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,N~2-二甲胺基甲烯基-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。N~2-二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。     

甘草叶中两个新异戊烯基黄酮类化合物

自乌拉尔甘草(Glycyrrhiza uralensis Fisch.)的干燥叶中分离到三个黄酮类化合物。经化学方法和光谱(UV,MS,¹HNMR)数据分析,分别确定为5,7,3′,4′-四羟基-3-甲氧基-5′-异戊烯基黄酮(Ⅰ),5,6,3′,4′-四羟基-3-甲氧基-6′-异戊烯基黄酮(Ⅱ)和槲皮素(Ⅲ)。Ⅰ和Ⅱ是新化合物,分别命名为乌拉尔醇-3-甲醚(uralenol-3-methylether)和乌拉尔素(uralene)。Ⅲ在本种植物中为首次报道。     

3-(R)-(碱基)-4-(S)-羟基-5-(R)-羟亚甲基四氢呋喃的合成及抗肿瘤活性

目的：研究一系列3-(R)-单脱氧异核苷的合成和抗肿瘤活性。方法和结果：由L-木糖出发,合成了环氧化物5-(R)-二甲氧甲基-3(S),4(S)-环氧四氢呋喃4;在碱性条件下,利用嘌呤的N⁹位或嘧啶的N¹位对环氧化物进行亲核进攻,得到一系列3-(R)-单脱氧异核苷5a-d和6a-d;并进行了体外抗肿瘤活性筛选。结论：其中3-(R)-单脱氧异核苷5a-d为首次报道;同已报道的3-(S)-单脱氧异核苷合成方法相比,路线缩短,收率提高。在体外抗肿瘤和端粒酶抑制活性筛选中,只有化合物6a显示了对BIU细胞较弱的抑制活性,其余均未显示有意义的抗肿瘤活性和端粒酶抑制活性。     

胆甾醇衍生的几种含硫化合物的合成

1.由3β-溴代-△⁵-胆甾烯与β-氨基乙醇反应,分离得到三种产物:3β-(2′-羟乙基氨基)-△⁵-胆甾烯;3α-(2′-羟乙基氨基)-△⁵-胆甾烯与6-(2′-羟乙基氨基)-3:5-环胆甾烷。2.3β-(2′-羟乙基氨基)-△⁵-胆甾烯经亚硫酰氯作用后,与异硫脲反应可获得3β(2′-异硫脲代乙氨基)-△⁵-胆甾烯。继续水解得3β-(2′-巯乙基氨基)-△⁵-胆甾烯。它们可分别视为N取代的半胱胺或β-氨乙基异硫脲的衍生物。3.由3β-巯基-△⁵-胆甾烯与β-溴代乙胺作用,制得3β-(2′-氨乙基巯基)-△⁵-胆甾烯。后者可视为S取代的半胱胺衍生物。3β-(3′-邻苯二甲酰亚胺丙基代巯基)-△⁵-胆甾烯与3β-(3′,4′,5′-三甲氧基苯甲酰巯基)-△⁵-胆甾烯也由类似方法合成。     

双(2,6-哌嗪二酮)类抗肿瘤药物的研究:2,3-二乙酰氧基-1,4-二(3′,5′-二酮-N4′-取代哌嗪甲基)苯的合成

Seventeen compounds having the structure of 2,3-diacetoxy-1,4-bis(3′,5′- dioxo-N⁴′-substituted piperazinyl methyl)benzene were designed and synthesized based on chelation hypothesis. Their antitumor activities on P388 cells,Hep cells and SGC 7901 cells in vitro were tested. Preliminary results showed that compound 4e has potent antitumor effect against P388 cells and.Hep cells in vitro.     

