抗氧化剂α-硫辛酸的生物合成研究进展

α-硫辛酸及其还原态二氢硫辛酸具有极强的抗氧化性,可改善葡萄糖代谢,减弱氧化应激,对糖尿病性白内障、糖尿病多发性神经病及心血管损伤等糖尿病并发症具有较好的预防和治疗作用。概述了α-硫辛酸的作用机制、生物合成途径及应用,重点综述了具有良好应用前景的生物法生产α-硫辛酸工艺。     

Preparation and characterization of SLNs (W/O/W type) contained lipoic acid PEG ester by variation lipid

This study describes a nanoparticle preparation method using SLNs (solid lipid nanoparticles: W/O/W type). Classical methods have high encapsulation efficiency for hydrophobic drugs but have low encapsulation efficiency (2–3%) for hydrophilic drugs. The preparation of SLNs that has a far higher skin penetration effect compared with general liposomes is proposed in this study. An additional aim is to also maximally increase encapsulation efficiency of hydrophilic drugs. The SLNs preparation method described here used coconut oil, jojoba oil and macadamia oil that are resistant to degradation by microorganisms and are usable emulsifiers due to their physical properties imparted by their fatty acid composition. The results indicate that SLNs containing coconut oil had the highest encapsulation efficiency and also the smallest average particle size (270 nm). The largest particle size was produced by macadamia oil and 1% Tween 60. The fastest release of contents resulted from SLNs made of coconut oil and 2% Tween 60, while the slowest release was from SLNs made of macadamia oil and 2% Tween 20.     

新型硫酯类抗氧剂的合成及性能

以硫代二甘醇和硬脂酸为原料,选用对甲苯磺酸为催化剂,二甲苯为带水剂,合成了新型抗氧剂硫代二甘醇二硬脂酸酯。通过正交实验得到最佳工艺条件为：反应温度160～170 ℃、醇酸摩尔比为2∶1、催化剂用量为反应原料总质量1.0%、带水剂用量为15 mL,在此工艺条件下硫代二甘醇二硬脂酸酯的产率可达94.2％。用红外光谱和质谱对产品结构进行了表征。将该产品应用于聚丙烯中,熔体流动速率、拉伸强度、断裂伸长率和冲击强度测试结果表明其具有良好的抗氧作用。     

防老剂FR的合成研究

在强酸性树脂催化剂存在下,以苯胺和丙酮为原料合成了防老剂FR。考察了催化剂种类、缩聚反应时间、反应温度以及丙酮中水质量分数对合成防老剂FR的影响,探索出最佳的反应条件:以强酸性阳离子交换树脂作为缩合反应的催化剂,缩合反应温度为130℃,反应时间为10 h,聚合反应温度为90～100℃,反应时间为6 h。用高效液相色谱对成品防老剂FR的组成进行表征,产品中二、三、四聚体总质量分数为83.18%。     

Effects of conjugated linoleic acids on protein to fat proportions,fatty acids,and plasma lipids in broilers

In a performance trial, broiler chickens received 29 g per kg feed of a preparation containing 70% linoleic acid (LA) in the control treatment and another preparation containing approximately the same amount of conjugated linoleic acids (CLA) in the experimental treatment. Diets of CLA treatment contained 18 g CLA per kg feed. The CLA preparation contained the isomers cis‐9,trans‐11 and trans‐10,cis‐12 at a proportion 1:1, other CLA isomers were quantitively negligible. Performance parameters (weight gain and feed conversion ratio over a 42 day period) were not significantly influenced by CLA intake. However, fat content of liver, breast, and leg muscles was reduced and protein contents in liver and leg muscles were elevated significantly. Fat to protein ratios in the main edible parts were shifted in favour of protein in CLA treated animals. In all analysed tissue lipids the content of saturated fatty acids was increased and that of monounsaturated fatty acids was decreased significantly. At the same time CLA was incorporated in tissue lipids effectively reaching more than 10 g per 100 g of total fatty acids. With regard to isomers the cis‐9,trans‐11 isomer was found in higher concentrations in tissue lipid fractions compared to the trans‐10,cis‐12 isomer. It was concluded that nutrient repartitioning due to CLA intake described for other species is also valid for broilers. Using appropriate feeding strategies it is possible to produce CLA enriched food from broilers.     

