鸟嘌呤核苷-3′,5′-环磷酸衍生物的合成及生物活性研究

本文报道用三价磷试剂与保护的鸟嘌呤核苷反应,经碘氧化生成鸟嘌呤核苷-3′,5′-环磷酸酯和磷酰胺,并对它们的生物活性做了初步研究,N²-二甲胺基甲烯基-2′-叔丁基二甲基硅基鸟嘌呤核苷-3′,5′-环磷酸酯和磷酰胺对小鼠肝癌腹水细胞的DNA和RNA合成有一定的抑制作用。N²-二甲胺基甲烯基鸟嘌呤核苷-3′,5′’-环磷酸丁酯的两个磷原子构型不同的异构体可激活腺苷酸环化酶,使大鼠成骨肉瘸细胞株ROS 17/2.8的cAMP水平增高。     

阿糖腺苷2′,5′-环磷酸酯和阿糖腺苷5′-亚磷酸酯的合成

为提高抗病毒药阿糖腺苷(Ara-A)的水溶性,合成了阿糖腺甘2′,5′-环磷酸酯,阿糖腺苷5′亚磷酸酯以及相应的酰基衍生物。抗病毒筛选结果表明,阿糖腺苷2′,5′-环磷酸酯在1μg/ml 浓度时对Ⅰ型单纯疱疹病毒有明显抑制作用。     

腺嘌呤核苷3′,5′-环甲基膦酸与硫代环甲基膦酸的合成

腺嘌呤核苷3′,5′-环磷酸(cAMP)在细胞增殖和分化过程中起重要作用,其磷酸部分的修饰物可能作为cAMP在体内的模拟物、拮抗物或贮存形式而发挥作用,还有的表现出抗癌作用。为进一步研究cAMP的磷酸部分修饰与生物活性间的关系,研究cAMP中磷原子的立体化学对生物活性可能的影响,我们设计了腺嘌呤核苷3′,5′-环甲基膦酸类     

N4-烷基-5-甲基-2′-脱氧胞苷的合成

3′,5′-O-二苯甲酰胸苷在三氯氧磷存在的条件下与1,2,4-三唑缩合可得到1-(3′,5′-O-二苯甲酰-β-D-呋喃核糖)- 4-(1,2,4-三唑-1-基)-5-甲基-嘧啶-2-(1H)-酮,再用不同的胺取代核苷C4上的三唑基团可制备一系列全新的N4-烷基取代的5-甲基胞苷.方法简便 ,收率高.     

二种双脱氧脱氢核苷的合成研究

目的:对双脱氧脱氢核苷的合成进行了研究。方法:以2′-脱氧核苷为原料,先用甲磺酰氯(MsCl)将3′5′-位羟基保护,然后在NaOH水溶液中形成3′5′-0-环状物,再与叔丁醇钾(t-BuOK)作用生成2′,3′-二脱氧-2′,3′-二脱氢核苷化合物。结果:合成了2′,3′-二脱氧-2′,3′-二脱氢尿苷(总收率34.4%)及2′,3′-二脱氧2′3′-二脱氢胸苷(总收率52.3%)。结论:产品经紫外可见光谱,质谱及核磁共振谱表征,结构确认,说明用此法合成嘧啶类双脱氧脱氢核苷是可行的。     

抗癌药5-氟尿嘧啶-2′-脱氧核糖核苷合成路线改进

本文介绍了由5′-尿嘧啶核糖核苷酸二钠盐,经化学法脱磷酸,得尿嘧啶核糖核苷,在无水乙腈中与丙酰溴反应,得3′,5′-二丙酰-2′-脱氧-2′-溴代尿嘧啶核糖核苷,催化氢化脱溴,得3′,5′-O-二丙酰基-2′-脱氧尿嘧啶核糖核苷,用氟氮混合气氟化,甲醇-氨水脱保护基,制得5-氟尿嘧啶-2′-脱氧核糖核苷的方法。起始原料为味精厂综合利用产品。     

