甲基莲心碱治疗心血管疾病的药理作用及其机制研究进展

甲基莲心碱是从睡莲科植物莲Nelumbo nucifera成熟种子的胚芽中提取出的一种双苄基异喹啉类生物碱,具有抗动脉粥样硬化、抗高血压、抗血栓、抗糖尿病血管病变和血管保护作用、抗心律失常等作用。心血管疾病是全球发病率和死亡率最高的一类疾病,包括心绞痛、高血压、高血脂、动脉粥样硬化。近年来,有研究表明甲基莲心碱对心血管疾病防治具有疗效好、副作用低的特点。对甲基莲心碱在心血管疾病中的药理作用及其机制进行综述,为甲基莲心碱的药物研发和临床应用提供参考。     

甲基莲心碱的降压作用

甲基莲心碱对麻醉、清醒的正常大鼠,肾性、D0CA盐型高血压大鼠,麻醉猫、清醒正常家兔都能引起快速、剂量依赖性降压作用,猫椎动脉注射及脑室内注射甲基莲心碱0.6mg/kg无明显降压作用。表明甲基莲心碱是一种有效的抗高血压药,对血管平滑肌有直接扩张作用。     

甲基莲心碱对大鼠血压、血小板聚集和血栓形成的影响

采用比浊法研究甲基莲心碱对大鼠血压及血小板聚集、血栓形成的影响，结果显示甲基莲心碱在降低血压的同时，能剂量依赖性地抑制ＡＤＰ和胶原诱导的正常大鼠、肾性高血压大鼠和高脂喂养大鼠血小板聚集；甲基莲心碱亦能明显延长电刺激大鼠颈动脉闭塞性血栓形成时间。此结果表明甲基莲心碱具有降压与抗血小板聚集和血栓形成的双重作用。     

甲基莲心碱小鼠脑内分布的研究

目的：探讨甲基莲心碱在小鼠脑内的分布情况。方法：建立甲基莲心碱的HPLC测定方法,测定小鼠静脉注射不同剂量的甲基莲心碱后不同时间点脑内甲基莲心碱的浓度。结果：甲基莲心碱在0．075—3．2mg·L^-1范围内线形关系良好（r〉0．999）;小鼠脑内检测到甲基莲心碱,且在甲基莲心碱注射20min时脑内浓度达峰值;脑内甲基莲心碱浓度随着给药剂量的增加而增加,30mg·kg^-1给药时脑内甲基莲心碱达峰值。结论：甲基莲心碱能够通过小鼠的血脑屏障分布于脑组织中。     

薄层扫描法测定莲子心中甲基莲心碱及莲心碱含量

目的 :建立测定莲子心中甲基莲心碱及莲心碱含量的方法。方法 :超声提取莲子心中有效成分 ,用薄层扫描法测定其主要成分含量。结果 :甲基莲心碱及莲心碱回收率分别为97 91 %、99 28 % ;相关系数分别为0 996和0 999。结论 :方法简单可靠、重现性好 ,具有良好的线性关系 ,可用于莲子心或其它复方制剂中甲基莲心碱及莲心碱的定量分析。     

甲基莲心碱分子印迹聚合物的制备

目的研究甲基莲心碱分子印迹聚合物的制备。方法采用均匀设计,以甲基莲心碱为模板分子,a-甲基丙烯酸（-αMAA）为功能单体,乙二醇二甲基丙烯酸酯（EDMA）为交联剂,偶氮二异丁腈（AIBN）为引发剂,通过热引发聚合,优化甲基莲心碱分子印迹聚合物的制备条件,并通过固相萃取法检验该聚合物对甲基莲心碱的吸附性能。结果当甲基莲心碱用量为0.1 mmol时,最优制备条件为a-甲基丙烯酸和乙二醇二甲基丙烯酸酯用量分别为0.8 mmol和2.5 mmol,反应温度为50℃。结论用该工艺制备的分子印迹聚合物对甲基莲心碱具有较好的选择性和吸附性。     

