3,5-O-二咖啡酰基奎宁酸的制备及其对HeLa细胞的抗增殖活性研究

目的 制备高纯度3，5-O-二咖啡酰基奎宁酸，并评价其对人宫颈癌HeLa细胞的抗增殖活性。方法 采用柱色谱提取法和中压液相色谱法从奇蒿花中分离、纯化得到高纯度的3，5-O-二咖啡酰基奎宁酸。采用MTT法评价该化合物对人宫颈癌HeLa细胞的体外抗增殖活性。结果 柱色谱提取的提取率和中压液相色谱法的回收率分别为99.0%，61.2%，总回收率为54.0%。随着3，5-O-二咖啡酰基奎宁酸浓度升高，HeLa细胞存活率下降，细胞形态损伤增加，受试药物的IC₅₀值为26.5µg·mL^-1。结论 本研究提供了一种简单、高效、节能的3，5-O-二咖啡酰基奎宁酸制备方法。3，5-O-二咖啡酰基奎宁酸对HeLa细胞具有一定的体外抗增殖活性。     

HPLC-Q-TOF-MS技术在预知子配方颗粒指纹图谱建立和化学成分归属中的应用

目的 建立预知子配方颗粒的HPLC指纹图谱，并使用Q-TOF-MS技术鉴定共有峰成分。方法 采用Agilent Poroshell 120 EC-C₁₈色谱柱（4.6 mm×50 mm，2.7 mm），以乙腈-0.05%甲酸水溶液为流动相进行梯度洗脱，检测波长210 nm，柱温30℃，流速0.5 mL·min^-1。采用相似度分析软件对指纹图谱进行分析。以标准物质和文献数据为参照，使用Q-TOF-MS负离子检测模式对特征峰进行质谱分析并指认。结果 建立了预知子配方颗粒的HPLC指纹图谱，以4，5-O-二咖啡酰基奎宁酸峰为参照峰，标定了14个共有峰，样品间相似度范围为0.943~0.994，样品与对照指纹图谱相似度范围为0.976~0.988。使用Q-TOF-MS对共有峰进行了指认，确定了8个峰成分，分别为新绿原酸、绿原酸、木通苯乙醇苷B、3，4-O-二咖啡酰基奎宁酸、3，5-O-二咖啡酰基奎宁酸、4，5-O-二咖啡酰基奎宁酸、川续断皂苷Ⅵ、α-常春藤皂苷。结论 该方法灵敏、准确、可靠，可用于预知子配方颗粒的质量评价。     

RP-HPLC法测定眩晕宁颗粒中3,5-O-二咖啡酰基奎宁酸、23-乙酰泽泻醇B和β-蜕皮甾酮

目的 建立RP-HPLC法测定眩晕宁颗粒中3,5-O-二咖啡酰基奎宁酸、23-乙酰泽泻醇B和β-蜕皮甾酮的测定方法。方法 采用Capcell Pak UG C₁₈色谱柱（250 mm×4.6 mm,5 μm）;流动相为乙腈–0.5%磷酸溶液,梯度洗脱;检测波长：348 nm（3,5-O-二咖啡酰基奎宁酸）、250 nm（23-乙酰泽泻醇B）、208 nm（β-蜕皮甾酮）;体积流量：1.0 mL/min;柱温：28℃;进样量：10 μL。结果 3,5-O-二咖啡酰基奎宁酸、β-蜕皮甾酮和23-乙酰泽泻醇B分别在0.076 7～7.670 0、0.098 3～9.830 0、0.019 7～1.970 0 μg/mL线性良好,平均回收率分别为100.05%、98.33%、99.42%,RSD值分别为0.7%、1.2%、1.3%。结论 方法具有前处理简单、分析时间短、检测结果准确等优点,适用于眩晕宁颗粒的质量控制。     

