动力学分光光度法测定中药多糖对羟自由基的清除率

目的 根据羟自由基与水杨酸(SA)氧化反应的动力学过程,建立动力学分光光度法测定中药多糖对羟自由基(·OH)的清除率。方法 应用紫外分光光度法,建立·OH与SA反应的动力学曲线,根据动力学曲线斜率的变化测定中药陈皮和灵芝多糖对·OH的清除率,并用维生素C进行方法的重复性与可靠性验证。结果 测定陈皮多糖对·OH 的50%清除率(IC50)为232.6 mg·L^-1;灵芝IC50为0.856 1 g·L^-1;维生素C的 IC50为0.254 4 mmol·L^-1,RSD为0.2％(n＝5)。结论 此方法灵敏可靠,可用于中药多糖成分对·OH清除率的测定。     

芦荟大黄素、芦荟素清除氧自由基作用的研究

目的:研究芦荟大黄素和芦荟素对超氧阴离子自由基(O2-.)、羟自由基(.OH)的清除作用。方法:采用邻苯三酚自氧化体系产生(O2-.),研究芦荟大黄素、芦荟素对O2-.的清除作用;利用Fenton反应产生.OH,研究芦荟大黄素、芦荟素对.OH的清除作用;计算表观清除率及IC50,并与特异性清除剂维生素C做比较。结果:芦荟大黄素、芦荟素、维生素C对O2-.的IC50分别为6.8,8.5,11mg.L-1,对.OH的IC50分别为0.24,0.25,9.1mg.L-1,其清除能力芦荟大黄素>芦荟素>维生素C。结论:芦荟大黄素、芦荟素对O2-.、.OH均有较强清除能力,且清除能力与浓度呈明显的量效关系。     

植物活性多糖抗癌活性的研究——抗自由基作用

目的研究当归、鬼臼、黄芪和猫人参多糖对羟自由基的清除作用。方法采用分光光度法测定羟自由基清除率。结果半数抑制浓度(IC50)分别为当归0.4040g/L、鬼臼0.1021g/L、黄芪0.08782g/L和猫人参0.4913g/L。结论4种多糖对羟自由基的清除能力大小依次为黄芪>鬼臼>当归>猫人参,一定浓度范围内清除作用与多糖浓度具有正相关性。     

蒲公英根多糖的抗氧化活性研究

目的:提取蒲公英根中多糖,测定其多糖含量和体外抗氧化作用。方法:超声波协同酶法提取蒲公英根中的多糖,苯酚-硫酸法测定多糖的含量,以维生素C为对照,采用分光光度法测定蒲公英根多糖对OH·和O-2·自由基的抑制作用,HPLC法检测DPPH·的浓度法测定蒲公英根活性多糖清除DPPH·自由基的能力。结果:蒲公英根中的多糖含量为83.31%,清除OH·、O-2·和DPPH·的IC50值分别为:0.047mg/mL,0.01mg/mL,0.154mg/mL。结论:蒲公英根多糖对OH·、O-2·和DPPH·自由基均有良好的清除能力。     

陈皮提取物的抗氧化活性研究

通过乙醇浸提法对陈皮中黄酮类化合物进行提取并对其含量进行测定,进一步通过铁还原能力实验和羟自由基消除率实验测定陈皮中黄酮提取物的抗氧化活性。研究结果表明：陈皮中黄酮化合物的含量达到24.43%,铁还原能力试验表明,陈皮提取物的IC50值为1.354 mg/ml,羟自由基清除率实验表明,当陈皮黄酮提取物的浓度为4 mg/ml时,清除率达到82.56%,其IC50值为1.340mg/ml。并且黄酮类化合物的浓度的增加,其抗氧化活性逐渐增强。     

