Key Role of Some Specific Occupied Molecular Orbitals of Short Chain n-Alkanes in Their Surface Tension and Reaction Rate Constants with Hydroxyl Radicals: DFT Study

Basing on the DFT calculations we propose the new theoretical model which describes both the surface tension σ of the short chain n-alkanes at their normal boiling points and their reaction rate constants with hydroxyl radicals OH• (at 297 ± 2 K) on the basis of their molecular orbital electronic characteristics. It has been shown that intermolecular dispersion attraction within the surface liquid monolayer of these compounds, as well as their reaction rate constants k with OH• radicals are determined by the energies Eorb of the specific occupied molecular orbitals which are the same in the determination of both the above physico-chemical characteristics of the studied n-alkanes. The received regression equations confirm the theoretically found dependences between the quantities of σ and k and the module |Eorb|. For the compounds under study this fact indicates the key role of their electronic structure particularities in determination of both the physical (surface tension) and the chemical (reaction rate constants) properties.

Sonme Factors that Affect the Free Radical-scavenging Activity of Tea Extracts

Some factors that affect the free radical-scavenging activety of two tea extracts were studied in vitro. It was found that concentration of tea extract or heating tea extract or treating with activated carbon and diatomite all had obvious effect on the scavenging activety of green tea extract ,but heating or treating with diaomite had less effect on the scavenging activity of black tea extract. Ascorbic acid, for having synergic effect with tea extracts, could enhance the scavenging activity of tea extracts markedly, and the contrary was cupric ion. Reducing sugars such as fructose and glucose also had some syncrgic effect to tea extracts.

New Active Organic Substance in Oyster Shell Capable of Scavenging Oxygen Free Radicals with High Efficiency

A light purple organic active substance capable of scavenging hydroxyl radical（OH） with a high efficiency was extracted from Oyster shell at an extraction rate of 2.49%. It was found for the first time that this active substance may scavenge OH with the efficiency far higher than that of vitamin C. This active substance may scavenge also superoxide radical（O2） although the scavenging efficiency is far lower than that of vitamin C. Infrared spectrometry and routine chemical analysis primarily reveal that this active substance belongs to glycoprotein.

Extraction of Astragalus Polysaccharides and Ganoderma lucidum Mycelia Polysaccharides and Their in Vitro Antioxidative Effects

[Objectives]To explore the extraction and in vitro antioxidant effects of astragalus polysaccharides(APS)and Ganoderma lucidum mycelia polysaccharides(GLMPS).[Methods]By studying the polysaccharides of the herbal medicinal material Astragalus membranaceus and the fungal medicinal material Ganoderma lucidum mycelia,two polysaccharides were mixed according to different proportions and concentrations by using the principle of traditional Chinese medicine compound combination.The effect of polysaccharides on the scavenging ability of hydroxyl radical system was determined by salicylic acid method.[Results]When the compound ratios of GLMPS and APS were 1∶1,1∶4,1∶5,4∶1,and 5∶1,the scavenging effect of compound polysaccharides was better than that of single-component polysaccharides,and with the increase of concentration,the scavenging effect increased.When the ratio of GLMPS and APS was 5∶1,the hydroxyl radical scavenging rate of the compound polysaccharide reached 59.77%,which was 18.72%higher than that of single GLMPS and 28.58%higher than that of single APS.The scavenging effect of compound polysaccharide is closely related to the compound ratio and concentration.[Conclusions]APS and GLMPS can obtain better hydroxyl radical scavenging ability than single-component polysaccharides through compounding in appropriate proportions.In addition,within a suitable concentration range,as the concentration increases,the scavenging ability also increases.

Study on Solid Fermentation and Antioxidant Function of Natto

[Objectives]To study the optimum conditions of solid fermentation of natto with antioxidant function as an index.[Methods]Single factor experiment and orthogonal experiment were designed to study the effects of temperature,time,initial pH and inoculum amount on the antioxidant activity of natto solid fermentation.The optimum conditions of natto solid fermentation were determined and the antioxidant ac-tivity of natto extract was compared.[Results]The optimal fermentation conditions were as follows:temperature 32℃,initial pH 7.0,inocu-lation amount 8%,fermentation time 32 h.The hydroxyl radical scavenging rate of natto solid fermentation crude extract was the highest,which was 82.7%.The optimized nato fermentation extract showed stronger scavenging ability for-OH and O,:,and showed obvious dose-effect relationship.ICso was 3.63 and 4.24 mg/mL,respectively,and the scavenging efficiency was 1.3 and 1.9 times higher than that of the unoptimized fermentation extract,respectively.[Conclusions]Natto is rich in nattokinase and other functional factors,and its antioxidant ac-tivity can be improved by optimizing fermentation technology,so that natto products can be widely used,including cosmetic raw materials,nat-to skin care soap,health food and medicine,etc.,and have a broader development prospect.