RP-HPLC法同时测定防暑清热饮中5种活性成分的含量

目的 建立RP-HPLC法同时测定防暑清热饮中绿原酸、木犀草素-7-O-β-D-葡糖苷、3,5-O-二咖啡酰奎宁酸、蒙花苷和广藿香酮含量的方法。方法 采用ZORBAX-SB-C₁₈色谱柱(250 mm×4.6 mm,5 μm),以0.2%磷酸溶液（A）-乙腈（B）梯度洗脱,流速为1.0 ml/min,检测波长为327 nm,柱温为30 ℃。结果 绿原酸、木犀草素-7-O-β-D-葡糖苷、3,5-O-二咖啡酰奎宁酸、蒙花苷和广藿香酮线性关系良好（r≥0.999 6）,平均加样回收率（RSD）分别为102.03%（1.63%）、102.38%（1.51%）、102.39%（1.23%）、103.14%（1.87%）和104.01%（2.33%）。结论 本实验建立的测定方法简单、准确、重复性好,能够有效控制该制剂的质量。     

基于体外Pig-a基因突变试验的大黄素型蒽醌致突变风险评价

目的 对相同母核结构的8种大黄素型蒽醌类化合物开展体外Pig-a基因突变试验，分析不同大黄素型蒽醌结构与致突变性的关联。方法 L1578Y细胞分别与系列浓度的大黄素、芦荟大黄素、大黄素甲醚、大黄酚、大黄酸、羟基大黄素、大黄素-8-O-β-D-葡萄糖苷和芦荟大黄素-8-O-β-D-葡萄糖苷作用4 h（有S9）或24 h（无S9），给药24 h后应用细胞计数板进行计数，计算细胞相对倍增速率（RPD）评价受试物细胞毒性；细胞表达8 d后经APC-anti-CD45和PE-anti-CD90.2标定后，使用流式细胞仪检测突变细胞（CD45^＋CD90^－）发生率。结果 所有受试物在有或无S9代谢活化条件下所设浓度组RPD均大于50%，未见明显细胞毒性作用，可排除试验中假阳性结果。在非S9代谢活化条件下芦荟大黄素25 μg·mL^-1组Pig-a基因突变率与溶媒对照组比较显著升高（P<0.001）； S9代谢活化条件下，与溶剂对照组比较，大黄素50 μg·mL^-1组，羟基大黄素6.25、12.5、25 μg·mL^-1组，大黄酚25、50、100 μg·mL^-1组和大黄酸12.5、25、50 μg·mL^-1组Pig-a基因突变率显著升高（P<0.05、0.01、0.001）。结论 羟基取代基的多寡及所在位点是蒽醌类化合物致突变性强弱的决定性因素，其体内致突变性及致癌性作用仍需进行大量体内研究证实。     

畲药树参茎化学成分分析及抗炎活性部位高效液相指纹图谱的建立

目的 对畲药树参茎所含化学成分进行确证分析，并建立抗炎活性部位的高效液相色谱指纹图谱。方法 采用液相色谱-质谱联用、核磁共振波谱仪等分析仪器分离鉴定树参茎中的化学成分；采用高效液相色谱法建立抗炎活性部位指纹图谱：色谱柱为Waters Sunfire^TM C₁₈(4.6 mm×250 mm，5 μm)，流动相为乙腈-混合水溶液(含甲酸0.2%和四氢呋喃0.2%)，梯度洗脱。检测波长为256 nm，柱温30 ℃，体积流量为1.0 mL·mim^–1，分析时间为80 min，进样量为5 μL。结果 从树参茎中共分离鉴定出10个化合物，分别是绿原酸(1)、3,4-O-二咖啡酰基奎宁酸(2)、3,5-O-二咖啡酰基奎宁酸(3)、4,5-O-二咖啡酰基奎宁酸(4)、saikolignanoside A(5)、芦丁(6)、山柰酚-3-O-芸香糖苷(7)、紫丁香苷(8)、松柏醇(9)、芥子醛葡萄糖苷(10)；12批样品抗炎活性部位指纹图谱相似度为0.901~0.992，均符合要求。结论 树参茎中主要含有酚酸类、黄酮类、苯丙素类化合物；建立的指纹图谱不仅能体现树参茎抗炎的化学物质基础，而且鉴别方法简便、重复性好，可为树参茎的品质评价及主要抗炎活性成分的确证提供科学依据。     