5′-脱氧-5-氟胞苷类衍生物的合成及其抗肿瘤活性

目的设计并合成具有抗肿瘤活性的5′-脱氧-5-氟胞苷类衍生物。方法2′,3′-O-二乙酰-5′-脱氧-5-氟胞苷在三氯氧磷存在下与1,2,4-三唑缩合得到1-(2′,3′-O-二乙酰-5′-脱氧-β-D-呋喃核糖)-4-(1,2,4-三唑-1-基)-5-氟嘧啶-2-(1H)-酮(3),后者用不同的亲核基团取代核苷C-4位上的三唑基团,制备一系列含有烷基胺、烷氧基和脒基的5′-脱氧-5-氟胞苷类衍生物。结果合成了15个未见报道的新化合物,化合物的结构经1H-NMR、FAB-MS及元素分析确证。结论抗肿瘤活性测试表明,其中某些化合物的活性与对照药物卡培他滨相当,对肺癌、结肠癌、乳腺癌和肝癌细胞显示出较好的抑制活性。     

N6-苯甲酰基-2'-叔丁基二甲基硅氧基腺苷-3'-H-膦酸的合成工艺研究

目的 研究N~6-苯甲酰基-2′-叔丁基二甲基硅氧基腺苷-3′-H-膦酸的合成工艺。方法 以腺苷为起始原料,先对腺苷的嘌呤氨基进行苯甲酰基保护,再分别向腺苷的5′位和2′位引入二甲氧基三苯甲基(DMT)和叔丁基二甲基硅基(TBDMS)保护基,制备得到关键中间体N~6-苯甲酰基-5′-二甲氧基三苯甲氧基-2′-叔丁基二甲基硅氧基腺苷(3)。中间体3与磷试剂2-氯-4H-1,3,2-苯并二氧磷杂环己烷-4-酮反应引入膦酸基团,最后使用二氯乙酸脱除DMT保护基得到目标产物。结果 经过5步反应得到了目标化合物N~6-苯甲酰基-2′-叔丁基二甲基硅氧基腺苷-3′-H-膦酸,并利用~1H-NMR、~(31)P-NMR、质谱等方法确证了其结构。本合成工艺的总收率为35.7%,目标化合物的质量分数为98.5%。结论 该合成工艺与原有方法相比步骤短,操作简单,具有良好的应用前景。     

嘧啶和嘌呤核苷类似物的抗病毒活性的靶点

结构稍加修饰的天然核苷类似物在病毒复制过程中是以某些关键酶为专属靶点的.这些修饰包括在嘧啶环5-位的取代,无论是否同时伴有糖环2',3'-双脱氧或2',3'-双脱氢,或以环戊基、环戊烯基取代糖环.嘌呤核苷可通过改变糖环为环戊基或环戊烯基,或糖环为开链所取代,得到抗病毒药.已经试验有明显抗病毒作用的无环核苷类似物,如9-(2-羟乙氧基甲基)鸟嘌呤(无环鸟苷)等.胸苷酸合成酶     

抗肿瘤药物2′-脱氧-5-氟尿苷合成研究

目的:合成抗肿瘤药物2′-脱氧-5-氟尿苷。方法:以5-氟尿嘧啶核苷为原料,经丙酰溴酰化溴代得2′-溴代-3,′5′-O-二丙酰基-5-氟尿嘧啶核苷,然后氢化得产物2′-脱氧-3,′5′-O-二丙酰基-5-氟尿嘧啶核苷,最后经皂化合成2′-脱氧-5-氟尿苷。结果:以5-氟尿嘧啶核苷为起始原料经3步反应合成了2′-脱氧-5-氟尿苷。结论:本合成方法工艺简便,原料易得,条件温和,总收率为72.0%,适于工业制备。     

Inhibition by guanosine cyclic monophosphate (cGMP) analogues of uptake of [(3)H]3',5'-cGMP without stimulation of ATPase activity in human erythrocyte inside-out vesicles.