甘草叶中黄酮类成分的化学研究

自甘草(Glycyrrhiza uralensis Fisch)的叶中分离到四个黄酮类化合物。根据理化性质,光谱(UV,MS,¹HNMR)数据分析,分别确定结构为3,5,7,3′,4′-五羟基-5′-异戊烯基黄酮(Ⅰ),3,6,7,3′,4′-五羟基-2′-异戊烯基黄酮(Ⅱ),5,7,3′,4′-四羟基-5′-异戊烯基二氢黄酮(Ⅲ)和槲皮素-3,3′-二甲醚(Ⅳ)。其中,Ⅰ,Ⅱ和Ⅲ是新化合物,分别命名为乌拉尔醇(uralenol),新乌拉尔醇(neouralenol)和乌拉尔宁(uralenin)。Ⅳ在本属植物中为首次发现。Ⅲ为甘草叶中的主要黄酮类成分。本文解释了B环某些裂解碎片丰度与异戊烯基和氧取代基相对位置的关系。     

海风藤中新木脂素类PAF拮抗活性成分的研究

自中药海风藤[Piper kadsura (Choisy)Ohwi]的藤茎中又分离得到四个macrophyllin型双环[3,2,1]辛烷类新木脂素,经光谱分析及衍生物的制备,确定化合物Ⅰ和Ⅲ为新结构,命名为风藤素K(kadsurenin K)和风藤素L(kadsurenin L),其化学结构分别为7R,8R,3′R,5′R-△^8′-3,5′-二甲氧基-4-羟基-2′,3′,4′,5′-四氢-2′,4′-氧-7.3′,8.5′-新木脂素(Ⅰ)和7R,8R,3′S,4′R,5′R-△^8′-3,4,5′-三甲氧基-4′-乙酰氧基-2′,3′,4′,5′-四氢-2′-氧-7.3′,8.5′-新木脂素(Ⅲ)。化合物Ⅱ和Ⅳ分别为已报道过的风藤素C和风藤素B。化合物Ⅰ～Ⅳ均有明显的PAF受体拮抗活性。     

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     

羟甲芬太尼立体异构体的晶体结构

对强效镇痛剂羟甲芬太尼的两个光学异构体体cis-(3R,4S,2′R)-羟甲芬太尼(I)和trans-(3R,4R,2′S)-羟甲芬太尼(Ⅱ)进行了X-射线衍射晶体结构分析。两个异构体均有一个sp³N(l)原子和一个sp²N(7)原子。哌啶环呈椅式构象,顺式异构体I的3-甲基处于直立键,4-N-苯基丙酰胺基处于平伏键;反式异构体II的3-甲基与4-N-苯基丙酰胺基均处于平伏键。在I分子中,C(4)原子与4-丙酰胺基组成的平面与N-苯环平面近似相互垂直,而在II中,两平面的二面角近似为100℃。两异构体分子中均存在分子内氢键O(1)一H…N(1),反式异构体II还存在分子间氢键O(1)一H(A)…O(2)(B)。     

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.     

Cyclic phosphates of formycin.

The syntheses of N1- and N2-isopropylformycin (10, 11), formycin 3',5'-cyclic and 2',3'-cyclic phosphate (3,7) and their N-methyl and N-isopropyl derivatives (13, 15, 19, 23) are described. It was observed that substitution at N1 or N2 with a bulky alkyl group or cyclic phosphorylation of the ribose moiety made formycin resistant to adenosine deaminase.     

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)     

Nitric oxide protects murine embryonic liver cells (BNL CL.2) from cytotoxicity induced by glucose deprivation

We investigated the protective effects of nitric oxide on cell death of murine embryonic liver cells (BNL CL.2) after glucose deprivation. Endogenous nitric oxide production by BNL CL.2 cells was induced by 6 hr pretreatment with interferon-gamma and lipopolysaccharide. We used sodium nitroprusside and S-nitroso-L-glutathione as exogenous nitric oxide-generating compounds. All agents were used at doses that did not show direct cytotoxicity as measured by crystal violet staining assay. In the BNL CL.2 cells, the viability dropped very steeply after 24 hr incubation with glucose-free media. Endogenous nitric oxide produced by treatment of the cells with interferon-gamma and lipopolysaccharide protected the cells from glucose deprivation-induced cytotoxicity, but did not protect them in the presence of the nitric oxide synthesis inhibitor, N(G)-monomethyl-L-arginine. Exogenous nitric oxide protected the cells from glucose deprivation-induced cytotoxicity in a concentration-dependent manner. Cytoprotection by nitric oxide donors was abolished by the use of nitric oxide scavenger, 2-phenyl-4,4,5,5,-tetramethylimidazole, but not by the soluble guanosine cyclase inhibitor, 1H-[1,2,4]oxadiazole[4,3-a]quinoxalin-1-one. In addition, cytoprotective effects comparable to endogenous or exogenous nitric oxide were not observed when the cells were incubated with dibutyl guanosine 3',5'-cyclic monophosphate. Based upon these results, we suggest that nitric oxide may enhance the cell survival of BNL CL.2 cells after glucose deprivation via a guanosine 3',5'-cyclic monophosphate-independent pathway.     

