9-(2-膦酰甲氧乙基)腺嘌呤及其口服前药阿地福韦双特戊酰氧甲酯的合成

报道了开环核苷酸类化合物 9 (2 膦酰甲氧乙基 )腺嘌呤 (PMEA)及其口服前药阿地福韦双特戊酰氧甲酯 (adefovirdipivoxil)的合成 ,并对文献报道的路线进行了改进 ,使制备方法更便捷 ,便于大量制备     

9－（2－膦酰甲氧乙基）腺嘌呤及其位置异构体3－（2－膦酰甲氧乙基）腺嘌呤的合成和抗病毒活性研究

９－（２－膦酰甲氧乙基）腺嘌呤及其位置异构体３－（２－膦酰甲氧乙基）腺嘌呤的合成和抗病毒活性研究刘晓辉，王琳，贯宝和，孔漫，张兴权，陶佩珍，陈鸿珊（中国医学科学院、中国协和医科大学药物研究所，北京１０００５０；中国医学科学院、中国协和医科大学医药生物...     

9-(2-磷酰甲氧乙基)腺嘌呤的亲脂性前药的合成及其肝细胞靶向载体

慢性乙肝疾病是肝实质细胞感染乙型肝炎病毒(HBV)所致,治疗不及时会引起肝硬化甚至肝癌。9-(2-磷酰甲氧乙基)腺嘌呤(PMEA)是抗HBV核苷类药物中较有前景的一个,但其只有不到5%为病灶区吸收,大多蓄积于肾脏从而引发肾中毒。因此,载体介导的PMEA向肝实质细胞的定向转递,对其提高抗HBV疗效和降低肾毒性无疑具有重大意义。脱唾液酸糖蛋白受体是肝实质细胞所特有的,它可识别包括乳糖残基在内的多种配体,这样人工合成的重组高密度脂蛋白(NeoHDL)经乳酰化(LacNeoHDL)即可为其所识别。强亲水性的PMEA通过一个酸不稳定的磷酰胺键以乙二胺…     

9-[2-(膦酰甲氧基)乙基]腺苷-钠盐的致突变性研究

目的评价9-[2-(膦酰甲氧基)乙基]腺苷-钠盐(PMEA-Na)的致突变性。方法采用组氨酸缺陷型鼠伤寒沙门氏菌回复突变试验(Am es试验)、中国仓鼠肺细胞(CHL)染色体畸变试验和小鼠骨髓微核试验,观察PMEA-Na的致突变性。结果PMEA-Na在50~5000μg.皿-1剂量范围内,加与不加S9活化系统条件下,对TA97、TA98、TA100、TA102四种菌株的回变菌落数均未超过自发对照的2倍,即Am es试验结果为阴性;染色体畸变试验中,当药物浓度为48、24、12、6 mg.L-1时,活化条件下各浓度细胞的染色体畸变率均低于5%。在非活化条件下,药物浓度为48 mg.L-1培养48 h时,染色体畸变率为10%,因此染色体畸变试验结果为阳性;小鼠静脉注射PMEA-Na剂量为1 000、500、250 mg.kg-1时,骨髓中含微核的嗜多染红细胞数明显增加,即微核试验结果为阳性。结论在本实验条件下,PMEA-Na具有潜在的致突变性。     

9-[2-(膦酰甲氧基)乙基]腺嘌呤一钠盐在比格犬体内的毒代动力学和毒理学研究

目的为9-[2-(膦酰甲氧基)乙基]腺嘌呤一钠盐(PMEA-Na)重复给药的毒性研究提供毒代动力学资料。方法采用液相色谱质谱联用方法测定样品中的药物浓度,数据经统计矩方法处理得到毒代动力学参数,并完成血清生化学及组织病理学检测。结果比格(Beagle)犬静脉单次及多次给药(14 d,每日1次)后,在给药剂量范围内, AUC均表现为剂量依赖性。在1.0, 3.0与6.0 mg·kg-1PMEA-Na时,AUC分别为(2.3±0.5),(8.4±1.6),(17.5±3.7)mg·L-1·h(单剂量)和(5.0±0.4),(15.9±3.2),(30.3±4.7) mg·L-1·h(多剂量)。PMEA-Na主要经肾脏排出体外,且给药14 d后肾功能受损药物排泄能力降低。与对照组比较, 6.0 mg·kg-1组血清生化学检测指标丙氨酸氨基转换酶、总胆红素、尿素氮、肌酐及甘油三酯均升高,葡萄糖水平下降。6.0 mg·kg-1组的组织病理学检查发现肝脏和肾脏有明显的病理形态学改变。结论比格犬经静脉多次给PMEA-Na 14 d后出现毒性反应,毒性靶器官主要为肾脏和肝脏。     