甲基莲心碱对大鼠心电图和蟾蜍坐骨神经动作电位的影响

在麻醉大鼠观察了恒速iv甲基莲心碱对ECG的影响,并与奎尼丁和粉防己碱进行了对比性研究。甲基莲心碱对大鼠ECG的影响与奎尼丁相似,剂量(2～40mg/kg)依赖性地延长P-R和Q-T,使QRS增宽;粉防己碱不增宽QRS。结果显示甲基莲心碱作用机理与奎尼丁相似,不同于粉防己碱。甲基莲心碱与奎尼丁都可依浓度抑制蟾蜍坐骨神经APA,二者作用强度相近。     

甲基莲心碱的药理作用研究进展

综述近年来甲基莲心碱的药理学研究进展,甲基莲心碱在增强肿瘤细胞的敏感性方面具有确切的作用且具有一定的开发价值.     

甲基莲心碱对人脐静脉血管平滑肌细胞增殖及表型调节的影响

目的研究甲基莲心碱对人脐静脉平滑肌细胞增殖及表型调节的影响。方法以0.1,0.5,1.0,5.0μmol·L-1甲基莲心碱处理平滑肌细胞,采用MTT法和流式细胞术观察甲基莲心碱对人脐静脉血管平滑肌细胞增殖的影响。用免疫印迹法检测收缩型平滑肌细胞特异性标志物SM1,calponin 1和α-actin蛋白的表达。结果甲基莲心碱（0.1~5.0μmol·L-1）处理12,24,48 h后,人脐静脉血管平滑肌细胞的增殖具有明显的抑制作用,并具有剂量依赖关系和时间依赖关系。在缺乏甲基莲心碱的干预下,血管平滑肌细胞SM1,calponin 1和α-actin蛋白表达减少,在用0.5,5.0μmol·L-1甲基莲心碱处理48 h后,可显著逆转SM1,calponin 1和α-actin蛋白表达的减少,且具有剂量依赖性。结论甲基莲心碱具有抑制血管平滑肌细胞增殖及表型转化的作用,可用于防治动脉粥样硬化和再狭窄。     

甲基莲心碱对2型糖尿病模型大鼠作用的代谢组学研究

目的研究甲基莲心碱对2型糖尿病模型大鼠尿液的代谢产物的影响。方法高脂高糖饲料喂养联合腹腔注射链尿佐菌素造2型糖尿病大鼠模型,糖尿病造模成功后腹腔注射甲基莲心碱20 mg.kg-1.d-1,4周后测大鼠空腹血糖。收集大鼠24 h尿液,样品经处理后进行UPLC/QTOF-MS分析。结果甲基莲心碱处理组大鼠空腹血糖较糖尿病模型组降低(P<0.05)。甲基莲心碱处理糖尿病大鼠后有4种代谢物的含量发生了明显变化,其中二羟延胡索酸(di-hydroxyfumaric acid)下降,前列腺素I2(prostaglandin I2,PGI2)、脂氧素A4(lipoxin A4,LXA4)、脂氧素B4(lipoxinB4,LXB4)升高。结论甲基莲心碱可降低糖尿病大鼠的血糖,改变糖尿病大鼠尿液的代谢产物,其机制可能与其抗氧化应激、抗炎等作用有关。     

