尿酸酶-过氧化氢酶脂质体的特性分析及药效学研究

目的考察尿酸酶-过氧化氢酶脂质体(uricase and catalase liposome,UCALP)、游离尿酸酶(uricase,UAE)的最适温度和最适pH,并探究UCALP降低高尿酸血症小鼠的尿酸水平和过氧化氢水平的能力。方法采用逆向蒸发法制备UCALP,并分别测定UCALP和UAE的最适温度和最适pH;小鼠腹腔注射尿酸建立高尿酸血症模型后,分别静脉注射UCALP和UAE,用测试盒分别测定不同时间点小鼠血清中尿酸浓度和过氧化氢的浓度。结果 UCALP和UAE的最适温度均为40℃,最适pH分别为8.0和8.5;在高尿酸血症的小鼠体内,UCALP比UAE降尿酸水平更明显,且UCALP组小鼠体内的过氧化氢浓度较UAE组低。结论UCALP能有效降低高尿酸血症小鼠的尿酸水平,且能在一定程度上降低过氧化氢的浓度。     

尿酸酶-过氧化氢酶复合纳米脂质体对高尿酸血症小鼠的治疗作用

目的 考察硼酸-硼砂缓冲液制备的尿酸酶(UA)-过氧化氢酶(CA)复合纳米脂质体(UCLP)对高尿酸血症小鼠的治疗作用.方法 采用pH8.5的硼酸-硼砂缓冲液,运用逆向蒸发法制备UCLP,并考察测定UCLP中UA的最适温度和最适pH;建立小鼠高尿酸血症模型后,给予UCLP治疗,用相应试剂盒测定小鼠体内尿酸和过氧化氢的浓度.结果 UCLP中UA的最适温度为40℃,最适pH为8.0;UCLP组小鼠体内尿酸和过氧化氢的浓度均较UA组低.结论 UCLP能有效降低高尿酸血症小鼠体内的尿酸水平,同时降低体内过氧化氢的浓度.     

青霉素酰化酶提取及其与固定化酶的动力学参数测定和比较

采用冻融-溶媒法从大肠杆菌中提取青霉素酰化酶(经硫酸铵沉淀、透析、冷冻干燥),制得酶粉,活力为1100.37u/g,经六批提取试验,平均提取收率47.93％。分别测定游离酶及其固定化酶米氏常数Km值。游离酶的Km值为2.39mM,固定化酶按其颗粒大小不同,Km值分别为5.62、8.46、8.42mM。 在对pH稳定性测定中,游离酶最适pH为7～8,而固定化后在pH5～9之间都较稳定。对温度的稳定性测定中,游离酶与固定化酶在40℃以下都较稳定,但在45℃保温一小时后,游离酶只存留活力39.51％,而固定化酶却存留活力86.92％,二者有显著差异、温度再高相差更大。因此酶经固定化后,对pH和温度的稳定性都有明显提高。金属离子对青霉素酰化酶的活力有所影响。特别是铁离子和铜离子影响较大,故酶反应容器不能采用铁和铜的材料。     

固定化β-葡萄糖苷酶制备人参皂苷F_1的研究

本文探讨了β-葡萄糖苷酶的固定化方法,及利用固定化β-葡萄糖苷酶转化人参皂苷Rg1为人参皂苷F1的转化工艺。确定交联-包埋法为最佳固定化方法,应用正交实验得出最佳制备条件为:交联时间3h,戊二醛浓度0.1%,海藻酸钠浓度1%,CaCl2浓度2%。固定化酶与游离酶在热稳定性和pH值稳定性方面显示出不同的性质,其中固定化β-葡萄糖苷酶的最适反应温度为70℃,最适反应pH值为5.5。固定化β-葡萄糖苷酶在15℃环境中保存30d后,酶活回收率为68.82%。固定化β-葡萄糖苷酶转化人参皂苷Rg1为人参皂苷F1的转化条件为:固定化酶承载量为3.76U/g固定化酶载体,底物浓度为0.2mg/mL,转化温度为40℃,转化周期为2d,转化次数为4次,平均转化率为80.49%。     

