日本落叶松凋落针叶总黄酮的提取工艺及抗氧化活性研究

为促进日本落叶松废弃物的再利用,本研究以日本落叶松凋落针叶为原料,利用超声辅助浸提法对总黄酮提取工艺进行优化,并对其抗氧化活性进行初步研究.通过三因素三水平响应面分析,得到日本落叶松凋落针叶总黄酮提取的最佳工艺为:乙醇浓度60%、液料比33∶1 mL/g、提取温度80℃、超声功率270 W、超声频率40 kHz、提取时间58 min.总黄酮不同萃取相表现出不同程度的体外抗氧化活性,从大到小依次为正丁醇相水余相乙酸乙酯相石油醚相,其中正丁醇对DPPH自由基的半抑制率IC_(50)值为7.438μg/mL,略弱于维生素C(7.259μg/mL);清除ABTS自由基的IC_(50)值为6.425μg/mL,表现出了比维生素C更高的清除能力.该提取工艺稳定可行,总黄酮得率高,抗氧化活性较好.研究结果表明日本落叶松废弃物有开发成植物源的天然抗氧化剂的潜力.     

Enhanced urease inhibition activity of Ag nanomaterials capped with N-substituted methyl 5-acetamido-β-resorcylate

Medically, bacterial ureases are important virulent factors and are used for treatment of peptic ulcers and urinary tones. Reported urease inhibitors are associated with various side effects including antibiotic resistance as a major one. Still there is an urgent need to synthesize new urease inhibitors. In this context we have synthesized new urease inhibitor i.e. AgL that is composed of Ag nanomaterials capped with N-substituted methyl 5-acetamido-β-resorcylate(L). The conjugation of L to silver was confirmed through FTIR, UV–vis and TEM analysis.Bare silver nanomaterials(Ag) were also prepared. The stability of AgL nanostructures was determined against various parameters(temperature, high salt concentration, pH) and found to be stable. The in vitro antimicrobial(antibacterial, antifungal), enzyme inhibition(xanthine oxidase, urease, carbonic anhydrase, α-chymotrypsin,cholinesterase) and antioxidant activities of AgL were investigated and compared with Ag, L and standard drugs.In comparison to other bioactivities, AgL shows statistically enhanced selective enzyme inhibition activity against urease enzyme. Urease inhibition activity of AgL was significantly greater than standard drug(thiourea),L and Ag. On a per weight basis, AgL required about 11–18 times less amount of L for inhibition of urease enzyme.     

异丙苯裂解反应中Ti-ZSM-5分子筛的活性衰减与积炭

用异丙苯裂解反应考察了Ti-ZSM-5分子筛的催化活性,发现裂解活性与Ti-ZSM-5中Si/Ti有关,Ti进入分子筛骨架降低了积炭活性,但焦炭的生成并不影响稳态活性,表明炭主要沉积在催化剂的外表面上。     

钛铁矿制备的SO_4~（2－）／TiO_2型固体超强酸在酯化反应中的催化活性

以钛铁矿为原料制备了ＳＯ４２－／ＴｉＯ２固体超强酸型他化剂，结果表明其在乙酸和乙醇酯化反应中具有明显的催化活性。     

醌氢醌玻碳修饰电极的性能研究与应用

本文详细地研究了醌氢醌玻碳修饰电极的催化活性以及用该电极测定抗坏血酸的条件,测定结果非常理想。     

铬-铈氧化物的催化活性和掺碱(土)元素的影响

研究了Cr-Ce二元氧化物催化剂对甲苯完全氧化的性能,以及掺碱(±)金属元素对其活性的影响。实验表明Cr/Cr Ce(原子比)在0.5—0.7时,催化剂有最佳活性。碱(±)金属元素的掺加,改善了Cr-Ce体系对甲苯完全氧化反应的活性,并随掺入元素的碱性增大而提高。其中以钾的掺入效果最优,钾含量的增加,氧化活性随之提高,在K/Cr Ce(原子比)=0.05—0.10时最佳,再增大钾的含量,无益于催化剂活性的改善。     

The effects of temperature on ATPase activity and force generation in skinned muscle fibers from the Pacific blue marlin (Makaira nigricans)

Summary ATPase activity and force generation have been measured simultaneously in isolated, demembranated muscle fibers of the Pacific blue marlin (Makaira nigricans) between 0 and 30°C. Tension generation is relatively independent of temperature above 15°C and falls with a Q₁₀ of <1.5 on decreasing the temperature to 0°C. In contrast, the Q₁₀ for ATPase activity is 2.2 over the range 0–30°C. The results are interpreted in terms of the cross bridge theory of contraction.     

Both thermal and nociceptive afferents influence the unit activity of the neurons in the corpus striatum

Summary Both thermal and nociceptive stimulation in the periphery were shown to influence the neuronal activity recorded in the striatal area. Both the thermal and nociceptive sensitivity of the striatal neurons were closely related.The authors are grateful to the Alexander von Humboldt-Stiftung (Bad Godesberg, Bonn, Federal Republic of Germany) for donations of the necessary equipment for the present study. The research reported here was supported by grants from the National Science Council (Taipei, Taiwan, Republic of China)     

重组牛肠激酶轻链在大肠杆菌中的表达和纯化

密码子优化全基因合成了牛肠激酶轻链基因(sBEKLC),采用pET-39b( )构建了融合表达载体,在大肠杆菌中进行了成功表达.37℃在含30 mg/L卡那霉素的LB培养基中培养,当细胞密度(D600)达到0.5时,降低温度到28℃,加入终浓度为0.1 mM的异丙基硫代-βD-硫代半乳糖苷诱导外源蛋白表达,继续培养6 h后收集菌体,融合蛋白(DsbA-sBEKLC)产量达到151.2mg/L,相当于80.6 mg/L sBEKLC.使用渗透冲击技术从细胞周质中提取sBEKLC,经过亲和层析可从每升发酵液中得到6.8 mg sBEKLC,经检测sBEKLC具有生物活性.     

Is the ubiquitin-proteasome system impaired in Huntington’s disease?

Ubiquitylated inclusion bodies (IBs) found in Huntington’s disease (HD) postulate an impaired ubiquitin-proteasome system. However, this hypothesis remains controversial. In vitro-generated polyglutamine aggregates failed to inhibit purified proteasomes, while filamentous huntingtin aggregates isolated from mice resulted in inhibition. However, similarly isolated IBs did not, thus suggesting that IB formation is protective by sequestering smaller inhibitory aggregates. Accordingly, proteasome-activity assays in IB-containing mouse brain homogenates did not show decreased activity. On the contrary, some of the endoproteolytic proteasome activities increased, probably due to altered subunit composition. However, activity was found decreased in postmortem human HD tissue. Finally, evidence supporting the hypothesis was found in HD cell models expressing fluorescent ubiquitin-proteasome system reporters but not in retina of SCA-7 mice with similar reporters. In summary, it seems that mutant huntingtin, probably in intermediate aggregate forms, has the potential to inhibit proteasome activity, but the global status of the system in HD brain tissue is not yet fully elucidated.