带鱼黄嘌呤氧化酶抑制肽制备及工艺优化

目的 制备带鱼黄嘌呤氧化酶抑制肽,研究含肌肽类活性肽的带鱼提取物对黄嘌呤氧化酶的抑制作用。方法 以带鱼为原料,通过超声辅助酶法制备带鱼黄嘌呤氧化酶抑制肽,高效液相色谱法测定肌肽类活性肽的含量。结果 以肽粉得率和黄嘌呤氧化酶抑制率为指标,筛选得到碱性蛋白酶为最佳反应用酶。以单因素实验为基础,通过Box-Behnken响应面分析法,以水解度、黄嘌呤氧化酶抑制活性、肌肽及鹅肌肽含量为响应值,优化得到酶解最优条件:酶解时间5 h,超声时间21 min,酶解温度49℃。在此条件下,得出水解度21.90%、黄嘌呤氧化酶抑制率52.03%、鹅肌肽含量0.66%和肌肽含量为0.15%,与回归理论模型基本符合。在最优酶解方案的基础上,将酶解液进一步分成不同组分,可得到肌肽类活性肽含量升高,抑制活性变大。结论 肌肽类活性肽对黄嘌呤氧化酶活性的抑制有着积极的作用,这为工业化利用带鱼制备黄嘌呤氧化酶抑制肽提供理论及指导。     

青占鱼黄嘌呤氧化酶抑制肽制备工艺优化

目的 本研究以青占鱼为原料,对黄嘌呤氧化酶(xanthine oxidase,XOD)抑制肽的制备条件进行优化。方法 选用五种蛋白酶对其水解制备黄嘌呤氧化酶抑制肽,测定XOD抑制率和水解度并用以评价效果,通过单因素和响应面分析相结合的实验方法优化酶解条件,最后对其分子量分布情况进行了检测分析。结果 结果表明复配酶制剂为最适酶,最佳酶解工艺为：加酶量4000U/g,酶解时间4h,酶解温度55℃,pH 7.0,料液比1:2;同时测得最优工艺下XOD抑制率和水解度的实际值分别为65.21%和18.5%,与理论值基本无差别。采用该法制备的青占鱼XOD抑制肽分子量分布情况为：5500~3000Da的肽段占比56.44%,3000~1500Da的肽段占比31.07%,＜1500Da的肽段占比12.49%。结论 本研究可为青占鱼制备XOD抑制肽的生产工艺与机理研究提供一定的技术参考与理论支持。     

蓝圆鲹黄嘌呤氧化酶抑制肽的制备及其活性分析

以蓝圆鲹为原料,选用胰蛋白酶、木瓜蛋白酶、中性蛋白酶、复合蛋白酶及碱性蛋白酶对其进行水解.以酶解产物黄嘌呤氧化酶(xanthine oxidase,XOD)的抑制活性为指标,通过单因素试验及正交试验确定了最佳的酶解制备条件.结果显示,最佳酶解条件为采用中性蛋白酶,加酶量0.3％(质量分数),料液比1:2(g:mL),p...     

仿刺参酶解液抑制黄嘌呤氧化酶活性的研究

目的:为了充分利用仿刺参这一海洋资源,开发其活性成分,研究了仿刺参的最优酶解条件并探讨仿刺参通过抑制黄嘌呤氧化酶活性对大鼠高尿酸血症的预防效果。方法:以水解度为指标,通过单因素试验对酶解温度、酶解时间、加酶量等酶解工艺参数进行研究,采用响应面法优化酶解工艺。以酵母膏淀粉混合液配合氧嗪酸钾构建大鼠高尿酸血症模型。分别灌胃造模后的SD大鼠,30 d后,测定大鼠的脏器系数及血清中XOD活力,UA和BUN含量。利用基因芯片技术比较不同组别间基因的表达水平。同时利用RT-qPCR技术验证基因芯片结果。结果:选用复合蛋白酶,酶解温度55℃,酶解时间136 min,加酶量1.97%,水解度最高。仿刺参酶解液能显著改善大鼠的脏器系数,降低大鼠血清中的UA和BUN含量,降低XOD活性,抑制黄嘌呤氧化酶的活性,降低尿酸的合成产生。与模型组的差异表达比较,试验组基因表达水平有显著改变,其中表达上调的基因36个,表达下调的143个。结论:仿刺参营养丰富,可以抑制黄嘌呤氧化酶的活性,具有抗高尿酸血症的作用,是一种预防痛风的食品。     