抗氧剂对PVC-U异型材焊接强度的影响

热稳定剂是PVC-U异型材配方中最为重要的一种组分,它能提高PVC-U在加工和应用过程中的热稳定性和耐候性,但是仅有热稳定剂并不能完全满足PVC-U异型材在整个加工和使用过程中的要求.以铅系稳定剂为例,在PVC-U异型材配方中添加适当的抗氧剂,能有效地改善和提高PVC-U异型材的焊接强度.     

Effect of freeze-drying on the antioxidant compounds and antioxidant activity of selected tropical fruits

The effects of freeze-drying on antioxidant compounds and antioxidant activity of five tropical fruits, namely starfruit (Averrhoa carambola L.), mango (Mangifera indica L.), papaya (Carica papaya L.), muskmelon (Cucumis melo L.), and watermelon Citruluss lanatus (Thunb.) were investigated. Significant (p < 0.05) differences, for the amounts of total phenolic compounds (TPC), were found between the fresh and freeze-dried fruit samples, except muskmelon. There was no significant (p > 0.05) change, however, observed in the ascorbic acid content of the fresh and freeze-dried fruits. Similarly, freeze-drying did not exert any considerable effect on β-carotene concentration of fruits, except for mango and watermelon, where significantly (p < 0.05) higher levels were detected in the fresh samples. The results of DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging and reducing power assays revealed that fresh samples of starfruit and mango had relatively higher antioxidant activity. In case of linoleic acid peroxidation inhibition measurement, a significant (p < 0.05) but random variation was recorded between the fresh and freeze-dried fruits. Overall, in comparison to β-carotene and ascorbic acid, a good correlation was established between the result of TPC and antioxidant assays, indicating that phenolics might have been the dominant compounds contributing towards the antioxidant activity of the fruits tested.     

酚酸结构对酚酸-g-聚甘露糖醛酸抗氧化性能的影响

以海藻酸钠水解产物聚甘露糖醛酸(PM)为原料,通过聚甘露糖醛酸-乙二胺(PM-EDA)中间体与酚酸接枝共聚,制备了8种PM的酚酸(PA)接枝共聚物酚酸-g-聚甘露糖醛酸(PA-g-PM),并探究了PA结构对8种PA-g-PM抗氧化活性的影响。在n_PM:n_EDA=1:1.5,PM与两种活化剂碳二亚胺(EDC)、N-羟基琥珀酰亚胺(NHS)的摩尔比1:2:1,活化0 h,pH 8.0条件下,反应24 h,获得最高取代度(17.27%)的PM-EDA。PM的PA-g-PM接枝率在4.171±0.16 ~ 8.880±0.32 mg GA/g之间。UV-vis、FT-IR、XRD表征证实酚酸已成功接枝到PM上获得PA-g-PM。相比PM,8种PA-g-PM的对DPPH的清除率和对铁的还原力均显著提升。PA-g-PM的抗氧化性能与其中的酚羟基个数呈正相关关系,对位酚羟基PA-g-PM的抗氧化性能优于邻位酚羟基PA-g-PM的抗氧化性能,PA-g-PM中的酚羟基被甲氧基取代其抗氧化性能减弱。以期本研究结果为海藻酸钠在食品、化妆品、医药等行业高值开发利用奠定理论基础。     

窑法磷酸工艺研究现状及展望

本文介绍了CDK窑法磷酸和隧道窑窑法磷酸工艺原理及研发历程,指出了目前窑法磷酸工艺中存在的问题及影响生产的关键因素.针对工艺中存在的问题,提出了窑法磷酸工艺的研究方向和发展趋势.     

硼酸的生产应用现状及市场前景

介绍了当前硼酸的生产概况和应用现状,并结合实际提出了今后的发展前景。各国硼矿资源各有特点,其生产硼酸的方法也不尽相同,但以酸法为主。硼酸在玻璃工业、陶瓷、机械、电子、医药、农业、国防及现代科学技术领域有着广泛应用。未来世界硼工业将向集约化、规模化、精细化方向发展。高附加值的硼精细化工产品、新型含硼材料,专用(医药、试剂、照相、反应堆)级别的高纯或无水硼酸将有更为广阔的发展。     