基于HPLC-Q-TOF-MS/MS技术咳喘宁颗粒化学成分分析及多指标定量测定

目的 采用高效液相色谱-四极杆飞行时间串联质谱技术（HPLC-Q-TOF-MS/MS）对咳喘宁颗粒化学成分进行分析,并建立 HPLC 多成分含量测定方法。方法 采用 HPLC-Q-TOF-MS/MS 技术,色谱柱 Agilent ZORBAX C₁₈（150 mm×4.6 mm,5 μm）,柱温 35 ℃,体积流量 1.0 mL·min^-1,进样量 10 μL,流动相 A：0.1% 甲酸,流动相 B：乙腈,梯度洗脱;电喷雾离子源（ESI）,正、负离子模式扫描,结合对照品和文献数据鉴定咳喘宁颗粒中的化学成分,并建立HPLC法同时测定新绿原酸、绿原酸、3,5-O-二咖啡酰基奎宁酸、异绿原酸B、4,5-O-二咖啡酰基奎宁酸、柚皮苷的含量。色谱条件：以十八烷基硅烷键合硅胶为填充剂（Waters AtlantisTM T3色谱柱,250 mm×4.6 mm,5 μm）,以甲醇-0.1%甲酸为流动相,梯度洗脱：0～20 min,3%～15% 甲醇;20～25 min,15%～18% 甲醇;25～26 min,18%～23% 甲醇;26～45 min,23%甲醇;45～46 min,23%～38% 甲醇;46～60 min,38% 甲醇;60～61 min,38%～42% 甲醇;61～70 min,42% 甲醇 ;70～80 min,42%～90%甲醇;体积流量1.0 mL·min^-1,柱温30 ℃;进样量10 μL,检测波长324、283 nm。结果 共鉴定咳喘宁颗粒中86个化合物,20个来自生麻黄、15个来自白屈菜、30个来自金银花、22个来自枇杷叶、12个来自金沸草、14个来自化橘红,其中有26个化合物经与对照品比对确认,选择新绿原酸、绿原酸、3,5-O-二咖啡酰基奎宁酸、异绿原酸B、4,5-O-二咖啡酰基奎宁酸和柚皮苷作为含量测定的质控指标,6种成分在各自质量浓度范围内线性关系良好（r≥0.999 9）,精密度、稳定性及重复性良好,加样回收率为99.48%～103.39%,RSD为1.29%～1.98%。对3批咳喘宁颗粒进行多成分含量测定,方法可行。结论 在质谱成分解析的基础上,建立咳喘宁颗粒6种化学成分的含量测定方法,为咳喘宁颗粒的药效物质基础和质量标准研究提供参考。     

UHPLC测定芎菊上清丸中9种成分含量及化学模式分析

目的 建立UHPLC波长切换法同时测定芎菊上清丸中9种成分的含量方法。方法 采用Agilent Ecilipse C₁₈（2.1 mm×100 mm,1.6 μm）色谱柱,流动相：甲醇-0.05%磷酸水溶液,梯度洗脱;流速为0.3 mL·min^-1;检测波长：327,237,320,345,278,254 nm;柱温30℃;进样量2 μL;并采用SPSS 22.0统计软件对含量测定结果进行主成分分析与聚类分析。结果 绿原酸、3,5-二咖啡酰奎宁酸、栀子苷、甘草苷、阿魏酸、盐酸小檗碱、黄芩苷、升麻素苷、5-O-甲基维斯阿米醇苷线性范围分别为4.30~68.80 μg·mL^-1（r=0.999 0）、6.66~106.56 μg·mL^-1（r=0.999 2）、7.67~122.72 μg·mL^-1（r=0.999 4）、4.88~78.08 μg·mL^-1（r=0.999 1）、2.37~37.92 μg·mL^-1（r=0.999 1）、6.50~103.92 μg·mL^-1（r=0.999 2）、8.85~141.60 μg·mL^-1（r=0.999 4）、0.88~14.08 μg·mL^-1（r=0.999 7）、0.74~11.92 μg·mL^-1（r=0.999 3）;平均加样回收率（n=9）均在99.42%~103.10%,RSD均<2.0%。主成分分析与聚类分析均可将不同生产厂家的芎菊上清丸很好地分类,且分类结果一致。结论 所建立的多成分方法快捷、准确、重复性好,可用于芎菊上清丸的质量控制。     

