RP-HPLC法测定熊去氧胆酸胶囊中熊去氧胆酸及有关物质的含量

目的建立反相高效液相色谱法(RP-HPLC)测定熊去氧胆酸胶囊中熊去氧胆酸、胆酸、鹅去氧胆酸及胆石酸的含量。方法使用Diamonsil C18色谱柱(200 mm×4.6 mm,5μm),流动相为乙腈-0.03 mol·L-1磷酸溶液(体积比为40∶60),流速为1.4 mL·min-1,检测波长为205 nm,柱温为35℃。结果熊去氧胆酸胶囊中熊去氧胆酸、胆酸、鹅去氧胆酸及胆石酸在25 min内洗脱并基线分离。熊去氧胆酸、胆酸、鹅去氧胆酸及胆石酸的线性范围分别为0.80²00.00、0.45200.00、0.45¹10.00、0.30110.00、0.30⁷0.00和0.3070.00和0.30⁸0.00 mg·L-1,平均回收率分别为99.7%、99.3%、98.7%和99.1%,RSD分别为1.30%、1.47%、1.87%和1.95%(n=3)。结论 RP-HPLC可用于同时测定熊去氧胆酸胶囊中熊去氧胆酸、胆酸、鹅去氧胆酸及胆石酸的含量,可应用于熊去氧胆酸胶囊胶囊制剂的质量控制。     

咖啡酸、阿魏酸和香草酸对酪氨酸酶活性的影响

目的 :研究咖啡酸、阿魏酸和香草酸对酪氨酸酶活性的影响 ,寻找酪氨酸酶抑制剂 ,从而为治疗色素增加性皮肤病筛选药物。方法 :酪氨酸酶多巴速率氧化法体外测定药物干预前后酪氨酸酶活性 ,求出酪氨酸酶抑制率。采用Lineweaver Burk双倒数法制得酶动力学曲线 ,推断抑制类型。结果 :3种试药中仅香草酸对酪氨酸酶具有抑制作用 ,与氢醌比较无显著差异 (P >0 .0 5 ) ,咖啡酸、阿魏酸对酪氨酸酶具有上调激活作用。结论 :香草酸为良好的混合型酪氨酸酶抑制剂。     

Nalidixic acid prodrugs: Amides from amino acid ester and nalidixic acid

Amides from amino acid ester and nalidixic acid were synthesized. The solubility characteristics and partition coefficient of the compounds were studied. The hydrolysis of the compounds was studied in the simulated gastric fluid and simulated intestinal fluid. Some compounds showed better antibacterial activity than nalidixic acid.     

Carnitine and glucuronic acid conjugates of pivalic acid

The [1-14C]pivaloyloxyethyl ester of methyldopa administered to man and cynomolgus monkeys resulted in the elimination in the urine of 14C-pivalic acid metabolites. Pivaloyl glucuronide and pivaloyl carnitine were identified as the major radioactive urinary metabolites in monkey urine and human urine, respectively. N.m.r. analysis indicated that pivaloyl carnitine had a cyclic structure. Although the role of carnitine is in the transport of fatty acids across mitochondrial membranes, it may also function in the conjugation of carboxylic acid xenobiotics in humans.     

甘露醇-旋光法测定鞣柳硼三酸散中硼酸的含量

目的建立旋光法测定鞣柳硼三酸散中硼酸的含量。方法以低浓度明胶溶液提取制剂中硼酸,利用甘露醇结合硼酸形成具有旋光性复合物,并建立鞣柳硼三酸散中硼酸的含量测定方法。结果硼酸浓度在5～20 g.L-1的浓度范围内与旋光度线性关系良好(r=0.999 2),方法的平均回收率为99.98%,RSD为1.3%。结论旋光法测定鞣柳硼三酸散中硼酸的含量,操作简便、快速,结果准确,重现性好。     

Carnitine and glucuronic acid conjugates of pivalic acid

1. The [1-¹⁴C]pivaloyloxyethyl ester of methyldopa administered to man and cynomolgus monkeys resulted in the elimination in the urine of ¹⁴C-pivalic acid metabolites.