Kinetic analysis of drug disposition and biological response

This review deals with pharmacokinetic/pharmacodynamic analysis of drugs. For the analysis of antipyretics, it was assumed that: (1) The rat body is divided into two compartments, core and skin. (2) Metabolic heat (M) is generated in the core compartment. (3) Heat loss by vaporization (V) is mainly originated from a respiratory effect and occurs in the core compartment. (4) At the skin compartment, heat is gained from the core compartment by conduction (K) and is transferred to the ambient air by radiation and convection. (5) Central nervous system commands efferent signals for M, K and V to change their values according to changes in afferent signals from core and skin temperatures. (6) The effect of antipyretics is shown as afferent signals to the controller. For loop diuretics, it was assumed that: (1) The diuretic rate can be correlated with the urinary excretion rate of diuretics. (2) If there is no intervention in a body fluid regulation system, the relationship between the diuretic rate and the corresponding urinary excretion rate can be described by a Hill equation. (3) Intensity of the body fluid regulation is also described by the Hill equation, in which the intensity is correlated with cumulative amount of drugs excreted in the urine. For neuromuscular blockade, assumptions were: (1) There exists an acetylcholine (ACh) compartment at a motor nerve terminal. (2) ACh in the compartment is eliminated by a first-order rate process. (3) All of the ACh in the compartment is released by one electrical stimulus. (4) The compartment is replenished by two kinds of ACh mobilization. One is a slow mobilization with a constant rate and the other is a momentary mobilization which takes place just after the release of ACh. (5) The released ACh is metabolized immediately after binding to receptors and causing a twitch response. For centrally acting drugs, the quantitative electroencephalographic (EEG) method was used as a surrogate measure of a pharmacological response. Signals from two electrodes fitted on the skull of rats were continuously measured, recorded and subjected to off-line analysis. Total amplitude from aperiodic analysis was taken as an EEG parameter.     

Kinetic model to predict the absorption of nasally applied drugs from in vitro transcellular permeability of drugs

The purpose of this study is to propose a kinetic model to predict the absorption of nasally applied drugs from their permeability to the Caco-2 monolayer (P(Caco-2)). Since a drug applied to the nose in an in vivo physiologic condition is translocated to the gastrointestinal (GI) tract by coordinated beats of cilia (mucociliary clearance, MC), the drug undergoes absorption both from the nasal cavity and from the GI tract. The detailed MC of the rat was examined, using inulin as a marker of the applied solution. Inulin disappeared monoexponentially from the nasal cavity, indicating that the MC can be assumed to follow first-order kinetics. From the disappearance of inulin, the first order rate constant for MC (k(MC)) was calculated as 0.0145 min(-1). In the proposed kinetic model, the fractional absorption of the drug following nasal application is predicted as the sum of F(NC) (fractional absorption from the nasal cavity) and F(GI) (fractional absorption from the GI tract), both of which are estimated indirectly from P(Caco-2). F(NC) is calculated according to the equation, k(a)/(k(a)+k(MC)), where k(a) is the absorption rate constant. Nasal drug absorption is assumed to follow first order kinetics. The k(a) of four drugs was initially calculated from k(MC) and their F(NC); thereafter, the linear relationship between k(a) and P(Caco-2), from which k(a) is predicted, was determined. F(GI) is calculated as F(p.o.)(1-F(NC)), where F(p.o.) is fractional absorption after oral administration. F(p.o.) was predicted from the previously determined sigmoid curve between F(p.o.) and P(Caco-2). The proposed kinetic model is the first estimation system for nasal drug absorption based on drug disposition after nasal application and is useful for the development of nasal dosage forms.     

Pharmacodynamic system analysis of the biophase level predictor and the transduction function.

This work deals with the pharmacodynamic problem of relating a drug effect E(t) to an observable pharmacokinetic (PK) predictor variable r(t), which may be a venous and/or arterial drug level, some other PK variable, or a drug infusion scheme. It is proposed that the relationship between E(t) and r(t) may, in many cases, be appropriately modeled as E(t) = N(F(r(t))) [for practical analysis reasons, F(r(t)) is denoted the biophase level, cb(t), the operator F() is accordingly denoted the biophase level predictor (BLP), and N() is denoted the transduction function (TF)]. This work proposes a method for determining the two fundamental components, BLP and TF, that define the E(t)-r(t) relationship. The BLP is determined by a hysteresis minimization (HM) technique with the following features: (1) the method considers errors in both HM variables; (2) the method is suitable for dealing with the important case in which the predictor variable is a drug infusion scheme; (3) the approach is noncompartmental in contrast to the effect-compartment approaches and it does not require a specific structured modeling of the cb(t)-r(t) relationship when dealing with drugs with linear PKs in a general operational sense; and (4) the method makes use of a dimensionless transformation of the hysteresis variable that eliminates numerical scaling problems so that a complex penalty function optimization approach can be avoided. The TF is determined by a cross validation procedure in conjunction with the BLP determined by HM. The method is demonstrated using pharmacodynamic data for several drugs, considering both concentration-based and drug input-based r(t) values. The significance of the information obtained from the determined BLP and TF is discussed, including the concepts of equilibration dynamics and overloading. The limitations and potential problems of the methodology are discussed.     