一测多评法在冬菊利咽合剂质量控制中的应用研究

目的 建立一测多评法同时测定冬菊利咽合剂中绿原酸、木犀草苷和3，5-O-二咖啡酰基奎宁酸3种成分的含量。方法 采用HPLC：Agilent TC-C₁₈（2）色谱柱（4.6 mm×250 mm，5 μm），以乙腈-0.1%磷酸水溶液为流动相进行梯度洗脱，流速1.0 mL·min^-1，柱温30℃，检测波长334 nm；以绿原酸为内参物，建立其与木犀草苷、3，5-O-二咖啡酰基奎宁酸之间的相对校正因子（f_s∕i）；采用外标法测定冬菊利咽合剂中绿原酸的含量，通过f_s∕i计算冬菊利咽合剂中其他2种成分的含量，并将一测多评法与外标法测得的实验结果进行t检验，验证一测多评法的准确性。结果 各成分的f_s/i适用性和重复性良好，采用一测多评法和外标法的测定值无显著差异。结论 本实验所建立的一测多评法可用于冬菊利咽合剂的定量分析和质量评价。     

灯盏花中新的酚酸类化合物的结构及活性研究

目的研究中药灯盏花［Erigeron breviscapus (Vant.)Hand-Mazz］的心血管活性成分。方法用各种色谱技术进行分离,用IR,UV,MS,¹HNMR,¹³CNMR,2DNMR光谱鉴定他们的结构。以乳酸脱氢酶(LDH)释放量为指标测定BCMEC(bovinecerebralmicrovascularendothelialcell)损伤,比色法测定药物体外抗氧化和抗活性氧能力。结果从灯盏花中分离得到2个化合物,分别鉴定化合物的结构为：1-O-甲基-3,5-O-双咖啡酰基奎宁酸甲酯(III)和5-O-咖啡酰基奎宁酸丁酯(IV)。结论化合物III,IV为新的酚酸类化合物,化合物III对LPC引起的BCMEC损伤有明显的保护作用。     

Synthesis and evaluation of 2,6-piperidinedione derivatives as potentially novel compounds with analgesic and other CNS activities

New 2,6-piperidinediones 2_a–g and 4_a–d were prepared by initial condensation of aromatic aldehydes or cycloalkanones with cyanoacetamide to give α-cyanocinnamides l_a–g or cycloalkylidenes 3_a,b which underwent Michae1 addition with ethyl cyanoacetate or diethylmalonate. Compounds 4_a–d were alkylated by various alkyl halides to produce the N-alkylated 2,6-piperidinedione derivatives 5_a–m. Some new selected compounds 2_a–c,f, 4_a–d & 5_e,h,j were pharmacologically evaluated for potential anticonvulsant, sedative and analgesic activities. These compounds exhibited significant anticonvulsant and analgesic effects after a single I.P. administration 100 mg/kg b.wt. . On the other hand all the investigated compounds induced hypnotic activity and prolonged the phenobarbital sodium- induced sleep as compared with the control group and the most potent compound was found to be 2_f.     