测氧法研究受阻酚抗氧剂的抗氧化活性及反应动力学

采用测氧法考察了4种市售受阻酚抗氧剂的抗氧化活性,同时对其清除ROO·反应进行了动力学分析。结果表明:4种受阻酚抗氧剂对ROO·均具有良好的清除作用,并且抗氧化活性随着酚羟基浓度增加而增大。在同等的酚羟基浓度下,抗氧剂的抑制速率常数kinh值从大到小的顺序为抗氧剂1098、抗氧剂BHT、抗氧剂1010、抗氧剂1076。抗氧剂的抗氧化活性与功能基团的个数和对位取代基的供电性密切相关,酚胺复合型抗氧剂体现出更高的抗氧化活性。     

Enzymatic oxidative polymerization of pyrogallic acid for preparation of hindered phenol antioxidant

A novel antioxidant with high molecular weight was successfully synthesized via horseradish peroxide‐catalyzed oxidative polymerization of pyrogallic acid. As‐synthesized poly(pyrogallic acid), a black powder completely soluble in common organic solvents, has a number‐averaged molecular weight of about several thousand and consists of phenylene and oxyphenylene units. Besides, as‐prepared poly(pyrogallic acid) exhibits much better thermal stability and antioxidant capacity than butylated hydroxyanisole (denoted as BHA) and butylated hydroxytoluene (denoted as BHT), two kinds of commercial antioxidants. And it was also found that the higher phenolic content the pyrogallic acid polymer possess, the better antioxidant activity the poly(pyrogallic acid) shows. More importantly, poly(pyrogallic acid) could effectively inhibit the oxidation degradation of polypropylene (denoted as PP) during plastic processing. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41591.     

Chitosan conjugated with deoxycholic acid and gallic acid: A novel biopolymer-based additive antioxidant for polyethylene

Chitosan, as a novel bioadditive antioxidant for commodity polymer, is proposed. Chitosan is successfully conjugated with deoxycholic acid and gallic acid (chitosan-DC-GA) via a simple reaction using the 1-ethyl-3-(3′-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide conjugating agent at room temperature in a heterogeneous system. Chitosan-DC-GA shows a deoxycholic acid (DC) and gallic acid (GA) content of about 40% each. Chitosan-DC-GA exhibits DPPH radical scavenging ability with EC₅₀ 1 mg mL⁻¹ based on the EPR technique evaluation. A model case study of chitosan-DC-GA with low-density polyethylene (LDPE) confirms improvement in compatibility, as seen from the sheet clarity, as well as the good dispersion of chitosan-DC-GA in LDPE matrices, as observed by scanning electron microscope. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

新型季铵树脂的制备及杀菌性能

以γ-氯丙基三乙氧基硅烷、γ-胺丙基三乙氧基硅烷为原料,在碘化钾催化下,制备了有机硅氧烷叔胺单体[N(C3H6Si(OC2H5)3)3];单体经水解、缩合、季铵化,得到聚硅氧烷季铵盐型树脂.杀菌实验结果表明:当浓度为5.4×103个/mL的大肠杆菌或金黄色葡萄球菌菌悬液,分别以15 mL/min的流速通过1 g树脂层后,树脂对其杀菌率分别为100%和99.80%,再生后的树脂对两种细菌的杀菌率分别可以恢复到100%和99.76%.     

Conjugated linoleic acid and oxidative stress

At the present time, conjugated linoleic acid (CLA) is the subject of a growing number of studies since it has been demonstrated to possess anticarcinogenic and antiatherogenic activities in experimental animal models and to increase in some pathological states in humans. In both situations, CLA has been claimed to be involved in oxidative stress, as an antioxidant in the first case and as a primary product of a free-radical attack on polyunsaturated fatty acids (PUFA) in the other. The controversial results are due mostly to a lack of a suitable methodology because the presence of conjugated dienes (CD) in lipid moiety has been taken for years as evidence of lipid peroxidation due to the occurrence of this structure in fatty acid hydroperoxides. We have recently developed a new methodology that consists of the extraction of fatty acids, including CD fatty acid hydroperoxides, by mild saponification and their separation and identification by high-performance liquid chromatography with diode array detector. Fatty acid analyses of liver homogenate, oxidized in vitro either with Fe-ADP or t-butyl hydroperoxide (t-ButylHP), of lamb and rats fed CLA at levels known to prevent carcinogenesis, showed that CLA and its metabolites steadily decreased during oxidative stress and that they are more prone to oxidation than their corresponding methylene-interrupted fatty acids. No significant antioxidant effect of CLA was detected in any model tested. However, CD fatty acid hydroperoxides increased in the t-ButylHP model but not in the Fe-ADP model, owing probably to the degradation of CD fatty acid hydroperoxides induced by this oxidative agent. In conclusion, CLA and its metabolites seem to behave, under oxidative stress, as regular PUFA. Thus, it is highly unlikely that the peculiar effects of CLA are directly related to interference in lipoperoxidative processes.     