Kinetics of uptake and intracellular binding of Cyclosporine A in RAJI cells, in vitro

Uptake characteristics of Cyclosporine A (CsA), an immunosuppressive agent widely used in organ transplantation, have been evaluated in RAJI cells, a human Burkitt lymphoma cell line which (i) does not bear T-cell markers, (ii) is insensitive to CsA after a 1 hr exposure to concentrations up to 50 micrograms/ml, and (iii) does not metabolize CsA. CsA is rapidly accumulated inside the cells until a near steady-state is achieved (within 1-3 min). This uptake is characterized by two components: one linear process saturable at low drug concentrations (lower than 1 microgram/ml) and another not saturable component even at high drug concentrations (up to 50 micrograms/ml). Uptake of CsA is temperature-dependent and unaffected by the presence of CsD, a structural CsA analog (50 micrograms/ml CsD) or sodium azide (10 mM) in the extracellular compartment. Intracellular accumulation of CsA is associated with the rapid appearance of a cytosolic drug-protein complex, which is responsible at least in part, for the large amount of total drug accumulated inside the cells. Chromatographic analysis of this (3H)CsA-macromolecule complex on a Bio-Gel P-60 exclusion column demonstrates that the molecular weight of this protein(s), likely cyclophilin, is around 15,000-20,000 daltons. Using Lineweaver-Burk analysis of binding equilibrium data, the dissociation constant of CsA for this binding site was approximately 2.2 microM. these studies, which demonstrate that CsA (i) is rapidly accumulated inside the cells as free drug but is also specifically bound to an intracellular macromolecule, and (ii) is selectively retained in the intracellular compartment after the extracellular drug is removed, could explain the intense distribution of CsA in the organs and the slow disappearance of CsA from plasma after CsA therapy in humans.     

Influence of light and heat on the stability of rotundine sulfate injection.

The influence of both light and heat on the stability of rotundine sulfate injection was studied. Results show that in experiments with either isothermal heating or exposure to light at high temperatures, the drug coloration rate obeys zero-order kinetics. The total rate constant, k(total), caused by both light and heat can be divided into two parts: k(total)=k(dark)+k(light), where k(dark) and k(light) are the rate constants caused by heat and light, respectively. The k(light) can be expressed as k(light)=A(light)exp(-E(a,light)/RT)E, where E is the illuminance of light, A(light) is an experimental constant related to light sources, and E(a,light) is an experiment constant. Because the form of k(light) is similar to the Arrhenius equation, it is suggested that E(a,light) might be the observed activation energy of the rate-determining step of the subsequent processes of the photochemical reaction. This viewpoint is supported by the fact that E(a,light) is independent of light sources.     

