核酸前体-碱基乙酸酯的合成

以离子液体为溶剂,在微波辐射下合成了合成肽核酸的重要原料,反应时间短,普适性好,收率较高,具有很高的区域选择性.产品经1H NMR,13C NMR表征.