超声辅助酶解制备大米蛋白黄嘌呤氧化酶活性抑制肽的工艺条件优化

摘 要: 本文以大米蛋白为原料,研究了碱性蛋白酶酶解法制备黄嘌呤氧化酶（Xanthine Oxidase,XOD）活性抑制肽,并对其体外功能活性进行评价。研究了蛋白酶种类、底物浓度、酶解温度、加酶量、酶解pH、酶解时间对大米蛋白水解度（degree of hydrolysis,DH）及酶解产物对黄嘌呤氧化酶活性抑制率的影响,探讨了不同超声处理方式对酶解过程的影响,通过响应面法对实验条件进行了优化结果如下：采用碱性蛋白酶,底物浓度5 %,酶解温度为56 ℃,加酶量为8000 U/g,酶解pH为10,超声功率70 W,超声酶解60 min,对所制备的大米蛋白黄嘌呤氧化酶活性抑制肽的功能活性进行了评价。在最优条件下其黄嘌呤氧化酶抑制活性的IC50为1.55 mg/mL, ABTS自由基清除作用、羟基自由基清除作用、DPPH自由基清除作用的IC50值分别为0.49、12.48、3.88 mg/mL。     

苦丁茶总黄酮纯化工艺及其黄嘌呤氧化酶抑制活性研究

以D101大孔树脂对苦丁茶粗提物中的总黄酮进行分离纯化,确定最佳纯化工艺条件,测定纯化前后的样品总黄酮的纯度,并检测纯化前后样品对黄嘌呤氧化酶（xanthine oxidase,XOD）的体外抑制活性。通过单因素试验得到最佳优化工艺条件为上样液pH值为3、洗脱液乙醇浓度70%、上样液浓度3.0 mg/mL、上样液流速2.0 mL/min、洗脱液流速2.0 mL/min、上样量55 mL、洗脱液体积40 mL。纯化后样品纯度由75.53%提高至94.40%,对XOD的IC50分别为（228.22±1.07）μg/mL 和（135.74±1.02）μg/mL。     

超声辅助提取苦丁茶多糖的工艺优化及其对黄嘌呤氧化酶抑制活性

目的：优化苦丁茶多糖的提取工艺,分析其对黄嘌呤氧化酶的抑制活性。方法：以得率为指标,采用响应面优化超声辅助法研究料液比、超声时间、超声温度、超声功率对苦丁茶多糖的得率的影响;通过体外实验测定苦丁茶多糖对黄嘌呤氧化酶的抑制率及其动力学常数K_i。结果：响应面试验优化条件为：料液比1:25 g/mL,超声时间60 min,超声温度40℃,超声功率260 W,得到得率为5.85%。苦丁茶多糖对黄嘌呤氧化酶的抑制率随物质量浓度增大而增加,IC₅₀为1.28 mg/mL,其对黄嘌呤氧化酶抑制作用类型属于竞争性可逆抑制,抑制动力学常数K_i为0.62 mg/mL,结论：苦丁茶多糖能够抑制黄嘌呤氧化酶的活性,其可作为潜在的预防高尿酸血症的食品或保健品进行深入研究,以期对苦丁茶的综合利用提供理论数据。     

芹菜素对黄嘌呤氧化酶活性的抑制机理研究

利用紫外、荧光光谱法和圆二色谱法结合分子对接技术探讨芹菜素对黄嘌呤氧化酶(xanthine oxidase,XO)催化活性(底物黄嘌呤)抑制作用机理。结果表明:芹菜素具有明显可逆的混合竞争型抑制XO作用,其半数抑制浓度(IC50)和抑制常数(Ki)分别为8.63、2.35μmol/L;芹菜素主要通过疏水作用力与XO形成基态复合物,并引起XO二级结构(α-螺旋含量增加)发生改变;分子对接结果显示芹菜素通过结合到XO的活性空腔,并与周围氨基酸相互作用,占据疏水通道,从而抑制XO活性。     