The cellular extrusion of guanosine 3',5'-cyclic monophosphate (3',5'-cGMP) is a unidirectional ATP-dependent process that is inhibited by probenecid, a non-selective transport inhibitor of organic anions. In the present study, various cGMP analogues were tested for their ability to inhibit 3',5'-cGMP efflux and stimulate the cGMP-selective ATPase in human erythrocytes. The difference in uptake of 1 microM [(3)H]3',5'-cGMP to inside-out vesicles in the presence and absence of 1 mM ATP at 37 degrees was defined as active transport. Two ATP-dependent components were detected for unlabelled 3',5'-cGMP (0.01--100 microM) with respective K(i) of 1.3 +/- 0.2 and 280 +/- 50 microM (mean +/- SEM, N = 3). The high-affinity transport was inhibited by the analogues with a typical pattern: Rp-monophosphorothioate guanosine 3',5'-cyclic monophosphate (Rp-cGMPS) > 3',5'-cGMP > 2'-O-monobutyryl guanosine 3',5'-cyclic monophosphate (O-mb-cGMP) approximately N(2)-monobutyryl guanosine 3',5'-cyclic monophosphate (N-mb-cGMP) > or = N(2),2'-O-dibutyryl guanosine 3',5'-cyclic monophosphate (Db-cGMP) approximately 8'-bromo guanosine 3',5'-cyclic monophosphate (Br-cGMP) approximately Guanosine 2',3'-cyclic monophosphate (2'3'-cGMP) > Sp-monophosphorothioate guanosine 3',5'-cyclic monophosphate (Sp-cGMPS). A concentration-dependent inhibition was found for the low-affinity transport, but no distinct order of potency was identified. Analysis according to Lineweaver--Burk of active [(3)H]3',5'-cGMP transport (0.2--2 microM) gave a K(m) value of 1.5 +/- 0.1 microM (mean +/- SEM, N = 3). The presence of 10 microM cGMP analogues did not change the ordinate intercept, but made the slopes steeper with a typical order: Rp-cGMPS > 3',5'-cGMP > N-mb-cGMP approximately O-mb-cGMP approximately db-cGMP approximately 8-Br-cGMP > 2',3'-cGMP > Sp-cGMPS. Only 3',5'-cGMP and 2',3'-cGMP were able to activate the cGMP-specific ATPase, 640 +/- 200% and 430 +/- 160% (mean +/- SEM, N = 5) above basal levels, respectively. The present data show that the binding is less selective than ATPase activation of the cellular cGMP transport system.     

The preparation of 2'-deoxy-2'-fluoro-1',2'-seconucleosides as potential antiviral agents

The preparation of (R,R)-1,3-dibenzyl-4-fluorobutane-1,2,3-triol (6) from D-isoascorbic acid and subsequent chloromethylation of this chiron made possible the synthesis of a series of 2'-deoxy-2'-fluoro-1',2'-seconucleosides. Among them were the uridine (10), thymidine, (11), 5-iodouridine (14), ribavirin (17), and guanosine (19) analogues. They were evaluated for antiviral activity primarily against RNA viruses and found to be inactive. In addition to the aforementioned acyclonucleosides, the 3',5'-cyclic phosphates of the uridine (22) and thymidine (23) analogues were prepared from their respective 4-nitrophenyl 3',5'-cyclic phosphate triesters. The triesters were also examined for antiviral activity, but like their nucleoside counterparts exhibited only marginal activity.     

Effects of cyclic GMP and analogues on neurogenic transmission in the rat tail artery.