壳聚糖固定化酵母蔗糖酶的研究

用壳聚糖作吸附剂、戊二醛作交联剂,对酵母蔗糖酶进行固定化研究,同时用琼脂糖固定化的蔗糖酶和游离酶与其进行比较。结果表明,壳聚糖固定化蔗糖酶贮藏稳定性、对变性剂以及对温度的耐受性均明显优越,而Km值与琼脂糖固定化酶相当,但比游离酶明显增高,酶的最适pH三者相近。研究表明,壳聚糖固定化酶所需的戊二醛浓度为0.6%,交联时间不低于6 h。固定化蔗糖酶对变性剂(乙醇、脲)的耐受力明显高于游离酶。     

用CHITOSAN固定化青霉素酰化酶

本文报道以Chitosan为载体制备固定化青霉素酰化酶的研究结果。1.4％ Chitosan醋酸溶液先用12.5％戊二醛交联,洗涤,研磨,得颗粒。再用1.5％pH5.5和1.5％pH8.5多聚磷酸处理,得机械强度良好的载体。此载体先后经0.5％戊二醛和对甲苯磺酰氯双活化后,再与青霉素酰化酶偶联。所得固定化酶的活力达20.8u/g。固定化青霉素酰化酶的反应最适温度略高于游离酶,最适pH略低于游离酶;其Km值基本接近游离酶。固定化酶经反复使用,活力基本不变。     

50%硫酸镁溶液中过氧化氢稳定性的影响因素分析

目的:考察pH值和加入不同浓度金属离子络合物乙二胺四乙酸二钠(EDTA-Na2)对50%硫酸镁溶液中过氧化氢稳定性的影响,为过氧化氢作为防腐剂使用提供试验依据。方法:在pH值3.69、3.80、4.02、4.77、6.40、6.81和加入EDTA-Na20.01%、0.02%、0.04%、0.08%、0.16%的条件下,测定2厂家50%硫酸镁溶液中过氧化氢在贮存60d过程中的含量变化,分析pH值和EDTA-Na2对过氧化氢稳定性的影响。结果:不同pH值条件下过氧化氢贮存5d后含量均为0;加入0.04%以下浓度的EDTA-Na2贮存60d后过氧化氢含量均为0,加入0.04%以上浓度的EDTA-Na2贮存60d后过氧化氢的含量均约为50%。结论:溶液pH值对过氧化氢无稳定作用,加入EDTA-Na2对过氧化氢有一定的稳定作用。     

透明质酸酶催化透明质酸水解的最适反应条件

目的确定透明质酸酶(HAase)催化透明质酸(HA)水解的最适条件。方法HAase不同条件下催化HA水解,反应结束后利用高效凝胶渗透色谱(HPGPC)法测量反应产物的相对分子质量及其分布系数。结果HAase催化HA水解受温度、pH值、酶浓度、底物浓度、反应时间等因素的影响。结论HAase催化HA水解的最适反应条件是底物浓度为10 g/L,酶浓度为150 000 U/L,pH为5.0,反应温度为50℃。     

天冬酰胺酶-吴茱萸碱核壳型脂质纳米粒的药动学研究

目的考察天冬酰胺酶-吴茱萸碱核壳型脂质纳米粒(asparaginase-evodiamine core-shell lipidic nanoparticles,AELNs)在大鼠体内的药动学行为,比较AELNs与游离天冬酰胺酶(asparaginase,ASNase)/吴茱萸碱(evodiamine,EVO)的生物利用度。方法取18只SD大鼠,分别尾静脉注射AELNs、游离ASNase和游离EVO,给药后于不同时间点大鼠眼眶取血,分别采用Nessler试剂比色法和HPLC法测定血浆样品中ASNase和EVO的浓度,采用DAS(2.1.1版)软件计算药动学参数。结果将游离ASNase制备成AELNs后,其药时曲线下面积和平均滞留时间分别提高了1.83倍和1.94倍。AELNs中EVO的药时曲线下面积约为游离EVO的28.94倍。结论 AELNs提高了ASNase和EVO在大鼠体内的生物利用度。     

载门冬酰胺酶的自组装聚乙二醇-透明质酸/二甲基-β-环糊精纳米粒体外稳定性的初步考察

采用聚乙二醇接枝透明质酸和二甲基-β-环糊精制备了含载门冬酰胺酶(1)的自组装纳米粒(THDCD),并比较其与游离1在体外的活性及稳定性.测定了THDCD和1的最适温度、最适pH值,并对比了二者的酸碱稳定性、热稳定性、贮存稳定性、血浆稳定性、抗胰蛋白酶水解能力、抗部分金属离子及有机化合物影响的能力.结果表明,THDCD的最适温度和最适pH值为50℃和pH 6.5,而1为60℃和pH 7.5.THDCD的上述稳定性和抗性均优于1.本试验表明,THDCD在提高了1体外活性的同时,也显著增强了1的体外稳定性.     