酶解马鲛鱼下脚料制备海鲜酱工艺优化

对马鲛鱼下脚料水提液进行酶解,通过单因素及正交酶解试验,优化了马鲛鱼下脚料的酶解工艺,再利用酶解液制备海鲜调味酱,并与市售海鲜酱的感官品质进行对比分析。结果表明,马鲛鱼下脚料的最佳酶解工艺条件为：中性蛋白酶用量500 U/g,液料比（V_水∶m_下脚料）3∶1 （mL/g）,酶解温度55 ℃,pH值 7.5,酶解时间5 h,该酶解条件下酶解液中氨基酸态氮的质量浓度高达（0.325±0.004） g/100 mL。制备的海鲜酱与市售海鲜酱的口感相当,产品理化及微生物指标符合相关国家标准要求。     

诃子超微粉的工艺优化及其对黄嘌呤氧化酶活性的影响

目的制备诃子超微粉进行粉体学性质检测,对其制备工艺进行优化。方法:以黄嘌呤氧化酶(Xanthine oxidase,XOD)抑制率为评价指标,以球料比、冷冻时间、转速、球磨时间为影响因素进行单因素试验;在此基础上,正交实验试验优化诃子超微粉碎工艺。建立优化后的诃子超微粉的高效液相色谱(High Performance Liquid Chromatography,HPLC)指纹图谱,并与诃子超微粉进行对比。结果: 采用球磨法制备了诃子超微粉,诃子超微粉可显著改善普通粉的粉体学性质,降低药粉粒径;诃子超微粉最优制备条件为：球料比5:1、冷冻时间40 min、转速400 r/min、球磨时间1 h,优化后的超微粉粒径为22.4μm,5 mg/mL黄嘌呤氧化酶抑制率为69.10%。经HPLC分析,优化前后的二种诃子超微粉末指纹图谱主要成分基本一致,超微粉碎工艺未破坏诃子成分。结论:优化后的诃子超微粉抗黄嘌呤氧化酶活性更佳,为诃子超微粉在高尿酸血症中的应用提供了基础。     

Inhibition of xanthine oxidase activity by an oxathiolanone derivative of quercetin

An oxathiolanone derivative of rutin could be produced in the stomach after the ingestion of rutin containing foods, and the oxathiolanone derivative could be hydrolysed to an oxathiolanone derivative of quercetin (quercetin-oxathiolanone) in the intestine. Quercetin-oxathiolanone as well as quercetin inhibited xanthine oxidase. Approximately 0.05 μM quercetin-oxathiolanone inhibited the activity by 50%, whereas 50% inhibition by quercetin was observed at approximately 0.4 μM. The results suggested that quercetin-oxathiolanone can be used as an effective inhibitor of xanthine oxidase and that the ingestion of rutin-rich foods may be useful to prevent the increase in the blood concentration of uric acid.     

Xanthine oxidase inhibitory activity of alkyl gallates

A series (C1-C12) of alkyl gallates was examined for their effects on the activity of xanthine oxidase. Octyl (C8), decyl (C10), and dodecyl (C12) gallates competitively inhibited uric acid formation generated by xanthine oxidase, and the inhibition increased upon increasing the alkyl chain length. Interestingly, neither menthyl nor bornyl gallates inhibited uric acid formation. These data indicate that the hydrophobic alkyl portion is associated with the xanthine-binding site in the Mo-binding domain. It is likely that the linear alkyl portion interacts with the hydrophobic domain close to the binding site, and the hydrophobic interaction is crucial to inhibit the xanthine oxidase reaction. On the other hand, all of gallic acid and its esters equally suppress superoxide anion generation catalyzed by xanthine oxidase at low concentration. The suppression is not due to scavenging activity of these gallates but due to reduction of xanthine oxidase by these gallates. The reduced enzyme catalyzes the reaction to generate hydrogen peroxide and uric acid.     

Electrochemical biosensor based on gold coated iron nanoparticles/chitosan composite bound xanthine oxidase for detection of xanthine in fish meat

A xanthine oxidase was immobilized covalently onto chitosan bound gold coated iron nanoparticles (CHIT/Fe-NPs@Au) electrodeposited on the surface of pencil graphite electrode (PGE). A xanthine biosensor was fabricated using XOD/CHIT/Fe-NPs@Au/PGE as working, Ag/AgCl as reference and Pt as auxiliary electrode connected through potentiostat. The enzyme electrode was characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and electrochemical impedance spectroscopy (EIS). The biosensor exhibited optimum current response within 3 s at pH 7.4, 35 °C and working range 0.1–300 μM, when polarized at 0.5 V vs Ag/AgCl. The sensitivity of the biosensor was 0.001169 mAμ M^–1 cm^–2 with detection limit of 0.1 μM (S/N = 3). The biosensor showed only 25% loss in its initial activity after its 100 uses over 100 days, when stored at 4 °C.     

