The pharmacological actions of (m-hydroxyphenethyl)-trimethylammonium (leptodactyline)

Leptodactyline is a naturally occurring quaternary ammonium base, which is found in large amounts in the skin of some South American amphibians of the genus Leptodactylus. It is the first example of a m-hydroxyphenylalkylamine in the living organism. In vertebrates it had powerful nicotinic actions and a marked neuromuscular blocking effect. This was considered, on the basis of experimental evidence, to be of the “depolarizing” type.     

Kinetics of the inhibition of human serum cholinesterase phenotypes with the dimethylcarbamate of (2-hydroxy-5-phenylbenzyl)-trimethylammonium bromide (Ro 02-0683).

The inhibition of the human serum cholinesterase phenotypes, usual (U), atypical (A) and heterozygous (UA), by the dimethylcarbamate of (2-hydroxy-5-phenylbenzyl)-trimethylammonium bromide (Ro 02-0683), was followed with benzoylcholine, acetyl-, butyryl- and propionyl-thiocholine as substrates. The first-order rate constants were calculated from the linear part of the inhibition curves and were independent of the substrate used for measuring the enzyme activity. The second-order rate constants for the U, UA and A phenotypes were 8.3 x 10(6), 6.1 x 10(6) and 0.05 x 10(6) M-1 min-1, respectively. The constant of the enzyme-inhibitor complex for the atypical serum was 7.7 microM, and the rate of carbamylation of the enzyme was 0.386 min-1. The rate of reactivation of carbamylated usual and atypical enzyme was found to be same; the half-time of reactivation was about 3.5 hr. The deviation from the linearity of the inhibition course was explained by spontaneous reactivation of the inhibited enzyme; the theoretical inhibition curves were in good agreement with the experimentally obtained values. The three phenotypes could be distinguished by the rate of inhibition by the dimethylcarbamate, Ro 02-0683, in the progressive phase of inhibition or by the degree of inhibition in the apparent steady-state.     

1,1’-(联苯基-4,4’)-二[3-(二甲氨基)-1-丙酮]对阿尔茨海默病小鼠的影响

目的 研究1,1’-(联苯基-4,4’)-二[3-(二甲氨基)-1-丙酮](BDBDP)对东莨菪碱致小鼠阿尔茨海默病(AD)的作用及其机制.方法 将50只ICR小鼠随机分为正常组、模型组及BDBDP低、中、高剂量组.连续ip给药18d,第13天ip东莨菪碱造模,并采用Morris水迷宫及Y迷宫进行行为学测试;测定小鼠脑组织中乙酰胆碱酯酶(AChE)、胆碱乙酰转移酶(ChAT)、超氧化物歧化酶(SOD)的活性.结果 BDBDP能缩短水迷宫实验中小鼠的逃避潜伏期,并提高目标象的限滞留时间;可提高Y迷宫试验中小鼠的自发交替率,且不影响小鼠的活动能力;还能降低小鼠脑组织中AChE的活性,提高ChAT和SOD的活性.结论 BDBDP对东莨菪碱所致小鼠AD模型有明显改善作用,其机制可能与其作用于胆碱能系统及其抗氧化作用有关.     

Effects of (+)-1,2-bis(3,5-dioxopiperazin-1-yl)propane (ADR-529) on iron-catalyzed lipid peroxidation

ADR-529 [(+)-1,2-bis(3,5-dioxopiperazin-1-yl)propane], a nonpolar, cyclic analogue of EDTA, protects against anthracycline cardiotoxicity in vivo. The protective mechanism presumably involves chelation of iron by a hydrolysis product of ADR-529, thus preventing the formation of reactive iron/oxygen species which can damage membrane lipids. We investigated the effects of ADR-529 and its hydrolysis products (the tetraacid and the diacid diamide) on NADPH- and ADP-Fe(3+)-dependent lipid peroxidation of rat liver microsomes and liposomes in the presence of cytochrome P-450 reductase. Hydrolyzed ADR-529 products caused inhibition of lipid peroxidation when in excess of the iron concentration. However, no inhibition of lipid peroxidation was detected by similar concentrations of nonhydrolyzed ADR-529. Microsomes did not affect the inhibition of lipid peroxidation, suggesting that rat liver microsomes do not hydrolyze ADR-529. Similarly, the diacid diamide hydrolysis product of ADR-529 inhibited ferritin- and adriamycin-iron-dependent liposomal lipid peroxidation in a concentration-dependent manner. No correlation between partially reduced oxygen species (O2.- and .OH; as measured by electron spin resonance) and lipid peroxidation (as assayed by malondialdehyde formation) was observed, suggesting that liposomal lipid peroxidation was strictly an iron-dependent phenomenon. These results suggest that inhibition of lipid peroxidation by iron chelation may be related to the protective effects of ADR-529 on in vivo anthracycline toxicity.     