2. Pivaloyl glucuronide and pivaloyl carnitine were identified as the major radioactive urinary metabolites in monkey urine and human urine, respectively.

3. N.m.r. analysis indicated that pivaloyl carnitine had a cyclic structure.

4. Although the role of carnitine is in the transport of fatty acids across mitochondrial membranes, it may also function in the conjugation of carboxylic acid xenobiotics in humans.     

Interaction between activated nordihydroguaiaretic acid and deoxyribonucleic acid

Nordihydroguaiaretic acid (NDGA) is a natural product of the lignan family that has been shown to possess antimicrobial and antineoplastic properties in a variety of test systems. NDGA was observed by u.v.-visible spectroscopy to be unstable in an aqueous environment; however, by these same techniques NDGA was shown to be stable in the presence of mercaptoethanol. It is suggested that an activated NDGA is an intermediate in the O₂-mediated oxidation of NDGA and that the activated NDGA forms a stable complex when reacted with duplex DNA. This DNA-activated NDGA complex was detected and studied by both fluorescence spectroscopy and CsCl density gradient techniques. The addition of DNA quenched the fluorescence of activated NDGA in a concentration-dependent fashion. Furthermore, the exposure of activated NDGA lowered the buoyant density of DNA, also, in a concentration-dependent manner. Since mononucleotides did not quench the fluorescence of activated NDGA, and heat-denatured DNA was less effective than fully duplex DNA in its ability to interact with activated NDGA, the duplex structure of DNA was determined to be important in the complex formation. Whereas activated NDGA bound to both poly dG · poly dC and poly (dA · dT), there appeared, by one method of analysis, to be a preference for poly dG · poly dC. Activated NDGA-DNA complex was stable to dialysis, but dissociated in the presence of Sarkosyl. No changes in the viscosity or melting temperature of DNA was induced by the addition of activated NDGA. These data suggest a mechanism in which the activated NDGA was bound to the more apolar regions of duplex DNA that are located in either the major and/or minor grooves.     

高效液相色谱法测定复方苯甲酸乳膏中苯甲酸和水杨酸的含量

目的:建立高效液相色谱法(HPLC)测定复方苯甲酸乳膏中苯甲酸和水杨酸的含量。方法:色谱柱为Hypersil C_(18)柱(4.6nm×250mm,5μm),流动相为甲醇-水(44:56),流速0.8mL·min~(-1),检测波长为226nm。结果:苯甲酸和水杨酸分别在15.20～76.00mg·L~(-1)和7.64～38.20mg·L~(-1)范围内线性良好(r=0.9999);日内、日间RSD在0.030～4.79％,高、中、低浓度回收率在98.54％～101.20％。分析了3批样品,结果满意。结论:本方法简便,快速,准确,可作为复方苯甲酸乳膏的质量控制方法。     

双波长薄层扫描法测定苯甲酸复方制剂的含量

本文采用硅胶HF_(254 366)薄层板,以氯仿—丙酮—异丙醇—甲醇—浓氨水(30:30:15:15:10)为展开剂,直接分离苯甲酸复方制剂中的苯甲酸与水杨酸。在CS-930型双波长薄层扫描仪上,采用反射式锯齿扫描,分别对苯甲酸和水杨酸进行扫描测定。结果:苯甲酸与水杨酸的线性关系、精度及回收率都比较满意。     

Methylated eicosapentaenoic acid and tetradecylthioacetic acid: effects on fatty acid metabolism.