梅花总黄酮对黄嘌呤氧化酶的抑制作用及其抗氧化活性评价

评价了梅花总黄酮对黄嘌呤氧化酶（XOD）的抑制作用及其抗氧化活性。通过体外评价实验测定梅花总黄酮对XOD的抑制作用,并分别采用DPPH自由基法、铁离子还原法（FRAP）和血液总抗氧化能力测定法评价其抗氧化活性。结果显示,梅花总黄酮对XOD的抑制呈现浓度依赖关系,半抑制浓度（IC50值）为85.45μg/mL;梅花总黄酮清除DPPH自由基的能力强于竹叶黄酮,但弱于维生素C和芦丁;梅花总黄酮还原铁离子的FRAP值为3.38mmol/mg,是芦丁的1.44倍和竹叶黄酮的1.29倍;血液总抗氧化能力的测定结果从强到弱依次为：维生素C〉梅花总黄酮〉竹叶黄酮〉芦丁。研究表明,源自青梅花的生物总黄酮具有优良的生物抗氧化能力和显著的XOD抑制活性,可作为潜在的抗氧化应激和预防高尿酸血症的膳食功能因子进行深入研究和开发。     

Antioxidative and xanthine oxidase inhibitory activities and phytochemical screening of the hydro-alcoholic extract of mace,aril of Myristica fragrans: Implication as an adjuvant therapy in gout

Myristica fragrans derivatives are used as spices in cuisines and also serve as an important source of traditional medicine worldwide. The present study has evaluated the antioxidative potential of the hydro-methanolic extract of the fruit aril of M. fragrans, which is also referred to as mace. This study also includes a quantitative phytochemical assessment of the extract and focuses on the ability of the extract to inhibit xanthine oxidase, a molecular target involved in nucleic acid metabolism and the enzyme responsible for the development of gout disease. The extract was found to contain different classes of secondary metabolites, including flavonoids, phenolics, tannins, alkaloids, and saponins. Furthermore, the antioxidative potential of the extract was evaluated against the radicals 2,2-azino-bis(3-ethylbenzothiazoline- 6-sulfonic acid) diammonium salt and 2,2-diphenyl-1-pycrylhydrazyl, and there was a progressive reduction of the radicals with increasing doses of the extract. Moreover, a ferric reducing power assay also showed the antioxidant activity of the crude extract as compared to ascorbic acid, a well-known antioxidant. Another significant finding of the study is that the mace extract also considerably inhibits the enzyme xanthine oxidase in a concentration-dependent manner. Our results partially support the use of mace in dietary regimens as a nutraceutical that could serve as a prophylactic strategy or an adjuvant for the prevention and therapy of gout disease.     

Improvement in the remaining activity of freeze-dried xanthine oxidase with the addition of a disaccharide–polymer mixture

In order to improve the remaining activity of a practically important freeze-dried enzyme, xanthine oxidase (XOD), the effects of disaccharide (sucrose and trehalose), polymer (bovine serum albumin: BSA and dextran) and a mixture of them on the loss of XOD activity during freeze-drying and subsequent storage were investigated. All samples were amorphous solids and their glass transition temperatures (T_g) were evaluated by using differential scanning calorimetry. Although dextran showed no stabilizing effect on the freeze-dried XOD, the others protected XOD from the activity loss during freeze-drying to a certain extent. It was found that the mixture of disaccharide (sucrose or trehalose) and BSA improved the XOD activity synergistically. The XOD activity of the samples decreased gradually during storage at a temperature range of between 25 and 60 °C. Samples stored at temperatures below the T_g showed a lower loss of XOD activity than those stored at just the T_g.     

多酚化合物对黄嘌呤氧化酶抑制作用的研究进展

文章主要对近5年来多酚化合物抑制黄嘌呤氧化酶活性、抑制类型及相互作用研究进行了综述,并对其构效关系、结构修饰及金属配合物的开发与应用进行了展望,以期为多酚化合物作为降尿酸食品功能因子和药物的研发提供参考.