Relationship between changes in seromucoid concentrations and the rate of oxidation or acetylation of several substrates

This study was carried out to assess the relationship between turpentine-induced elevation of seromucoids and drug metabolism. Six groups of rats were used; one of them received 1 ml of turpentine sc, another received 1 ml of turpentine by gavage (po), and a third group received, ip, 80 mg/kg of phenobarbital daily for 3 days. Three control groups received saline instead of turpentine. Forty-eight hr later, the serum seromucoids were assayed and the rates of N-demethylation of aminopyrine, O-dealkylation of 7-ethoxycoumarin, and hydroxylation of aniline and total cytochrome were determined in liver microsomes. When turpentine was administered sc, seromucoids increased from 3.15 +/- 0.18 to 16.13 +/- 0.84 g/dl (mean +/- SE) (p less than 0.01), but the rates of N-demethylation (p less than 0.01), of O-dealkylation (p less than 0.01) and of hydroxylation (p less than 0.05) were all decreased. In the rats receiving turpentine po, seromucoids remained unchanged, but the rates of N-demethylation and O-dealkylation as well as the concentration of total cytochrome increased (p less than 0.01). Phenobarbital enhanced significantly the rates of N-demethylation, O-dealkylation, and hydroxylation and the total concentration of cytochrome, without modifying the concentration of seromucoids. In another set of experiments we assessed whether turpentine-induced inflammation would affect the in vivo rate of acetylation of sulfamethazine; the results show that inflammation does not affect the rate of acetylation, despite an important increase in seromucoids. It is concluded that, under the present experimental conditions, there is no direct relationship between changes in seromucoids and the rate of drug metabolism.     

Effects of AVS (1,2-bis(nicotinamido)propane) on platelet function and vascular endothelium

The effects of 1,2-bis(nicotinamido)propane (AVS) on platelet function and vascular endothelium were investigated using various experimental thrombosis and vascular endothelial injury models. Neither in vitro platelet aggregation induced by ADP, collagen or arachidonate nor ex vivo platelet aggregation by ADP or collagen could be antagonized by AVS. On the other hand, AVS prevented mice, rats and rabbits from death induced by acute cerebral or pulmonary thromboembolism following the injection of arachidonate or collagen. These activities were as potent as those of acetylsalicylic acid. The disrupting actions of citrate and/or lipidperoxide (13-hydroperoxy linoleic acid) on endothelium were well inhibited by the pretreatment of AVS. AVS did not inhibit cyclooxygenase, increased prostacyclin (PGI2)/thromboxane A2 (TXA2) ratio in the coupled system of platelets and aortic microsomes. In conclusion, AVS inhibited thrombus formation in vivo while it was ineffective in vitro platelet alone system, which may result from the actions of this agent on both platelets and vascular endothelium. The above-mentioned results clearly show that AVS may be a new potent anti-vascular damaging agent with both endothelium stabilizing and PGI2 enhancing activities.     

Effects of the schistosomicide 1,7-bis(p-aminophenoxy)heptane (153C51) on lysosomes and membrane stability

The schistosomicide 1,7-bis(p-aminophenoxy)heptane (153C51) stabilised mouse erythrocytes and rat liver lysosomes against osmotic lysis. Chloroquine was less potent in either system in terms of the maximum stabilisation achieved or the concentration needed to produce the maximum effect. Two lysosomal enzymes, acid phosphatase and β-acetylglucosaminidase, were partially inhibited by 153C51. Binding of [³H]-153C51 by rat liver lysosomes was directly proportional to the drug concentration. The results are discussed in relation to the amphiphilic, cationic properties of the drug molecule and the effect of 153C51 on lysosomes in the tegument of the blood fluke Schistosoma mansoni.     

Synthesis,Antidepressant Activity,and Toxicity of the Erythro/Threo Racemates and Optical Isomers of 2-(4-benzylpiperazin-1-yl)-1-(5-chloro-6-methoxynaphthalen-2-yl)hexan-1-ol

The erythro/threo racemates and their four optical isomers of 2-(4-benzylpiperazin-1-yl)-1-(5-chloro-6-methoxynaphthalen-2-yl)hexan-1-ol were synthesized and evaluated for their antidepressant activity, toxicity, and pharmacokinetics as novel triple multiple reuptake inhibitors of monoamine transmitters. The racemates and optical isomers were synthesized, respectively, through two different routes. Pharmacological data indicate that the erythro racemate ( SIPI5357 ) that has better inhibitory activity and lower toxicity than the other racemate and optical isomers is worthy of further evaluation.     