Transformation of 2,2'-anhydro-1-beta-D-arabinofuranosylcytosine induced by hydrogen peroxide.

2,2'-Anhydro-1-beta-D-arabinofuranosylcytosine (I) is a more potent and less toxic antineoplastic agent than is cytarabine (1-beta-D-arabinofuranosylcytosine) (II). The anhydronucleoside (I) was found to be readily transformed by hydrogen peroxide into 2,2'-anhydro-5-hydroxy-1-beta-D-arabinofuranosylcytosine (III) by treatment with 0.025 M hydrogen peroxide at a neutral and slightly basic pH range (pH 6-9) and at room temperature. It was converted into non-UV-absorbing substance(s) by hydrogen peroxide at an alkaline pH (pH 11). Since hydrogen peroxide is produced by redox reactions in all living cells, it may be responsible for the alteration of I. Such transformations by hydrogen peroxide were not observed with cytarabine.     

Stability of ricobendazole in aqueous solutions

The chemical stability of ricobendazole (RBZ) was investigated using a stability-indicating high performance liquid chromatographic (HPLC) assay with ultraviolet detection. The degradation kinetics of RBZ in aqueous solution was evaluated as a function of pH, buffer strength and temperature. The oxidation reaction in hydrogen peroxide solution was also studied. Degradation products were analyzed by mass spectroscopy and degradation pathways are proposed. Degradation of RBZ followed pseudo first-order kinetics and Arrhenius behavior over the temperature range 24–55 °C. A V-shaped pH-rate profile over the pH range 2–12 was observed with maximum stability at pH 4.8. The shape of the pH-rate profile was rationalized by catalytic effects of various components in the solution on each RBZ species. At pH 11 the activation energy for hydrolysis was 79.5 kJ/mol, and phosphate catalysis was not observed. Oxidation occurred in hydrogen peroxide solutions and was catalyzed by the presence of copper (Cu²⁺) ions. Ricobendazole amine and albendazole sulfone were identified by MS assay to be the degradation products of hydrolysis and oxidation respectively.     

Degradation of microcystin-RR by UV radiation in the presence of hydrogen peroxide.

Experiments were conducted to investigate the degradation of microcystin-RR in order to assess the effectiveness and feasibility of the combined UV/H(2)O(2) catalytic system for purification of water polluted by microcystins. The operating parameters such as hydrogen peroxide dosage, pH value, UV light intensity, initial concentration of microcystin-RR and reaction time were evaluated, respectively. The degradation efficiency increased nonlinearly with increasing UV light intensity and hydrogen peroxide dosage, respectively. There existed an optimal hydrogen peroxide dosage, beyond which the reagent exhibited an inhibitory effect, for degrading microcystin-RR. The degradation process could be fitted by both of the pseudo-first-order and second-order kinetics well and primarily followed a mechanism of both direct photolysis and hydroxyl radical oxidation. Compared with the treatment using UV radiation and hydrogen peroxide individually, the combined UV/H(2)O(2) system could significantly enhance the degradation efficiency due to the synergetic effect between UV radiation and hydrogen peroxide oxidation. The observed rate constants decreased and the corresponding half-lives prolonged as the concentrations of microcystin-RR increased. The combined UV/H(2)O(2) process provides an effective technology for the removal of microcystins from drinking water supplies.     

过氧化氢酶间接碘量法测定吐温80中过氧化氢的含量

目的:用过氧化氢酶间接碘量法测定吐温80中非法加入的过氧化氢的含量。方法:用过氧化氢酶分解样品中的过氧化氢,通过间接碘量法测定分解前后样品中强氧化物的含量,计算样品中过氧化氢的含量。结果:检测了7个厂家18批吐温80中过氧化氢的含量,所有样品全都检测出含有过氧化氢,最高达到了185.3μg·g-1。结论:作为注射剂常用的药用辅料,吐温80中残留的过氧化氢会对注射剂的安全造成严重影响,利用本法可以简便、快捷的检测出过氧化氢含量。     

Effect of prolonged administration of clofibric acid and di-(2-ethylhexyl)phthalate on hepatic enzyme activities and lipid peroxidation in the rat