Designed synthesis of chlorine and nitrogen co-doped Ti_(3)C_(2)MXene quantum dots and their outstanding hydroxyl radical scavenging properties

As a novel zero-dimensional(0D)material,metal carbides and/or carbonitrides(MXenes)quantum dots(MQDs)show unique photoluminescence properties and excellent biocompatibility.However,due to the limited synthesis methods and research to date,many new features have yet to be uncovered.Here,to explore their new properties and expand biological applications,chlorine and nitrogen co-doped Ti_(3)C_(2)MXene quantum dots(Cl,N-Ti_(3)C_(2)MQDs)were designed and synthesized,and their hydroxyl radical scavenging properties were investigated for the first time,revealing outstanding performance.Cl,N-Ti_(3)C_(2)MQDs was directly stripped from bulk Ti_(3)Al C_(2)by electrochemical etching,while N and Cl are successfully introduced to carbon skeleton and Ti boundaries in the etching process by electrochemical reactions between selected electrolytes and Ti_(3)C_(2)skeleton,respectively.The obtained Cl,N-Ti_(3)C_(2)MQDs exhibit large surface-to-volume ratio due to small particle size(ca.3.45 nm)and excellent higher scavenging activity(93.3%)and lower usage(12.5μg/m L)towards hydroxyl radicals than the previous reported graphene-based nanoparticles.The underlying mechanism of scavenging activity was also studied based on the reduction experiment with potassium permanganate(KMnO_(4)).The reducing ability of the intrinsic Ti_(3)C_(2)structure and electron donation of double dopants are the main contributors to the outstanding scavenging activity.

Consensus Hologram QSAR Model Studying on the Aqueous Hydroxyl Radical Oxidation Reaction Rate Constants of Organic Micropollutants

The combination of hologram quantitative structure-activity relationship(HQSAR)and consensus modeling was employed to study the quantitative structure-property relationship(QSPR)model for calculating the aqueous hydroxyl radical oxidation reaction rate constants(kOH)of organic micropollutants(OMPs).Firstly,individual HQSAR model were established by using standard HQSAR method.The optimal individual HQSAR model was obtained while setting the parameter of fragment distinction and fragment size to“B”and“3~6”respectively.Secondly,consensus HQSAR model was established by building the regression model between the kOH and the hologram descriptors with consensus partial least-squares(cPLS)approach.The obtained individual and consensus HQSAR model were validated with a randomly selected external test set.The result of external test set validation demonstrates that both individual and consensus HQSAR model are available for predicting the kOH of OMPs.Compared with the optimal individual HQSAR model,the established consensus HQSAR model shows higher prediction accuracy and robustness.It is shown that the combination of HQSAR and consensus modeling is a practicable and promising method for studying and predicting the kOH of OMPs.

大球盖菇多肽的制备、抗氧化及抗肿瘤活性的研究

[目的]大球盖菇作为近年来在我国迅速崛起的食用菌,以其卓越的营养价值和多样的保健功效受到市场的青睐。然而,尽管其产量迅猛增长,深度加工技术的滞后和创新产品开发的不足已成为制约大球盖菇产业发展的关键因素。因此,本研究旨在优化大球盖菇多肽的制备工艺,并评价其体外抗氧化和抗肿瘤活性,为大球盖菇的深度加工和产品创新提供科学依据。[方法]以蛋白水解度为评价指标,在蛋白酶筛选的基础上,通过单因素和正交试验获得大球盖菇多肽的最佳制备工艺,并通过超滤分级纯化获得3个多肽组分(M1:>10 kDa、M2:3~10 kDa、M3:<3 kDa);通过DPPH·和ABTS^(+)·清除率的测定评价多肽体外抗氧化活性。通过常见肿瘤细胞增殖抑制率的测定评价多肽抗肿瘤活性。[结果]胰蛋白酶酶解制备大球盖菇多肽的最佳工艺为料液比1∶20 g/mL、酶添加量4000 U/g、酶解时间3 h,在该条件下大球盖菇蛋白的水解度为28.31%,比优化前提高了3倍。所制备的大球盖菇多肽对DPPH·和ABTS^(+)·的清除率最高可达69.2%和91.4%,高于以往相关报道。3个多肽组分对4种常见的肿瘤细胞(宫颈癌细胞HeLa、肺癌细胞NCI-H460、乳腺癌细胞BT549、肝癌细胞HepG2)的抑制效果不同,但均呈现浓度依赖性。M1和M3对肺癌细胞NCI-H460的抑制效果最好,而M2主要抑制宫颈癌细胞HeLa;其中,500μg/mL M3对肺癌细胞NCI-H460的抑制率达30.28%。[结论]胰蛋白酶酶解制备大球盖菇多肽的工艺优化后,所制备的多肽具有良好的抗氧化活性和抗肿瘤活性。