Bicalutamide: clinical pharmacokinetics and metabolism

Bicalutamide is a nonsteroidal pure antiandrogen given at a dosage of 150 mg once daily as monotherapy for the treatment of early (localised or locally advanced) nonmetastatic prostate cancer. It is used at a dosage of 50 mg once daily in combination with a luteinising hormone-releasing hormone analogue or surgical castration for the treatment of advanced prostate cancer. Bicalutamide is a racemate and its antiandrogenic activity resides almost exclusively in the (R)-enantiomer, with little, if any, activity in the (S)-enantiomer. (R)-Bicalutamide is slowly and saturably absorbed, but absorption is unaffected by food. It has a long plasma elimination half-life (1 week) and accumulates about 10-fold in plasma during daily administration. (S)-Bicalutamide is much more rapidly absorbed and cleared from plasma; steady-state concentrations (Css) of (R)-bicalutamide are 100-fold higher than those of (S)-bicalutamide. Css increases linearly with doses up to 50 mg, but nonlinearly at higher doses, reaching a plateau above 300 mg. Css is higher in Japanese than in Caucasians, but no relationship with degree of renal impairment, bodyweight or age exists. Although mild-to-moderate hepatic impairment does not affect pharmacokinetics, there is evidence for slower elimination of (R)-bicalutamide in subjects with severe hepatic impairment. Bicalutamide metabolites are excreted almost equally in urine and faeces with little or no unchanged drug excreted in urine; conversely, unchanged drug predominates in plasma. Bicalutamide in faeces is thought to arise from hydrolysis of bicalutamide glucuronide and from unabsorbed drug. Bicalutamide appears to be cleared almost exclusively by metabolism; this is largely mediated by cytochrome P450 (CYP) for (R)-bicalutamide, but glucuronidation is the predominant metabolic route for (S)-bicalutamide. (S)-Bicalutamide is metabolised in vitro by CYP3A4, and it is probable that this isoenzyme is also responsible for the metabolism of (R)-bicalutamide. In vitro data suggest that (R)-bicalutamide has the potential to inhibit CYP3A4 and, to a lesser extent, CYP2C9, 2C19 and 2D6. However, using midazolam as a specific CYP3A4 marker, no clinically relevant inhibition is observed in vivo with bicalutamide 150mg. Although bicalutamide is a CYP inducer in laboratory animals, dosages < or = 150 mg/day have shown no evidence of enzyme induction in humans. Daily administration of bicalutamide increases circulating levels of gonadotrophins and sex hormones; although testosterone increases by up to 80%, concentrations in most patients remain within the normal range. Bicalutamide produces a dose-related decrease in prostate-specific antigen (PSA) at dosages < or = 150 mg/day. However, little relationship is observed between median PSA reduction and (R)-bicalutamide Css.     

Schiff bis bases: analytical reagents. II. Spectrophotometric determination of manganese from pharmaceutical forms

By condensing ethyl-o-hydroxybenzene with ethylene diamine, and 1-ethyl-salicylidene bis ethylene diamine, a Salen-type Schiff bis base is obtained. These Schiff bis bases present a good capacity of complexing the Mn(II) ions, resulting brown complexes. In this paper, the results of a study concerning the use of the Schiff bis base as reagent in spectrophotometric determination of the Mn(II) is presented. The above mentioned Schiff bis base forms a brown complex with Mn(II) cation, with maximum absorbance at 460 nm, and molar absorbtivity (epsilon)=9.8 x 10(4). The complex with Mn(II) presents a maximum stability at pH 6.0. The combination ratio was established by isomolar series method, and it is 1:2 (metal:ligand). The calculated apparent stability constant is beta(n)=2.943 x 10(-5). The absorbance is proportional to Mn(II) concentration in the range of 10-70 microg ml(-1). In this range, the Lambert-Beer law is respected, the linearity coefficient being 0.9989, S.D.=0.83, R.S.D.=0.88 (n=7). In these conditions, the complexation reaction of Mn(II) is interfered by other cations, Fe(II); Fe(III); Ni(II). The results obtained for spectrophotometric determination of Mn(II) using this Schiff base as reagent were successfully applied to pharmaceutical products containing Mn(II) cation.     