松花粉抗氧化活性与主要成分的关联分析

目的:研究松花粉的抗氧化活性及其主要有效部位.方法:采用紫外分光光度法测定不同来源松花粉清除DPPH和羟基自由基的能力,及其总黄酮、总甾醇和总多糖的含量,并进行多元相关分析.结果:松花粉提取液对DPPH与羟基自由基均有清除作用,且都呈明显的量效关系;松花粉与破壁松花粉清除DPPH的平均IC50分别为14.86 g·L-1、12.95 g·L-1,清除羟基自由基的平均IC50分别为20.31 g·L-1、3.45 g·L-1;松花粉总黄酮、总甾醇的含量与清除DPPH自由基、羟基自由基的IC50呈负相关,并以总黄酮的相关性最为突出,而总多糖的含量则与其关联性不显著.结论:松花粉具有一定的抗氧化活性,其有效部位为黄酮和甾醇;松花粉破壁能有效提高其清除自由基的能力及总黄酮、总甾醇的含量.     

马齿苋多糖清除羟自由基作用的研究

目的检测马齿苋多糖清除羟自由基作用。方法利用热水提取乙醇沉淀法制得马齿苋多糖,用分光光度法检测马齿苋多糖对1,1-二苯基-2-苦肼基自由基（DPPH？）,羟自由基（OH？）和超氧阴离子自由基（O2-1）的清除能力。结果与结论马齿苋多糖溶液对DPPH？自由基、OH？和O2-1均具有良好的清除作用,作用随剂量增加而增强。     

分光光度法检测马齿苋多糖的抗氧化活性

目的检测马齿苋多糖抗氧化活性。方法利用热水提取乙醇沉淀法制得马齿苋多糖,用分光光度法检测马齿苋多糖对1,1-二苯基-2-苦味酰基自由基（DPPH.）,羟自由基（OH.）和超氧阴离子自由基（O2-1）的清除能力。结果马齿苋多糖溶液对DPPH.自由基、OH.和O2-1均具有良好的清除作用,作用随剂量增加而增强。结论马齿苋多糖具有很大的开发利用前景。     

四物口服液对羟基自由基的清除作用

目的 评价四物口服液体外对羟基自由基的清除作用.方法 采用荧光分光光度法,过氧化氢溶液与不同浓度的四物口服液稀释、混匀,254 nm紫外光照射后加入苯甲酸溶液,室温放置后在激发波长304 nm、发射波长401 nm条件下测定荧光强度,用羟基自由基清除率IC50（荧光强度降低50％时药物浓度）作为四物口服液对羟基自由基清除率大小的评价指标.结果 四物口服液体外对羟基自由基清除率IC50为0.009 3倍原药.结论 四物口服液具有体外清除羟基自由基的作用.     

芙蓉菊多糖体外抗氧化活性研究

目的研究芙蓉菊多糖的体外抗氧化活性。方法采用1,1-二苯基苦基苯肼(DPPH)自由基、还原力、超氧阴离子、羟自由基4种体外抗氧化模型研究芙蓉菊多糖的抗氧化活性,用维生素C作对照。结果芙蓉菊粗多糖对DPPH自由基、还原力、超氧阴离子、羟自由基均有明显的清除能力,其中DPPH、超氧阴离子、羟自由基的EC50值分别为0.273、0.669、0.594mg/mL,对羟自由基清除能力强于维生素C。芙蓉菊多糖对自由基清除率与其质量浓度存在着明显的量效关系。结论芙蓉菊多糖具有良好的体外抗氧化活性,作为天然抗氧化剂和自由基清除剂有进一步研究的价值。     

八角多糖体外抗活性氧自由基作用的研究

目的提取八角多糖,并测定多糖含量和进一步研究其抗活性氧自由基的能力。方法采用热水浸提法及醇沉法提取八角多糖并利用Sevage法脱蛋白对其进行纯化;用苯酚-硫酸法测定经纯化后的八角多糖样品中纯多糖的含量。最后采用水杨酸法和邻苯三酚自氧化法分别研究八角多糖清除·OH自由基和O2-·自由基的效果。结果八角提取纯化后的多糖样品中纯多糖含量达1.34%。结论八角多糖清除O2-·自由基和·OH自由基的能力均较强。     