Effects of choline 2:6-xylyl ether bromide upon the suprarenal medulla of the rat

The administration of choline 2:6-xylyl ether bromide (TM 10) daily to rats for two weeks depletes the suprarenals of about one-half their normal content of adrenaline and noradrenaline. This depletion has been demonstrated histologically and by colorimetric and biological estimation of the amines present in extracts of the glands. Treatment with TM 10 causes similar histological signs of depletion in autografts of adrenal chromaffin tissue in the rat iris. Restoration of catechol amines in rat suprarenals, previously depleted by TM 10, occurs slowly and appears to be complete 14 days after withdrawing the drug. These results, considered in conjunction with the estimated rate of turnover of catechol amines in the rat suprarenal, lend support to the view that TM 10 may interfere with the biosynthesis of these amines.     

Comparison of (S)-mephenytoin and proguanil oxidation in vitro: contribution of several CYP isoforms

AIMS: To compare the oxidative metabolism of (S)-mephenytoin and proguanil in vitro and to determine the involvement of various cytochrome P450 isoforms. METHODS: The kinetics of the formation of 4'-hydroxymephenytoin and cycloguanil in human liver microsomes from 10 liver samples were determined, and inhibition of formation was studied using specific chemical inhibitors and monoclonal antibodies directed towards specific CYP450 isoforms. Expressed CYP450 enzymes were used to characterize further CYP isoform contribution in vitro. Livers were genotyped for CYP2C19 using PCR amplification of genomic DNA followed by restriction endonuclease digestion. RESULTS: All livers were wildtype with respect to CYP2C19, except HLS#5 whose genotype was CYP2C19*1/CYP2C19*2. The Km, Vmax and CLint values for the formation of 4'-hydroxymephenytoin from (S)-mephenytoin and the formation of cycloguanil from proguanil ranged from 50.8 to 51.6 and 43-380 microm, 1.0-13.9 and 0.5-2.5 nmol mg-1 h-1, and 20.2-273.8 and 2.7-38.9 microl h-1 mg-1, respectively. There was a significant association between the Vmax values of cycloguanil and 4'-hydroxymephenytoin formation (rs=0.95, P=0.0004). Cycloguanil formation was inhibited significantly by omeprazole (CYP2C19/3A), troleandomycin (CYP3A), diethyldithiocarbamate (CYP2E1/3A), furafylline (CYP1A2), and (S)-mephenytoin. 4'-Hydroxymephenytoin formation was inhibited significantly by omeprazole, diethyldithiocarbamate, proguanil, furafylline, diazepam, troleandomycin, and sulphaphenazole (CYP2C9). Human CYP2E1 and CYP3A4 monoclonal antibodies did not inhibit the formation of cycloguanil or 4'-hydroxymephenytoin, and cycloguanil was formed by expressed CYP3A4 and CYP2C19 supersomes. However, only expressed CYP2C19 and CYP2C19 supersomes formed 4'-hydroxymephenytoin. CONCLUSIONS: The oxidative metabolism of (S)-mephenytoin and proguanil in vitro is catalysed by CYPs 2C19 and 1A2, with the significant association between Vmax values suggesting that the predominant enzymes involved in both reactions are similar. However the degree of selectively of both drugs for CYP isoforms needs further investigation, particularly the involvement of CYP3A4 in the metabolism of proguanil. We assert that proguanil may not be a suitable alternative to (S)-mephenytoin as a probe drug for the CYP2C19 genetic polymorphism.     

Effects of Doxorubicin (Adriamycin) and [(+)-1,2-bis(3,5-dioxopiperazinyl-1-yl)]propane (ICRF-187) on skeletal muscle protease activities