电子束辐照降解诺丽多糖溶液的工艺及抗氧化活性研究

本研究以诺丽果发酵汁为原料,采用热水浸提法提取获得诺丽多糖溶液,以降解率为指标,选取诺丽多糖浓度、电子束辐照强度、辐照温度为影响因素,通过单因素和正交试验筛选得到电子束辐照诺丽多糖溶液降解率的最佳工艺。结果表明,最佳工艺参数为诺丽多糖浓度为90 mg/L,辐照强度为30 kGy,辐照温度为75℃,诺丽多糖溶液的降解率为71.23%;诺丽多糖浓度为90 mg/L时,DPPH、·OH和O_(2-)·自由基清除率分别为59.7%、66.8%、68.2%,说明电子束优化工艺处理后诺丽多糖溶液有较强的清除DPPH、·OH和O_(2-)·自由基能力。

Kinetics of Ozonation of Typical Sulfonamides in Water

Objective To investigate the kinetic rate constants ozone and hydroxyl radicals towards two groups of antimicrobials --sulfadiazine （SD） and sulfamethoxazole （SMX）.Methods The solute consumption method was used to detect the rate constants of ozone alone with sulfadiazine and sulfamethoxazole, and tertiary butanol was selected as a scavenging agent and pH was adjusted to 2.5 by adding orthophosphate buffers （OB）; and the competition kinetics studying methodwith nitrobenzene as a reference was applied to measure the rate constants of hydroxyl radicals towards sulfadiazine and sulfamethoxazole, and oH was adjusted to 7.0 bv adding OB.Results The rate constants of SD and SMX with ozone alone were 261 mol^-1· dm^3 · s^-1 and 303 mol^-1· dm3 · s-1 by calculating in low reaction system. The rate constants of hydroxyl radicals with SD and SMX were 2.2×1010 mol^-1 · dm^3 · s^-1 and 2.7×1010 mol^-1· dm^3 · s^-1, respectively. Moreover, the rate constants of hydroxyl radicals with SMX were found to have increased from 3.6×109 mol^-1· dm^3 · s^-1 to 2.8×1010 mol^-1· dm^3 · s^-1 with pH value rising from 5.0 to 7.8. Conclusion SMX and SD are both refractory to ozone oxidation alone, and are liable to be degraded by hydroxyl radicals, and the rate constants of SMX with the hydroxyl radical slightly increases with pH rise.

Pulse radiolysis study on the free radical scavenging activities of puerarin

The free radical scavenging activities of puerarin towards nitrogen dioxide radicals (NO 2 ˙ ), nitric oxide radicals (NO˙) and hydroxyl radicals (OH˙) were investigated by pulse radiolysis. Puerarin reacted with (NO 2 ˙ ) or (NO˙) to form puerarin-4-O˙ with the absorption maximum at 340 nm, but reacted with OH˙ to form at least three transient species including puerarin-2-O˙, puerarin-4-O˙ and [puerarin-OH]˙with a broad absorption spectrum band (300-750 nm). In addition, the reaction rate constants of puerarin reacting with NO 2 ˙ , and NO˙ were determined as 2.6 × 108, 1.7× 108 and 3.9 × 109 L · mol?1 · s?1, respectively.