Male Sprague-Dawley rats were fed diets containing either 0.5% clofibric acid (CA) or 2% di-(2-ethylhexyl)phthalate (DEHP) for 2 years. Both compounds produced liver enlargement which was accompanied by the formation of liver nodules. Hepatic peroxisomal and microsomal fatty acid oxidising enzyme activities were induced in both large nodules and host tissue (i.e. tissue remaining after removal of large nodules) preparations from CA and DEHP treated rats. In contrast, little change in catalase activity was observed and the activities of cytosolic GSH peroxidase and GSH S-transferases were markedly reduced. Increased lipid peroxidation was observed by measurement of conjugated dienes in host tissue homogenates from CA and DEHP treated rats. Microsomal NADPH-dependent lipid peroxidation was also stimulated. Histological examination revealed extensive lipofuscin deposition in non-nodular, but not in nodular, tissue sections from treated rats. These results demonstrate that prolonged peroxisome proliferation can result in lipid peroxidation and that certain enzymes which metabolise hydrogen peroxide and organic hydroperoxides are either little affected or markedly inhibited.     

不同相对分子质量壳聚糖的制备和部分性质研究

目的制备不同相对分子质量 (Mr)壳聚糖并研究其部分性质。方法在中性条件下 ,用过氧化氢氧化法制备不同Mr 的壳聚糖 ,并进行红外表征、热分析和稳定性等研究。结果探索到制备不同Mr 壳聚糖的最适宜条件。结论壳聚糖经过氧化氢降解后 ,结构没有明显变化 ,且随壳聚糖Mr 的降低 ,其稳定性增强     

用过氧化氢对野菊花碱溶性多糖进行脱色的工艺研究

目的 脱除野菊花碱溶性多糖液中的色素.方法 选择过氧化氢(H2O2)为脱色剂,以脱色时间、脱色温度、pH值和H2O2体积分数为试验因素,进行单因素试验以确定影响因素及其水平,采用L9 (34)正交设计进行试验,以多糖保留率、脱色率和蛋白去除率为考察最佳脱色工艺的指标.结果 在脱色时间4h、脱色温度60℃、pH=9和H2O2体积分数为8％的脱色条件下,可以有效地脱除野菊花碱溶性多糖的色素.结论 此脱色方法简单有效.     

甘草酸二铵磷脂复合物注射液的初步稳定性研究

目的制备合适的甘草酸二铵磷脂复合物注射液,并考察其初步稳定性。方法以粒径、过氧化值、pH为指标,分别考察了不同种类溶媒和pH值对注射液稳定性的影响。通过影响因素实验的结果确定最佳处方,并对最适处方进行加速实验。结果以5%葡萄糖注射液为溶媒的处方在高温60℃和强度4 500 Lx光照下放置10 d理化性质没有发生明显变化,且初步加速实验也显示出良好的稳定性。结论甘草酸二铵磷脂复合物葡萄糖注射液质量稳定,粒径符合肝脏靶向性要求。     

Derivative spectrophotometric, thin layer chromatographic-densitometric and high performance liquid chromatographic determination of trifluoperazine hydrochloride in presence of its hydrogen peroxide induced-degradation product.

Three methods are presented for the determination of trifluoperazine HCl in presence of its hydrogen peroxide induced degradation product. The first method was based on measurement of first (1D) and second (2D) derivative amplitudes of trifluoperazine HCl in 0.1 N hydrochloric acid at the zero crossing point of its sulfoxide derivative, main degradation product, (at 268.4 and 262.5 nm for 1D and 2D, respectively). The second method was based on the separation of trifluoperazine HCl from its sulfoxide derivative followed by densitometric measurement of the intact drug spot at 255 nm. The separation was carried out on Merck aluminum sheet of silica gel 60 F(254), using chloroform-methanol (7:3 v/v) as mobile phase. The third method was based on high performance liquid chromatographic separation of trifluoperazine HCl from its sulfoxide derivative on reversed phase, ODS column, using a mobile phase of acetonitrile-phosphate buffer pH 4.2 (60:40 v/v) at ambient temperature. Quantitation was achieved with UV detection at 255 nm based on peak area. The first derivative spectrophotometric method was utilized to investigate the kinetics of the hydrogen peroxide degradation process at different temperatures. The apparent pseudo first-order rate constant, half life and activation energy were calculated.