The kinetics of elimination of salicylic acid and the formation of gentisic acid

1. A method for the estimation of gentisic acid in urine has been devised which is based on thin-layer chromatography and fluorimetry.2. In man the urinary excretion of gentisic acid accounted for 0.6% of a 0.32 g dose of aspirin and 1.1% of a 1.28 g dose. The increase in the percentage of the dose excreted as gentisic acid provides further evidence that the elimination of salicylic acid cannot be entirely described by first order kinetics.3. Equations are presented which describe the amount of gentisic acid formed from various doses of salicylic acid in a model system, when elimination proceeds partly by simultaneous first order and zero order kinetics. The close agreement of the experimental and theoretical results indicates that the model provides an acceptable interpretation of salicylic acid elimination in man.     

5-硝基水杨酸合成新工艺

目的:采用新方法合成5-硝基水杨酸。方法:以水杨酸为原料,采用硝酸脲/硫酸为硝化试剂,反应得到5-硝基水杨酸以收率为指标考察了反应条件包括硝酸脲/水杨酸物料配比、反应温度、反应时间对反应的影响。结果:得到适合的反应条件为硝酸脲/水杨酸(摩尔比)=1.2:1,反应温度25℃,反应时间6 h,收率为86.4%。结论:新方法收率较高,反应条件温和,适合工业化生产。     

Quantitation of the hydroxyl radical adducts of salicylic acid by micellar electrokinetic capillary chromatography: oxidizing species formed by a Fenton reaction

There has been controversy concerning the products formed by a Fenton reaction. We determined the hydroxyl radical (^.OH) generated in a Fenton reaction system with no iron chelator using micellar electrokinetic capillary chromatography (MECC). The hydroxyl radical generated in this Fenton system attacked salicylic acid to produce major products of 2,3- and 2,5-dihydroxybenzoic acid (DHB), 2,3-DHB being prominent. Hydroxyl radical scavengers, such as mannitol, ethanol, thiourea and a ferric chelator, Desferal, significantly diminished the peaks for DHBs, showing production of ^.OH. We compared the MECC method with the electron paramagnetic resonance (EPR) spin trapping technique. The quantity of DHBs obtained by MECC increased dose-dependently up to 1 μM Fe²⁺ at a fixed concentration of H₂O₂, whereas that of the spin adduct by EPR showed a bell-shaped curve. This quantitation of ^.OH adducts by MECC supports the proposal that the oxidizing species formed by a Fenton reaction with no chelator is ^.OH. The EPR spin trapping method appears to be erroneous, particularly when iron is present at a higher concentration than hydrogen peroxide. The application of this method to the paraquat effect in vitro is demonstrated, and the possibility for analysis of ^.OH in vivo is also discussed. Received: 7 February 1994/Accepted: 12 April 1994     

The effect of cimetidine on the pharmacokinetics of salicylic acid

The pharmacokinetics of the interaction between salicylic acid and cimetidine was investigated in 11 healthy male and female volunteers. The plasma concentrations of total and free salicylic acid were measured. The kinetic disposition of salicylic acid after multiple administration of cimetidine (1 g per day) showed two modifications: the elimination rate was slower and plasma clearance was reduced. The corresponding area under concentration-time curves was always significantly greater. These differences were the same in both sexes. The rate of absorption, peak salicylate concentration and plasma protein binding of salicylic acid in the presence of cimetidine were not changed.     

Drug interaction. Effects of salicylate on pharmacokinetics of valproic acid in rats