Radiation-induced reduction of chromium(VI) in aqueous solution by γ-irradiation in a laboratory-scale

Radiation-induced reduction of chromium（Ⅵ）（Cr（Ⅵ） by ,γ-irradiation was studied with an initial concentration of 42 mg/L in aqueous solutions. Several factors which might affect the reduction of Cr（Ⅵ） to Cr（Ⅲ） were examined, pH of aqueous solution affects the reduction efficiency significantly. Acidic condition of aqueous solution accelerates the process. At pH 2, a reduction of 86.2% was achieved with the absorbed dose of 15 kGy, while, with the same dose, at pH 5 and 7, the reduction ofCr （Ⅵ） were only 36.3% and 22.2%, respectively. Ethanol （0.1% in V：V） and sodium carbonate （1 mmol/L） were added into the solution respectively as relatively non-toxic hydroxyl radical scavengers. Reduction rate increased greatly in the presence of ethanol at each pH. Reduction efficiency of Cr（Ⅵ） was enhanced in neutral condition with the addition of sodium carbonate, however, no enhancement was found in acidic condition. The reduction of Cr（Ⅵ） was restrained when the solution was saturated with oxygen; however, the restraint was not significant.

Antioxidant activities of different extracts from Amomum longiligulare Fruits

Objective:To study the antioxidant activities of five extracts ofAmomi longiligulare (A. longiligulare) to determine the antioxidant fraction.Methods: The ethanol extract ofA. longiligulare was extracted by systematic solvent extraction to obtain the petroleum ether, dichloromethane, ethyl acetate, n-butanol fractions successively. Thein vitro antioxidant activities of the five extracts were evaluated by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical and hydroxyl radical (OH-) scavenging assay methods.Results: The five extracts showed different extent of antioxidant activities in vitro, especially the ethyl acetate and dichloromethane fractions.Conclusion: The difference of antioxidant activity of different extracts may be associated with the type and structure of antioxidant components in each fraction of A. longiligulare fruits.

出芽短梗霉LHS-m022黑色素葡聚糖的发酵影响因素和生物活性

为探索出芽短梗霉LHS-m022黑色素多糖的发酵影响因素和生物活性,采用菌种发酵、分离提取及生物检测方法,对发酵液性质、产物收率、生物转化率及生物活性进行测定分析。结果表明,LHS-m022黑色素多糖发酵的最佳碳、氮源分别是蔗糖和胰酪蛋白胨,蔗糖最佳浓度为60 g/L;发酵培养基中诱导剂L-多巴的最适添加量为2.0 g/L,发酵液黑变活性和生物转化率分别是2.481和71.93%;细胞通透剂鼠李糖脂的最适添加量是0.021μL/L,发酵液黑变活性和生物转化率分别高达2.794和73.9%。全波长扫描、FTIR与HPLC分析表明,WAI为黑色素,PsB为黑色素葡聚糖结构。研究结果揭示,粗黑色素葡聚糖样品经121℃以上高温处理,仍然得到95.37%的絮凝率。采用1.50和2.00 g/L的样品浓度进行检测,分别得到99.55%的羟自由基清除活性和99.00%的抗氧化活性。

不同泉水对蓝靛果浆DPPH清除率的影响研究

以DPPH自由基清除率为指标,考察蓝靛果汁与4种瓶装泉水混合后样品液体外抗氧化活性受水质的影响及变化规律。结果表明,蓝靛果汁与泉水按比例混合后,其DPPH自由基清除率随果汁浓度变化出现一个最大值,最大DPPH自由基清除率为81.44%。受水中离子含量的影响,浓度在30%后会呈现下降趋势,其中具有显著相关的离子为Na离子和Ba离子。

基于均匀试验设计的3种浆果花色苷体外协同抗氧化研究

本研究旨在探究3种浆果花色苷的协同抗氧化活性,以DPPH自由基清除率为评价指标,采用均匀试验设计法优化3种浆果花色苷协同抗氧化组合。经过统计分析和数学回归模型拟合得到最优组合:笃斯越橘花色苷(DP)、黑加仑花色苷(HP)、蓝靛果花色苷(LP)最佳浓度分别为0.08 mg/mL、0.14 mg/mL和0.18 mg/mL,对DPPH自由基的实际清除率为(97.67±0.51)%,接近理论期望值100%,说明模型优选的组合具有可行性。通过协同效应分析,优选组合清除DPPH自由基和羟自由基的协同效应指数CI值分别为0.297和0.651,进一步说明DP、HP、LP3种浆果花色苷具有显著协同抗氧化效果。研究成果可为天然抗氧剂及小浆果功能产品研发提供依据。