NEURAMIDE STIMULATES ADRENOCORTICOTROPIN BUT NOT PROLACTIN RELEASE FROM RAT PITUITARY

Neuramide (NMD), a substance found in crude preparations of porcine stomach extract, is a viral inhibitor that also has putative immunostimulatory effects. The effects of NMD on stress-hormone (ACTH and prolactin—PRL) release were assessed inin vivoandin vitrostudies. In the former, blood levels of corticosterone and PRL were measured in NMD-treated male rats.In vitroexperiments were performed to evaluate the effects of NMD and three of its fractions (obtained with high performance liquid chromatography) on ACTH and PRL release from perfused rat pituitary slices. NMD increased plasma corticosterone levelsin vivoand produced dose-dependent increases inin vitropituitary release of ACTH. No effects on PRL secretion were observedin vivoorin vitro. The stimulatory effects on ACTH release were caused by the NMD fraction with a molecular weight of >5000<10000Da.     

鼻渊净胶囊的HPLC指纹图谱研究

目的 建立鼻渊净胶囊的高效液相色谱（HPLC）指纹图谱。方法 采用Agilent SB-C₁₈（4.6 mm×250 mm,5 μm）色谱柱,乙腈-水为流动相、以1.0 ml/min流速行梯度洗脱,检测波长210 nm,柱温30 ℃,洗脱时间为80 min。采用中药色谱指纹图谱相似度评价系统（2004A版）对检测出色谱进行指纹图谱相似度评价。结果 建立了鼻渊净胶囊的HPLC指纹图谱,确定了20个共有峰,15个峰归属到各药材,其中5个峰确认了化学成分;10批样品的指纹图谱的整体相似度与对照图谱比较,均在90%以上。结论 所建立的鼻渊净胶囊指纹图谱有助于从整体上控制该制剂的质量。     

EFFECTS OF 2-GUANIDINE-4-METHYLQUINAZOLINE ON GASTRIC ACID SECRETION IN RATS

In this study 2-guanidine-4-methylquinazoline (2-GMQ) appeared to decrease basal and stimulated gastric acid secretion, while structurally related compounds as dimethyl- biguanide, cyanoguanidine and 2-cyanoamino-4-methylpyrymidine did not. Thus, there is an antisecretory effect when the biguanide group is associated with a lipophilic structure. The antisecretive effects exerted by 2-GMQ are associated with anti H₂-histamine activity.The anti H₂-histamine nature of the effects of 2-GMQ was confirmed by the capacity of this compound of depressing the chronotropic activity of the isolated guinea pig auricle increased by histamine, as well as relaxant activity in rat uterus contracted by histamine, since both preparations are rich in H₂-histamine receptors.     

EFFECT OF POLICOSANOL SUCCESSIVE DOSE INCREASES ON PLATELET AGGREGATION IN HEALTHY VOLUNTEERS

Policosanol is a cholesterol-lowering drug with hypocholesterolemic effects demonstrated in experimental models, healthy volunteers and type II hypercholesterolemic patients. In addition, antiplatelet effects of policosanol have been shown in experimental models and healthy volunteers. The effect of successively increasing doses of policosanol on platelet aggregation was investigated in a randomized, placebo-controlled, double-blind study conducted in 37 healthy volunteers. The volunteers were on a placebo-baseline period (two tablets per day) for 7 days and thereafter they received randomly, under double-blind conditions, placebo or policosanol (10mgday⁻¹) for 7 days. After this period dosage was doubled to 20mgday⁻¹for the next 7 days and then again doubled to 40mgday⁻¹, while the control group received placebo tablets all the time. Platelet aggregation as well as coagulation time was measured at baseline and after each dosing step. Results showed that antiplatelet effects of policosanol were successfully enhanced throughout the study, thus suggesting a dose-dependent relationship. No significant effect was reached during the first dosing period, but significant reductions of epinephrine and ADP-induced platelet aggregation were observed after the second one. Finally, a significant inhibition of platelet aggregation induced by all the agonists was observed at the last dosing step. Coagulation time remained unchanged during the trial.     