Pegylated interferon with ribavirin therapy for chronic infection with the hepatitis C virus

Chronic infection with the hepatitis C virus is common. In the past, therapy involved a combination of thrice-weekly interferon (IFN) injections combined with oral ribavirin. This therapy was expensive, poorly tolerated and poorly effective, only curing approximately 40% of treated patients. Long-acting IFNs have recently been developed by linking IFN to polyethylene glycol and these 'pegylated' IFNs are now the standard of care for patients with chronic hepatitis C (CHC). Two pegylated (PEG) IFNs are available; 40 kDa PEG-IFNalpha(2a) (Pegasys, Hoffmann-La Roche) and the 12 kDa PEG-IFN-alpha(2b) (Peg-Intron, Schering-Plough). They have different physicochemical, pharmacokinetic and pharmacodynamic properties. The 40 kDa PEG-IFN-alpha(2a) is dispensed as a solution and used at a fixed dose whereas the 12 kDa PEG-IFN-alpha(2b) is a dry powder, which is reconstituted prior to administration, and the dose is dependent upon body weight. Both PEG-IFNs are given by a once-weekly injection and as monotherapy, they are more effective than standard IFN-alpha. The 40 kDa PEGIFN-alpha(2a) cures 36 - 39% of patients and the 12 kDa pegylated-IFN-alpha(2b) cures 23 - 25%. When combined with ribavirin, the two PEG-IFNs have acceptable safety profiles and cure > 50% of treated patients (56 and 54% for the 40 kDa PEG-IFN-alpha(2a) and 12 kDa PEG-IFN-alpha(2b), respectively). For the 40 kDa PEG-IFN-alpha(2a) it is possible to predict the outcome of therapy after 12 weeks of treatment. The new PEG-IFNs are a significant advance in the therapy of CHC infection. Their ease of administration, coupled with their improved efficacy, is likely to lead to an increase in the proportion of infected patients who wish to receive treatment.     

ACE2: a new target for cardiovascular disease therapeutics

The discovery of angiotensin-converting enzyme 2 (ACE2) in 2000 is an important event in the renin-angiotensin system (RAS) story. This enzyme, an homolog of ACE, hydrolyzes angiotensin (Ang) I to produce Ang-(1-9), which is subsequently converted into Ang-(1-7) by a neutral endopeptidase and ACE. ACE2 releases Ang-(1-7) more efficiently than its catalysis of Ang-(1-9) by cleavage of Pro(7)-Phe(8) bound in Ang II. Thus, the major biologically active product of ACE2 is Ang-(1-7), which is considered to be a beneficial peptide of the RAS cascade in the cardiovascular system. This enzyme has 42% identity with the catalytic domain of ACE, is present in most cardiovascular-relevant tissues, and is an ectoenzyme as ACE. Despite these similarities, ACE2 is distinct from ACE. Since it is a monocarboxypeptidase, it has only 1 catalytic site and is insensitive to ACE inhibitors. As a result, ACE2 is a central enzyme in balancing vasoconstrictor and proliferative actions of Ang II with vasodilatory and antiproliferative effects of Ang-(1-7). In this review, we will summarize the role of ACE2 in the cardiovascular system and discuss the importance of ACE2-Ang-(1-7) axis in the control of normal cardiovascular physiology and ACE2 as a potential target in the development of novel therapeutic agents for cardiovascular diseases.     

Quinolizidine derivatives with antimicrobial activity

Thirty quinolizidinyl derivatives, together with two dialkylaminoalkyl analogues, were tested at concentration up to 160 mg/l for antimicrobial activity against 17 microrganisms, including gram-positive and gram-negative strains, Mycobac, tuberculosis, Trichom, vaginalis, fungi and yeasts. The most common activity found is that against Mycobac, tuberculosis, followed by that against gram-positive strains; several compounds [(I a), (I b), (I c), (II a), (III a), (VIII e), (XIX e), (XXI e)] exhibit a good or a very high level of activity. Concerning the gram-negative bacteria, activity is found only against Escherichia coli and is random and usually slight, as is that against fungi, yeasts and protozoa. Compounds (I a), (III a) and (XXI e) are of interest for their high activity and for their broad spectrum of activity, while compound (X e) is peculiar for its selectivity against Mycobac. tuberculosis.