1. The effects of membrane permeable analogues of guanosine 3':5'-cyclic monophosphate (cyclic GMP), and of the NO donor, 3-morpholinosydnonimine-N-ethylcarbamide (SIN-1) were investigated on [3H]-noradrenaline release and neurogenic vasoconstriction in electrical field stimulated rat tail arteries. 2. Two 8-substituted analogues of cyclic GMP (8-bromoguanosine 3':5'-cyclic monophosphate; 8-bromo-cyclic GMP and 8-(4-chlorophenylthio)-guanosine 3':5'-cyclic monophosphate; 8-pCPT-cyclic GMP) concentration-dependently enhanced stimulation-induced [3H]-noradrenaline release. These prejunctional effects were antagonized by the cyclic AMP-dependent protein kinase (PKA) inhibitor N-[2-((3-(4-bromophenyl)-2-propenyl)-amino)-ethyl]-5 isoquinolinesulphonamide dihydrochloride (H-89; 100 nM) but not by the cyclic GMP-dependent protein kinase (PKG) inhibitors, Rp-8-bromoguanosine 3':5'-cyclic monophosphorothioate (Rp-8-bromo-cyclic GMPS; 10 microM) or Rp-8-(4-chlorophenylthio)-guanosine 3':5'-cyclic monophosphorothioate (Rp-8-pCPT-cyclic GMPS; 10 microM). 3. beta-Phenyl-1,N2-ethenoguanosine 3':5'-cyclic monophosphate (PET-cyclic GMP) had no effect on stimulation-induced [3H]-noradrenaline release but concentration-dependently decreased the stimulation-induced vasoconstriction. 4. The two 8-substituted cyclic GMP derivatives, PET-cyclic GMP and SIN-1, both decreased stimulation-induced vasoconstriction. In addition, SIN-1 relaxed rat tail arteries precontracted with phenylephrine (1 microM). The SIN-1 concentration-relaxation curve was shifted in parallel manner to the right by Rp-8-bromo-cyclic GMPS (10 microM) and Rp-8-pCPT-cyclic GMPS (10 microM) with no change in the maximum effect, showing that the relaxation was mediated by a cyclic GMP/PKG-dependent mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)     

Stimulation of muscarinic M2 receptors inhibits atrial natriuretic peptide-mediated relaxation in bovine tracheal smooth muscle

The influence of muscarinic M(2) receptors to modulate the relaxant effects of atrial natriuretic peptide (ANP) and sodium nitroprusside (SNP) was investigated in bovine tracheal smooth muscle. In bovine tracheal smooth muscles contracted with methacholine (0.3 micro M), methoctramine (0.03 micro M), a selective muscarinic M(2) receptor antagonist, augmented the relaxant responses to ANP without affecting the responses to SNP and 8-(4-chlorophenylthio)guanosine 3',5'-cyclic monophosphate. Pertussis toxin (PTX; 200 ng/ml for 18 h) augmented the relaxation and accumulation of guanosine 3',5'-cyclic monophosphate produced by ANP. These results suggest that the stimulation of muscarinic M(2) receptors suppresses ANP-induced activation of particulate guanylyl cyclase via a PTX-sensitive G protein.     

A synthetic study on cyclic phosphate derivatives of seconucleosides as potential antiviral agents (I): Synthesis of 3′,5′-cyclic phosphates of 2′-substituted secouridines and secoribavirins

The synthetic study of 3',5-cyclic phosphates of 2'-substituted 2',3'-secouridines and 2',3'-secoribavirins toward development of new antiviral agents is described. These cyclic phosphates were synthesized from their respective 4-nitrophenyl 3',5'-cyclic phosphate triesters. These triesters were prepared from the corresponding 2'-azido and 2'-bromo 2',3'-seconucleosides.     

Endothelium-dependent and -independent effects of exogenous ATP, adenosine, GTP and guanosine on vascular tone and cyclic nucleotide accumulation of rat mesenteric artery.

1. The effects of exogenous guanosine 5'-triphosphate (GTP) and guanosine on vascular tone and cyclic nucleotide accumulation of noradrenaline-precontracted endothelium-intact and endothelium-denuded rat mesenteric artery rings were compared with the effects of the known purinoceptor agonists adenosine 5'-triphosphate (ATP) and adenosine. 2. GTP (10 microM-1 mM) dose-dependently relaxed endothelium-intact mesenteric artery rings by producing a rapid initial response followed by sustained relaxation resembling the relaxant response to acetylcholine. GTP also slightly relaxed endothelium-denuded artery rings. The acetylcholine- and GTP-induced relaxations of endothelium-intact rings were attenuated by NG-nitro L-arginine methyl ester (L-NAME, 330 microM) which attenuation was reversed with L-arginine (1 mM). 3. Guanosine (10 microM-1 mM) relaxed both endothelium-intact and -denuded artery rings in a dose-dependent manner. The relaxations were more pronounced in endothelium-intact preparations and were only slightly attenuated by L-NAME (330 microM). 4. ATP (1 microM-1 mM) and adenosine (10 microM-1 mM) dose-dependently relaxed endothelium-intact and -denuded artery rings. The responses were more pronounced in endothelium-intact vascular preparations. 5. GTP (100 microM) and guanosine (100 microM) increased guanosine 3':5'-cyclic monophosphate (cyclic GMP) accumulation in both endothelium-intact and -denuded artery rings corresponding to the relaxations observed. The concentrations of adenosine 3':5'-cyclic monophosphate (cyclic AMP) were not affected. 6. ATP (100 microM) increased cyclic GMP concentration of endothelium-intact artery rings. The concentrations of cyclic AMP were not affected by ATP (100 microM) and adenosine (100 microM) in endothelium-intact and -denuded vascular preparations.(ABSTRACT TRUNCATED AT 250 WORDS)     