Investigation of the prevalence of tetQ, tetX and tetX1 genes in Bacteroides strains with elevated tigecycline minimum inhibitory concentrations

In this study, the antibiotic susceptibilities to tigecycline and tetracycline of 35 selected Bacteroides fragilis group strains were determined by Etest, and the presence of tetQ, tetX, tetX1 and ermF genes was investigated by polymerase chain reaction (PCR). tetQ was detected in all 12 B. fragilis group isolates (100%) exhibiting elevated tigecycline minimum inhibitory concentrations (MICs) (≥8 μg/mL) as well as the 8 strains (100%) with a tigecycline MIC of 4 μg/mL, whilst tetX and tetX1 were present in 15% and 75% of these strains, respectively. All of these strains were fully resistant to tetracycline (MIC ≥ 16 μg/mL). On the other hand, amongst the group of strains with tigecycline MICs < 4 μg/mL (15 isolates), tetQ, tetX and tetX1 were found less frequently (73.3%, 13.3% and 46.7%, respectively). All but two strains harbouring the tetQ gene in this group were non-susceptible to tetracycline, with a MIC > 4 μg/mL. These data suggest that in most cases tigecycline overcomes the tetracycline resistance mechanisms frequently observed in Bacteroides strains. However, the presence of tetX and tetX1 genes in some of the strains exhibiting elevated MICs for tigecycline draws attention to the possible development and spread of resistance to this antibiotic agent amongst Bacteroides strains. The common occurrence of ermF, tetX, tetX1 and tetQ genes together predicted the presence of the CTnDOT-like Bacteroides conjugative transposon in this collection of Bacteroides strains.     

化学—酶法立体控制合成光学纯L-羟基苯丙氦酸的新方法

Optically pure L-3(2-hydroxyphenyl) alanine(L-o-tyrosine ,Ⅲa,),L-3-(3-hydroxyphenyl) alanine(L-m-tyrosine,Ⅲb )and L-3-(4-hydroxyphenyl )alanine(L-p-tyrosine,Ⅲc )were synthesized by the stereocontrolled amination of corresponding hydroxycinnamic acld(Ⅱ)catalyzed by L-phenylalanine ammonia-lyase(PAL,EC4.3.1.5 )contained in Rhodoterula rubramycelium. The amination of compound Ⅱ was completed in aqueous ammonia solution( 6.4mol·L^-1,pH10.5, 30℃) with the conversion of 74.9%(Ⅱa),21.1%(Ⅱb)and 20.6%(Ⅱc)respectively.The absolute configuration of the products Ⅲa～c were confirmed by circular dichroism(CD),and chiral high-performance ligand exchange chromatography(HPLEC)showed that productsⅢ were optically pure L-isomers.     

AMELIORIATION OF CHEMICALLY-INDUCED HEPATOCYTE INJURY BY CYCLOSPORINE A

Cyclosporine A, beside its current applications, possesses potential hepatoprotective effects. This study was directed to investigate the effect of Cyclosporine A pretreatment on hepatic injury due to carbon tetrachloride (CCl₄) and -galactosamine. Rats were injected by two successive doses of Cyclosporine A (5mgkg⁻¹day⁻¹). Six hours after the second dose, 1mlkg⁻¹of CCl₄was administered i.p. Effects associated with Cyclosporine A pretreatment were examined by using isolated hepatocytes and hepatocytes that were immobilized and continuously perfused. -Galactosamine (5m ) was added directly to the perfusion medium. After isolation, hepatocytes were examined histologically by light and electron microscopy, immobilized and perfused for further metabolic functional activity evaluation. Cyclosporine A pretreatmentin vivoproduced hepatoameliorative effects of various degrees which were statistically significant as manifested by: (1) an increased trypan blue exclusion after CCl₄; (2) an improved ureagenesis after CCl₄; (3) a reduction in the lipid droplets accumulation in the cytoplasm produced by CCl₄administration; (4) well preserved cytoplasmic organelles as mitochondria, endoplasmic reticulum ER, nuclear chromatin structures that were altered by CCl₄; and (5) an increased hepatocytes survival in the agarose gel matrix, reduction of LD leakage and improvement of ureagenesis after -galactosamine addition to the perfusion medium. The beneficial effect of Cyclosporine A pretreatment in modifying hepatotoxicity of chemical insults merits further studies.     