9-［2-(膦酰甲氧基)乙基］腺嘌呤一钠盐在比格犬体内的毒代动力学和毒理学研究

目的 为9-［2-(膦酰甲氧基)乙基］腺嘌呤一钠盐（PMEA-Na）重复给药的毒性研究提供毒代动力学资料。方法 采用液相色谱质谱联用方法测定样品中的药物浓度，数据经统计矩方法处理得到毒代动力学参数，并完成血清生化学及组织病理学检测。结果 比格(Beagle)犬静脉单次及多次给药（14 d，每日1次）后，在给药剂量范围内，AUC均表现为剂量依赖性。在1.0, 3.0 与6.0 mg·kg^-1 PMEA-Na时，AUC分别为（2.3±0.5），（8.4±1.6），（17.5±3.7）mg·L^-1·h(单剂量)和（5.0±0.4），（15.9±3.2），(30.3±4.7) mg·L^-1·h（多剂量）。PMEA-Na主要经肾脏排出体外，且给药14 d后肾功能受损药物排泄能力降低。与对照组比较, 6.0 mg·kg^-1组血清生化学检测指标丙氨酸氨基转换酶、总胆红素、尿素氮、肌酐及甘油三酯均升高, 葡萄糖水平下降。6.0 mg·kg^-1组的组织病理学检查发现肝脏和肾脏有明显的病理形态学改变。结论 比格犬经静脉多次给PMEA-Na 14 d后出现毒性反应，毒性靶器官主要为肾脏和肝脏。     

2-(2-甲氧苯氧)乙胺的合成

2-(2-甲氧苯氧)乙胺是合成某些β-受体阻断剂的重要中间体。我们探讨了几种不同的制备途径,发现将愈创木酚与1,2-二氯乙烷(或1,2-二溴乙烷)反应的单取代卤代物转化为叠氮化物,通过催化氢化,可以获得产率高,纯度好的伯胺。目标物也可以通过Gabriel反应或通过相应睛的还原制得,但是叠氮化合物途径是一条经济而安全的路线。     

4,4-二(二乙氧膦酰)-丁酸的合成

目的：探讨4，4-二（二乙氧膦酰）-丁酸的合成研究。方法：以亚甲基二膦酸四乙酯为原料，经5步反应合成目标物。结果：总收率为64％。结论：该方法操作简单易行，是合成目标化合物的较好方法。     

2-(甲氨基)乙基糖苷的高效合成

目的 通过化学合成的手段进行N-甲基乙基糖苷的高效合成。方法 以单糖为原料,首先制备苯甲酰化的三氯乙酰亚胺酯糖基供体,然后与苄氧基羰基(Cbz)保护的2-N-甲氨基乙醇进行糖苷化反应,最后依次脱除苯甲酰基和苄氧羰基保护基团,得到N-甲基乙基糖苷目标化合物。结果 基于此策略合成了葡萄糖、半乳糖、木糖、岩藻糖和阿拉伯糖的N-甲基乙基糖苷,6步总收率为60%~74%;结构均经_¹H NMR,_¹³C NMR和HR-MS(ESI)表征。结论 本文建立的合成N-甲基乙基糖苷的方法具有简单高效、立体选择性好和适用性广的特点。     

(S)-2-甲氧亚胺基-2-呋喃乙酸的合成

以呋喃为原料，经乙酰化、肟重排、肟化合成(S)-2-甲氧亚胺基-2-呋喃乙酸。总收率达34％。     

Phosphorylation of 9-(2-phosphonomethoxyethyl)adenine and 9-(S)-(3-hydroxy-2-phosphonomethoxypropyl)adenine by AMP(dAMP) kinase from L1210 cells.

Acyclic nucleotide analogues 9-(2-phosphonomethoxyethyl)adenine (PMEA) and 9-(S)-(3-hydroxy-2-phosphonomethoxypropyl)adenine ((S)-HPMPA) which display potent antiviral activity are transformed in the cells to their mono- and disphosphoryl derivatives. We purified from mouse L1210 cells the enzyme that in two steps phosphorylates PMEA and (S)-HPMPA to their diphosphoryl derivatives and found that it co-purifies with AMP(dAMP) kinase activity; the best substrates of this enzyme were AMP, ADP and dAMP. Other nucleoside 5'-triphosphates or creatine phosphate could not be substituted for ATP as a phosphate donor. Our results also indicated that at least one other enzyme (creatine kinase) is capable of transforming the monophosphoryl derivatives of the studied compounds to their respective diphosphates.     

腺嘌呤衍生物的合成及体外抗疱疹病毒活性

以腺嘌呤为母体,在其9位引入活性基团N-取代缩氨基硫脲(TSC),设计合成了12个6-氨基-9(N^4'-取代乙醛缩氨基硫脲)嘌呤衍生物(4a～1),并进行了体外抗单纯疱疹病毒I型(HSV-1),II型(HSV-2),水痘-带状疱疹病毒(VZV)活性试验及细胞毒性试验。结果表明,除化合物4e及4f对HSV-1及VZV有较高活性外,其余化合物对上述两种病毒的活性均不明显。另外,将4e与4f分别与无环鸟苷(ACV)联合用药,其最小抑制浓度(MIC)及细胞毒性(MCC)均显著下降。     

Immunomodulatory activity of 9-(2-phosphonylmethoxyethyl)adenine (PMEA), a potent anti-HIV nucleotide analogue, on in vivo murine models.