Adverse effects of doxorubicin (adriamycin) have been reported to be due to iron-catalyzed free radical formation, which can be prevented with the cytoprotective chelating agent [(+)-1,2-bis(3,5-dioxopiperazinyl-1-yl)]propane (dexrazoxane; ICRF-187). Affected tissues include the heart, gastrointestinal tract, and kidney. However, there is very little information on the effects of adriamycin on skeletal muscle, despite the fact that there is direct and indirect evidence to show that both adriamycin and ICRF-187 are myotoxic. To investigate the mechanisms of cytotoxicity of these agents in skeletal muscle, we have conducted a systematic investigation of the activities of the major lysosomal (dipeptidyl aminopeptidase I and II and cathepsins B, D, H, and L) and cytoplasmic (alanyl-, arginyl-, and leucyl aminopeptidase, dipeptidyl aminopeptidase IV, tripeptidyl aminopeptidase, and proline endopeptidase) muscle proteases. These enzymes play an important role in normal cellular function and represent potential targets for toxic and protective agents. Male Wistar rats (approx. 0.2 kg) were subjected to a pretreatment phase of 30 min followed by a treatment stage of either 2.5 or 24 h. The pretreatment involved injection of a single bolus of either saline (0.15 mol/l NaCl; 5 ml/kg ip) or ICRF-187 (100 mg/kg; 5 ml/kg ip). After 30 min, rats were injected again with a single bolus of either adriamycin (5 mg/kg; 10 ml/kg ip) or saline (0.15 mol/l NaCl; 10 ml/kg ip) in the treatment phase. At either 2.5 or 24 h after the last adriamycin or saline injection, rats were killed for subsequent dissection of the gastrocnemius muscle for analysis. In the 2.5-h study, there were significant reductions in cathepsin D activities of adriamycin-treated rats compared to saline injected control (p = 0.02). In both 2.5- and 24-h studies there were also significant differences (p = 0.05) in cathepsin H activities between rats treated with adriamycin and ICRF-187, although these differences were not significant when data were compared with corresponding saline-injected rats. There were no other overt effects for any of the other proteases at either 2.5 or 24 h. We conclude that both adriamycin and ICRF-187 have very little effect on the activities of muscle proteases and that altered proteolysis is not involved in the reported pathological reactions induced by these agents.     

3,3-二(二苄氧膦酰基)丙酸和3,3-二(二苄氧膦酰基)丙醇的合成

目的 合成3,3-二(二苄氧膦酰基)丙酸(5)和3,3-二(二苄氧膦酰基)丙醇(6)。方法以亚甲基偕二膦酸四乙酯(1)为原料经水解、氯膦酰化、酯化、缩合得3,3-二(二苄氧膦酰基)丙酸(5),随后选择性硼氢化还原得3,3-二(二苄氧膦酰基)丙醇(6)。结果化合物(5)、(6)的结构经IR、^1HNMR和质谱确证。结论所用方法合成3,3-二(二苄氧膦酰基)丙酸(5)和3,3-二(二苄氧膦酰基)丙醇(6)较理想。     

1-(对羟苄基)-N-甲基-6-甲氧基-7-羟基异喹啉对α肾上腺素受体的作用

在大鼠输精管上,BMIQ 10μmol/L和YHB 1μmol/L都能使CLN的量效曲线平行右移,最大反应不变,表明二者均能竞争性地阻断突触前α_2受体,其pA_2值分别为6.69和7.8.大鼠肛尾肌实验表明,BMIQ亦有竞争性拮抗突触后α_1受体作用,pA_2值为5.14。其α_2/α_1阻断作用之比率为35.5,说明BMIQ对α_2受体的选择性大于α_1受体.BMIQ和YHB在毁脊髓大鼠标本上,均能使B—HT920升高舒张血压的量效曲线平行右移,最大反应不变.二者的剂量比率分别为2.7和14.8,且BMIQ抗突触后膜α_2受体作用仅为YHB的1/5.5。     

硝苯啶对血浆血栓烷B_2与6-酮-前列腺素F_(1α)平衡作用的影响

22例冠心病患者(男18例,女4例;年龄65±5yr)用硝苯啶5mg,tid,po,4wk为一个疗程;服药前、后分别作血浆血栓烷B_2(TXB_2)、6-酮-前列腺素F_(1α)(6-K-PGF_(1α))和血清脂质测定。发现平均TXB_2浓度明显降低,6-K-PGF_(1α)浓度改变不明显,从而使6-K-PGF_(1α)/TXB_2比值明显增加(P<0.01);同时发现HDL-ch浓度升高,LDL-ch浓度下降,证明硝苯啶对冠心病防治有益。     

Potentiation of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU)-induced cytotoxicity in 9L cells by pretreatment with 6-thioguanine

9L Rat brain tumor cells were treated with 0.2 microM 6-thioguanine for 48 hr, which produced a 40% cell kill, a small (15%) inhibition of cell growth, and an accumulation of cells in S-phase. Maximum incorporation of [14C]6-thioguanine into cellular DNA occurred after 24 hr of incubation; 70% of the label was incorporated into DNA as 6-thio-2'-deoxyguanosine. Pretreatment of 9L cells for 48 hr with 0.2 microM 6-thioguanine potentiated the cytotoxicity of 1,3-bis (2-chloroethyl)-1-nitrosourea (BCNU) by 50% with a dose enhancement ratio of 1.5, and caused a 30% increase in the number of BCNU-induced sister chromatid exchanges (SCEs) and a 50% increase in DNA crosslinks formed, compared to treatment with BCNU alone. Used as a single agent, 6-thioguanine induced a significant number of SCEs. Results suggest that these effects may be related to the increased formation of DNA crosslinks, possibly as the result of the formation of S6-(2-chloroethyl)-6-thioguanine in cellular DNA.