The role of cyclic nucleotides and related compounds in nerve-mediated vasodilatation in the cat submandibular gland.

1 Intra-arterial administration of a number of purine compounds to the cat submandibular salivary gland led to an increased blood flow. The threshold concentration of the most potent vasodilators, adenosine 5'-triphosphate (ATP) and adenosine 5'-diphosphate (ADP) was about 2 mumol/l. Adenosine and guanosine 5'-triphosphate (GTP) required about 25 mumol/l, adenosine 3',5'-cyclic monophosphate (cyclic AMP) 40 mumol/l, guanosine 5'-diphosphate (GDP) 125 mumol/l and dibutyryl guanosine 3',5' cyclic monophosphate (db cyclic GMP) 400 mumol/l. Dibutyryl cyclic AMP and cyclic GMP were ineffective. 2 The cyclic nucleotide phosphodiesterase inhibitors, theophylline, papaverine, quinine and 3-isobutyl-1-methylxanthine (IBMX), all acted as vasodilators. 3 When intra-arterial infusion of theophylline or IBMX was combined with sympathetic nerve stimulation, the vasodilatation observed after the stimulus ceased was significantly potentiated. 4 Theophylline and IBMX also potentiated the vasodilatation accompanying parasympathetic nerve stimulation and this response persisted after atropine. 5 These results are discussed in relation to the possible mediators of sympathetic and parasympathetic vasodilatation in the gland.     

Inhibition of phosphodiesterase 2 increases neuronal cGMP, synaptic plasticity and memory performance

An essential element of the signalling cascade leading to synaptic plasticity is the intracellular second messenger molecule guanosine 3',5'-cyclic monophosphate (cGMP). Using the novel, potent, and selective inhibitor Bay 60-7550, we show that the enzyme 3',5'-cyclic nucleotide phosphodiesterase type 2 (PDE2) is responsible for the degradation of newly synthesized cGMP in cultured neurons and hippocampal slices. Inhibition of PDE2 enhanced long-term potentiation of synaptic transmission without altering basal synaptic transmission. Inhibition of PDE2 also improved the performance of rats in social and object recognition memory tasks, and reversed MK801-induced deficits in spontaneous alternation in mice in a T-maze. Our data provide strong evidence that inhibition of PDE2 can improve memory functions by enhancing neuronal plasticity.     

N-ethylmaleimide inhibition of thrombin-induced platelet aggregation.

The data presented in this report show that N-ethylmaleimide (NEM) is a powerful inhibitor of thrombin-induced platelet aggregation. NEM increased guanosine 3', 5'-cyclic monophosphate (cGMP) and adenosine 3', 5'-cyclic monophosphate (cAMP) levels in intact cells. The inhibition of cAMP high-affinity phosphodiesterase and cGMP phosphodiesterase was implicated in the elevation of the cyclic nucleotides. NEM dose dependently blocked the thrombin-stimulated, but not the phorbol myristate acetate-dependent phosphorylation of the protein kinase C substrate pleckstrin. Myosin light chain phosphorylation was also inhibited by NEM. In addition, the sulphydryl reagent inhibited Ca2+ mobilisation induced by thrombin. The data indicate that phospholipase C activation by thrombin is interrupted by NEM at the level of receptor-mediated signal transduction.