喙果黑面神化学成分研究

目的研究大戟科植物喙果黑面神(Breynia rostrata Merr.)的化学成分。方法利用硅胶、凝胶等色谱技术分离纯化化学成分,根据化合物的理化性质和光谱数据进行结构鉴定。结果从喙果黑面神的正丁醇萃取部分分离得到4个化合物,分别鉴定为6-O-甲基丙酰基-α-D-吡喃葡糖(6-O-methylpropanoyl-α-D-glucopyranose,1);4″-苯酚基-6-O-甲基丙酰基-β-D-吡喃葡糖苷(4″-phenolic-6-O-methylpropanoyl-β-D-glucopyranoside,2);1-O-没食子酰基-β-D-吡喃葡糖苷(1-O-galloyl-β-D-glucopyranoside,3);熊果苷(arbutin,4)。结论化合物1和2为新化合物,3和4均为首次从该种植物分离得到。     

INDIRECT PARASYMPATHOMIMETIC ACTIVITY OF THE CLASS III ANTIARRHYTHMIC SUBSTANCE / -SOTALOLIN VITRO: REVERSIBLE INHIBITION OF CHOLINESTERASE ISOENZYMES FROM BLOOD AND THE HUMAN CENTRAL NERVOUS SYSTEM

Inhibitory effects of the class III antiarrhythmic compound / -sotalol on acetylcholinesterase (AChE; EC 3.1.1.7) isoenzymes of both erythrocytes and the human caudate nucleus and on serum cholinesterase (ChE; EC 3.1.1.8) were studiedin vitrousing a spectrophotometric kinetic assay with acetylthiocholine (ASCh) as substrate. Sotalol concentrations in the assays varied from 0.32 to 3.2m . All isoenzymes studied were inhibited by / -sotalol in a reversible and concentration-dependent manner. Double reciprocal plots of the reaction velocity against varying ASCh concentrations revealed that / -sotalol reduced substrate affinity (apparent Michaelis constant, KM, increased) of serum ChE, but did not change the enzyme's maximal rate of ASCh hydrolysis (V_max). Thus, / -sotalol inhibition of serum ChE was of the competitive type (rate constant for reversible competitive inhibition: K_i=0.51m ). In contrast, / sotalol reduced the maximal reaction velocity of the AChE isoenzyme from the central nervous system (caudate nucleus), but had no influence on substrate affinity of the enzyme (K_Mwith ASCh unchanged) indicating purely non-competitive inhibition kinetics (rate constant of reversible non-competitive inhibition: K_i′=0.44m ). / -sotalol inhibition of erythrocyte AChE was of mixed competitive/non-competitive type (K_i=0.31m , K_i′=0.49m ). Non-competitive / -sotalol inhibition of caudate nucleus AChE and the non-competitive component of erythrocyte AChE inhibition cannot be overcome by increased concentrations of the cholinergic transmitter acetylcholine (ACh). Peak / -sotalol plasma levels as described in the literature for both humans (15μ ) and experimental animals (dogs: 18μ ; rats: 260μ ) as well as maximal myocardial concentrations of the substance (dogs: 46μ ; rats: 478μ ) are in the range of about 2% to 100% of the sotalol inhibition rate constants determined in the present paper for cholinesterase isoenzymesin vitro. Thus, / -sotalol inhibition of ACh hydrolysisin vivomay contribute to both the well known antiarrhythmic potential and proarrhythmic side effects of the compound.