The effects of salicylic acid on the pharmacokinetics of valproic acid were investigated in bile-exteriorized rats. A 50 mg/kg bolus dose of sodium valproate was injected iv to Long Evans rats with and without (control) prior treatment by constant infusion of salicylate to keep it at steady state plasma level (about 250 micrograms/ml). The plasma elimination of valproic acid followed a monoexponential decline in both salicylate-treated and control rats. A significant increase (p less than 0.01) in the disposition rate constant (kel), the volume of distribution (Vd), and the total clearance (Cltot) as well as a significant decrease (p less than 0.01) in the AUC and the elimination half-life (t1/2) were observed in the salicylate-treated rats. In spite of the significantly lowered total plasma level and increased unbound fraction of valproic acid in the salicylate-treated rats, there were no significant differences in unbound valproic plasma levels and unbound valproate pharmacokinetic parameters. The biliary excretion of unchanged and conjugated valproate was not significantly different between the two groups. The in vitro plasma-unbound fractions (fu) of valproic acid were significantly increased (p less than 0.01) in the presence of salicylic acid. The apparent dissociation constant of plasma protein binding for valproic acid was increased from 0.287 to 1.204 mM in the presence of salicylic acid. These findings indicate that the pharmacokinetic changes of valproic acid in the presence of salicylic acid were consistent with the elevation in the plasma-unbound fraction of valproic acid due to displacement from plasma protein-binding sites by salicylic acid.(ABSTRACT TRUNCATED AT 250 WORDS)     

Pharmacokinetics of salicin after oral administration of a standardised willow bark extract

OBJECTIVE: To evaluate the pharmacokinetics of salicin and its major metabolites in humans after oral administration of a chemically standardised willow bark extract. METHODS: Willow bark extract corresponding to 240 mg salicin (1,360 mg, 838 micromol) was ingested by ten healthy volunteers in two equal doses at times 0 h and 3 h. Over a period of 24 h, urine and serum levels of salicylic acid and its metabolites, i.e. gentisic acid and salicyluric acid, were determined using reverse-phase high-performance liquid chromatography. Renal excretion rate, elimination half-life and total bioavailability of salicylates were calculated. RESULTS: Salicylic acid was the major metabolite of salicin detected in the serum (86% of total salicylates), besides salicyluric acid (10%) and gentisic acid (4%). Peak levels were reached within less than 2 h after oral administration. Renal elimination occurred predominantly in the form of salicyluric acid. Peak serum levels of salicylic acid were on average 1.2 mg/l, and the observed area under the serum concentration time curve (AUC) of salicylic acid was equivalent to that expected from an intake of 87 mg acetylsalicylic acid. CONCLUSION: Willow bark extract in the current therapeutic dose leads to much lower serum salicylate levels than observed after analgesic doses of synthetic salicylates. The formation of salicylic acid alone is therefore unlikely to explain analgesic or anti-rheumatic effects of willow bark.     

HPLC法测定苯甲酸软膏中水杨酸的含量

目的建立一种快速的用高效液相色谱法测定苯甲酸软膏中水扬酸（SA）的含量。方法使用C18色谱柱,流动相为甲醇：水（60：40,v/v）,检测波长为278nm。结果水杨酸在30～240μg/ml浓度范围内,r=0.9997,平均回收率为99.72%,RSD=0.75%。结论该法可快速准确的测定医用苯甲酸软膏中水杨酸的含量。     

苯酚-硫酸法测定猕猴桃根中多糖含量

目的：建立猕猴桃根中多糖含量的测定方法。方法：用水提醇沉法从猕猴桃根中提取多糖;采用苯酚-硫酸法测定其含量,并通过正交试验,确定最佳显色条件。结果：最佳显色条件为：5％苯酚1mL,浓硫酸4mL,反应温度100℃,反应时间30min。最大吸收波长（λmax）为486．8nm,平均回收率为102．49％,RSD为1．51％,线性范围为20．35～101．90mg·L^-1（r=0．9999）。结论：该法快速、准确、重复性好,可用于以多糖为有效成分的药物的质量控制。     

阿斯匹林与烟酸联合应用时血药浓度测定

阿斯匹林与烟酸给家兔同时ⅳ后,采用新建立的溶剂萃取,分光光度法和Carlson法分别测定两药血浆浓度。结果用微机分析拟合曲线,符合二室开放模型。两药联合应用后,烟酸T_1/2β(2.3374 h)和AUC(361.63μg·h/ml)较单用炳酸时T_1/2β(0.9846h)和AUC(157.71μg·h/ml),差异非常显著(P<0.01)。其它参数在两种情况下均无显著差别。