Lipoic/Capsaicin-Related Amides: Synthesis and Biological Characterization of New TRPV1 Agonists Endowed with Protective Properties against Oxidative Stress

α-Lipoic acid is a sulfur-containing nutrient endowed with pleiotropic actions and a safe biological profile selected to replace the unsaturated alkyl acid of capsaicin with the aim of obtaining lipoic amides potentially active as a TRPV1 ligand and with significant antioxidant properties. Thus, nine compounds were obtained in good yields following a simple synthetic procedure and tested for their functional TRPV1 activity and radical-scavenger activity. The safe biological profile together with the protective effect against hypoxia damage as well as the in vitro antioxidant properties were also evaluated. Although less potent than capsaicin, almost all lipoic amides were found to be TRPV1 agonists and, specifically, compound 4, the lipoic analogue of capsaicin, proved to be the best ligand in terms of efficacy and potency. EPR experiments and in vitro biological assays suggested the potential protective role against oxidative stress of the tested compounds and their safe biological profile. Compounds 4, 5 and 9 significantly ameliorated the mitochondrial membrane potential caused by hypoxia condition and decreased F2-isoprostanes, known markers of oxidative stress. Thus, the experimental results encourage further investigation of the therapeutic potential of these lipoic amides.     

Liquid-phase theoretical antioxidant activity trend of some cinnamic acid antioxidants

The trend in antioxidant activity of four cinnamic acid antioxidants, derived on the basis of their liquid-phase phenolic O H bond dissociation enthalpies, is determined theoretically, with the aid of the polarizable continuum model at the density functional theory level. Three solvents, differing in their hydrogen-bonding ability and polarity—n-heptane, acetonitrile, and ethanol—were used to model different environmental situations. The trends in solution-phase antioxidant activity appeared different in each solvent; still, the theoretical antioxidant activity trend derived in n-heptane was in excellent agreement with the experimental one in the lipid systems and the gas-phase system. Different ortho substituents show notably different solvent effects. These results could lead to the determination of reliable antioxidant activity trends in real-solution environments of interest in food or biological science frameworks.     

毛细管法测定防老剂D与BHT的熔点

为了准确测定防老剂D与BHT的熔点,用两端开口毛细管法、一端开口毛细管法和数字熔点仪测定了两种防老剂的熔点。结果表明,两端开口毛细管法测得的数据精密度较高,而且此法方便、经济。总结了两端开口毛细管法测定防老剂D与BHT的影响因素及注意事项。     

硫酸法钛白废酸利用及发展简况

简要介绍了目前中国钛白粉的生产状况以及发展前景，着重介绍了硫酸法钛白粉生产中排出的废酸的几种利用方法，并作了详细的阐述：如废酸用于钢材酸洗除锈，生产聚硫酸铝铁混凝剂，生产工业级七水硫酸镁，浓缩回收，联产红、白石膏，还原解毒铬渣。强调今后钛白发展必须树立环保治理新理念，变末端治理为全过程清洁生产，重点应放在改变矿源结构，改革生产工艺，从源头上降低“三废”的排放，并进一步提高废酸利用的资源化程度。     

枞酸氧化反应及其抗氧剂的研究

采用紫外分光光度分析方法研究了枞酸在聚乙烯膜上的氧化反应,考察了MBP,FMH,DBH,DSB3,DSB65种抗氧剂对枞酸氧化反应的影响,提出了用抗氧化值AO考核抗氧剂的抗氧化能力。实验结果表明,枞酸氧化反应动力学在初期阶段呈表观一级,后期受氧化膜影响不呈表观一级。当反应温度为35,40,45,50,55℃时,5种抗氧剂都表现出不同程度的抗氧化能力,其中MBP,DBH,DSB6抗氧剂的抗氧化能力显著,在35℃下其抗氧化值AO分别是109.92,50.93,209.84。