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)     

Inhibition of cyclic GMP-dependent protein kinase-mediated effects by (Rp)-8-bromo-PET-cyclic GMPS.

1. The modulation of the guanosine 3':5'-cyclic monophosphate (cyclic GMP)- and adenosine 3':5'-cyclic monophosphate (cyclic AMP)-dependent protein kinase activities by the diastereomers of 8-bromo-beta phenyl-1, N2-ethenoguanosine 3':5'-cyclic monophosphorothioate, ((Rp)- and (Sp)-8-bromo-PET-cyclic GMPS) was investigated by use of purified protein kinases. In addition, the effects of (Rp)-8-bromo-PET-cyclic GMPS on protein phosphorylation in intact human platelets and on [3H]-noradrenaline release and neurogenic vasoconstriction in electrical field stimulated rat tail arteries were also studied. 2. Kinetic analysis with purified cyclic GMP-dependent protein kinase (PKG) type I alpha and I beta, which are expressed in the rat tail artery, revealed that (Rp)-8-bromo-PET-cyclic GMPS is a competitive inhibitor with an apparent Ki of 0.03 microM. The activation of purified cyclic AMP-dependent protein kinase (PKA) type II was antagonized with an apparent Ki of 10 microM. 3. In human platelets, (Rp)-8-bromo-PET-cyclic GMPS (0.1 mM) antagonized the activation of the PKG by the selective activator 8-(4-chlorophenylthio)-guanosine 3':5'-cyclic monophosphate (8-pCPT-cyclic GMP; 0.2 mM) without affecting the activation of PKA by (Sp)-5, 6-dichloro-1-beta-D-ribofurano-sylbenzimidazole- 3':5'-cyclic monophosphorothioate ((Sp)-5,6-DCl-cyclic BiMPS; 0.1 mM). 4. (Rp)-8-bromo-PET-cyclic GMPS was not hydrolysed by the cyclic GMP specific phosphodiesterase (PDE) type V from bovine aorta but potently inhibited this PDE. 5. The corresponding sulphur free cyclic nucleotide of the two studied phosphorothioate derivatives, 8-bromo-beta-phenyl-1, N2-ethenoguanosine-3':5'-cyclic monophosphate (8-bromo-PET-cyclic GMP), had no effect on electrically-induced [3H]-noradrenaline release but concentration-dependently decreased the stimulation-induced vasoconstriction. (Rp)-8-bromo-PET-cyclic GMPS (3 microM) shifted the vasoconstriction response to the right without affecting stimulation evoked tritium overflow. 6. The NO donor, 3-morpholinosydnonimine (SIN-1) relaxed rat tail arteries precontracted with phenylephrine (1 microM). The SIN-1 concentration-relaxation curve was shifted in a parallel manner to the right by (Rp)-8-bromo-PET-cyclic GMPS, suggesting that the relaxation was mediated by a cyclic GMP/PKG-dependent mechanism. 7. The [3H]-noradrenaline release-enhancing effect and stimulation-induced decrease in vasoconstriction of forskolin were unaffected by (Rp)-8-bromo-PET-cyclic GMPS. Moreover, the forskolin concentration-relaxation curve was not changed in the presence of the PKG inhibitor, suggesting a high selectivity in intact cells for PKG- over PKA-mediated effects. 8. The results obtained indicate that (Rp)-8-bromo-PET-cyclic GMPS presently is the most potent and selective inhibitor of PKG and is helpful in distinguishing between cyclic GMP and cyclic AMP messenger pathways activation. Therefore, this phosphorothioate stereomer may be a useful tool for studying the role of cyclic GMP in vitro.