We introduced methyl or ethyl groups to the 2- or 3-position of the eicosapentaenoic acid (EPA) molecule to investigate whether the branching of EPA could influence its hypolipidemic effect in rats. The most effective branching involved two methyl groups in the 2-position and one methyl group in the 3-position. These EPA derivatives increased hepatic mitochondrial and peroxisomal beta-oxidation and decreased plasma lipids concomitant with suppressed acetyl-coenzyme A (CoA) carboxylase (EC 6.4.1.2) and fatty acid synthase (EC 2.3.1.85) activities. This was followed by elevated activities of camitine O-palmitoyltransferase (EC 2.3.1.21) and possibly 2,4-dienoyl-CoA reductase (EC 1.3.1.34), as well as induced mRNA levels of these enzymes and fatty acyl-CoA oxidase. The fatty acid composition in liver changed, with an increased 18:1 n-9 content, whereas the expression of delta9-desaturase remained unchanged. We investigated the flux of fatty acids in cultured hepatocytes, and found that oxidation of [1-14C]-labeled palmitic acid increased but the secretion of palmitic acid-labeled triglycerides decreased after addition of 2-methyl-EPA. The fatty acyl-CoA oxidase (EC 1.3.3.6) activity in these cells remained unchanged. A significant negative correlation was obtained between palmitic acid oxidation and palmitic acid-labeled synthesized triglycerides. To investigate whether the hypolipidemic effect occurred independently of induced peroxisomal beta-oxidation, we fed rats 2-methyl-tetradecylthioacetic acid. This compound increased the peroxisomal but not the mitochondrial beta-oxidation, and the plasma lipid levels were unchanged. In conclusion, EPA methylated in the 2- or 3-position renders it more potent as a hypolipidemic agent. Furthermore, this study supports the hypothesis that the mitochondrion is the primary site for the hypolipidemic effect.     

Antioxidant and prooxidant activities of alpha-lipoic acid and dihydrolipoic acid

Reactive oxygen (ROS) and nitrogen oxide (RNOS) species are produced as by-products of oxidative metabolism. A major function for ROS and RNOS is immunological host defense. Recent evidence indicate that ROS and RNOS may also function as signaling molecules. However, high levels of ROS and RNOS have been considered to potentially damage cellular macromolecules and have been implicated in the pathogenesis and progression of various chronic diseases. alpha-Lipoic acid and dihydrolipoic acid exhibit direct free radical scavenging properties and as a redox couple, with a low redox potential of -0.32 V, is a strong reductant. Several studies provided evidence that alpha-lipoic acid supplementation decreases oxidative stress and restores reduced levels of other antioxidants in vivo. However, there is also evidence indicating that alpha-lipoic acid and dihydrolipoic acid may exert prooxidant properties in vitro. alpha-Lipoic acid and dihydrolipoic acid were shown to promote the mitochondrial permeability transition in permeabilized hepatocytes and isolated rat liver mitochondria. Dihydrolipoic acid also stimulated superoxide anion production in rat liver mitochondria and submitochondrial particles. alpha-Lipoic acid was recently shown to stimulate glucose uptake into 3T3-L1 adipocytes by increasing intracellular oxidant levels and/or facilitating insulin receptor autophosphorylation presumably by oxidation of critical thiol groups present in the insulin receptor beta-subunit. Whether alpha-lipoic acid and/or dihydrolipoic acid-induced oxidative protein modifications contribute to their versatile effects observed in vivo warrants further investigation.     

Oral antipyretic therapy: Evaluation of the N-aryl-anthranilic acid derivatives mefenamic acid,tolfenamic acid and flufenamic acid

Summary The antipyretic activity of three N-aryl-anthranilic acid derivatives, mefenamic acid, tolfenamic acid and flufenamic acid, was compared and their optimal antipyretic dose determined in a trial in 87 children (aged 5 months to 15 years), who suffered from infections and fever exceeding 38.5°C. Tolfenamic acid proved to be the most potent antipyretic agent of the three drugs; it was eight times more powerful than mefenamic acid and three times more powerful than flufenamic acid. The optimal antipyretic doses were: mefenamic acid 4 mg/kg, tolfenamic acid 0.5 mg/kg and flufenamic acid 1.5 mg/kg. It is evident that the antipyretic activity of these anthranilic acid derivatives is even greater than their antirheumatic effect, the difference being most noticeable in the case of tolfenamic acid.