红曲糟源酶解蛋白肽的功能性评价

【目的】研究不同蛋白酶对红曲糟酶解的效果,并对其酶解液进行功能性评价,为红曲糟源蛋白肽的研发制备提供理论支持。【方法】以提高蛋白含量后的红曲糟为原料,利用碱性蛋白酶、胰蛋白酶、动物蛋白酶、木瓜蛋白酶、菠萝蛋白酶、胃蛋白酶、复配酶制剂F106、酵母抽提酶等不同蛋白酶进行酶解,考察其酶解率、1,1-二苯基-2-三硝基苯肼(DPPH)和2,2-联氮-二(3-乙基-苯并噻唑-6-磺酸)二铵盐(ABTS)自由基清除抗氧化能力、黄嘌呤氧化酶(Xanthine oxidase,XOD)和血管紧张素转化酶(Angiotensin converting enzyme,ACE)抑制活性等生物活性功能。【结果】蛋白酶解率最高的为动物蛋白酶和胰蛋白酶酶解处理,分别为(71.43±1.03)%和(70.20±0.32)%。DPPH自由基清除抗氧化能力最优的是胃蛋白酶、碱性蛋白酶和酵母抽提酶酶解处理,蛋白肽的半数效应浓度(Median effective concentration,EC50)分别为(2.78±0.34)mg·mL^(-1)、(3.02±0.03)mg·mL^(-1)、(3.24±0.65)mg·mL^(-1);ABTS自由基清除抗氧化能力、XOD抑制活性能力最优的均为胃蛋白酶和碱性蛋白酶酶解液,其蛋白肽的EC50值分别为(1.54±0.07)mg·mL^(-1)、(6.45±0.27)mg·mL^(-1)和(10.71±0.06)mg·mL^(-1)、(17.68±0.04)mg·mL^(-1),二者的XOD半数抑制指数分别为(1.28±0.01)、(1.78±0.03);ACE抑制活性最优的为碱性蛋白酶酶解液和木瓜蛋白酶酶解液,蛋白肽的EC50值均为(0.27±0.01)mg·mL^(-1),半数抑制指数分别为(118.40±3.53)、(98.35±1.95)。【结论】红曲糟源蛋白经不同蛋白酶酶解后的肽段具有不同的生物活性,其中以胃蛋白酶酶解的XOD抑制活性能力较强,碱性蛋白酶和木瓜蛋白酶酶解的ACE抑制活性较优。

荧光探针法测定磷酸酯与羟基自由基的反应速率常数

基于香豆素与羟基自由基(·OH)反应后产生的7-羟基香豆素具有强荧光性的特点,使用香豆素作为荧光探针,对不同浓度磷酸三丁酯(TBP)和磷酸三异戊酯(TiAP)水溶液经γ射线辐照后的·OH产额进行了研究,并通过准一级动力学拟合分别测定了TBP及TiAP与·OH室温下的反应速率常数,测得k_(TBP)=(9.0±0.2)×10^(9)L/(mol·s),k_(TiAP)=(5.3±0.2)×10^(9)L/(mol·s)。由于TiAP的疏水性比TBP强,其与·OH的反应速率常数小于TBP,导致加入相同浓度的磷酸酯后,产生的·OH产额高于TBP体系。该工作为研究萃取剂与·OH反应提供了简单、方便、有效的方法。

4种不同来源花青素的稳定性及抗氧化性比较

为更好地探索不同原料的花青素作为食品着色剂和营养剂的潜力,对蓝莓、紫薯、紫甘蓝、黑豆的花青素进行提取,对4种原料花青素含量进行比较,并探究4种原料花青素的抗氧化性以及在不同因素下(光照、pH值、温度、金属离子、氧化剂、还原剂、葡萄糖浓度、蛋白质)的稳定性。结果表明,花青素含量排序为紫甘蓝(435.84 mg/L)>紫薯(401.77 mg/L)>蓝莓(388.08 mg/L)>黑豆(177.34 mg/L)。稳定性最佳的原料花青素为紫甘蓝花青素,抗氧化性最强的为蓝莓花青素(羟自由基清除率、DPPH自由基清除率、ABTS^(+)自由基清除率分别为76.41%、83.05%、88.13%,总还原能力测得吸光值为2.04)。