In order to evaluate the influence of antiviral nucleoside analogues upon the natural immune system, we investigated the immunomodulatory activity of 9-(2-phosphonylmethoxyethyl)adenine (PMEA), a nucleotide analogue with potent anti-HIV and anti-herpes activity, in a murine system. C57BL/6 mice were inoculated intraperitoneally with 10, 25 and 50 mg PMEA/kg. Mononuclear cells were isolated from their spleens, and some natural immune functions were evaluated. The results show that PMEA significantly increases the levels of natural killer (NK)-cell cytotoxicity. We also found that alpha/beta IFN production was substantially increased in PMEA-treated mice, while both IL-1 and IL-2 production was decreased. Thus, PMEA can increase some natural immunity functions, such as NK activity and IFN production. These results suggest that PMEA might be active in vivo against HIV and herpes viruses both as an immunomodulator and as an antiviral compound.     

Synthesis of a Lipophilic Prodrug of 9-(2-Phosphonylmethoxyethyl)adenine (PMEA) and Its Incorporation into a Hepatocyte-Specific Lipidic Carrier

Purpose. 9-(2-Phosphonylmethoxyethyl)adenine (PMEA), a potent inhibitor of Hepatitis B virus replication, is in vivo hardly taken up by parenchymal liver cells (the site of infection). Our aim is to examine whether lactosylated reconstituted HDL (LacNeoHDL), a lipidic particle that is specifically internalized by parenchymal liver cells, is a suitable carrier for the selective delivery of PMEA to this cell type. Methods. To incorporate PMEA into LacNeoHDL, we synthesized a lipophilic prodrug (PMEA-LO) by coupling PMEA via an acid-labile phosphonamidate bond to lithocholic acid-3-oleate. Results. The yield of the synthesis was 52% ([³H]PMEA-LO: 24%). [³H]PMEA-LO readily incorporated into LacNeoHDL (13 molecules/ particle) without affecting the size and net negative charge of the carrier. Further, incubation studies at lysosomal pH showed [³H]PMEA was completely released from the carrier whereas, at neutral pH or in plasma, appreciable release was not observed. Conclusions. The conjugation of PMEA with lithocholic acid-3-oleate results in a lipophilic prodrug that readily associates with LacNeoHDL. The association of the prodrug does not affect the physico-chemical properties of the particle, and PMEA is released from the carrier at lysosomal pH. These findings indicate that by using the prodrug approach, LacNeoHDL is a suitable carrier to deliver PMEA to parenchymal liver cells.     

Safety of 9-(2-phosphonylmethoxyethyl)adenine (PMEA) in patients with human immunodeficiency virus infection

The compound 9-(2-phosphonylmethoxyethyl)adenine (PMEA) is a potent inhibitor of a number of viruses in vitro, such as human immunodeficiency virus types 1 and 2, herpes simplex virus types 1 and 2, hepatitis B virus, cytomegalovirus, and Epstein-Barr virus. PMEA also proved to be effective in vivo against feline immunodeficiency virus in cats and simian immunodeficiency virus in rhesus monkeys. In an open, non-placebo-controlled trial, the safety of weekly doses of PMEA in 10 patients with acquired immunodeficiency syndrome (AIDS) or AIDS-related complex was studied for a period of 11 weeks. CD4+ T-Cell counts at baseline were between 10 and 450/mm³. The drug was administered intravenously at a dose of 1000 mg. No serious side-effects were seen. On one occasion one patient showed alanine aminotransferase and aspartate aminotransferase levels 5 times higher than the upper limit of normal and another patient showed on one occasion aspartate aminotransferase levels 5 times higher than the upper limit of normal. In another patient serum amalyse levels increased, on one occasion 1.5 times above the upper limit of normal. An improvement in general well-being was reported by all patients. For patients with a CD4+ T-cell count > 100/mm³ at baseline, the CD4+ T-cell count increased from a mean of 283/mm³ at baseline to a mean of 448/mm³ at the end of the study. Repeat infusions of PMEA at a dose of 1000 mg were safe and well tolerated. Our results suggest that PMEA, administrated according to this treatment schedule, may be effective in treating patients with human immunodeficiency virus infection.     

Comparison of the Disposition of Ester Prodrugs of the Antiviral Agent 9-(2-phosphonylmethoxyethyl)adenine [PMEA] in Caco-2 Monolayers

Purpose. To evaluate the potential of several bis-ester prodrugs of the antiviral agent 9-(2-phosphonylmethoxyethyl)adenine (PMEA, adefovir) to enhance the oral absorption of PMEA. Methods. Caco-2 monolayers were used to estimate intestinal transport and metabolism of the bis(pivaloyloxymethyl)-ester [bis(POM)-] and a series of bis(S-acyl-2-thioethyl)-esters [bis(SATE)-] of PMEA. An LC-MS method was used for the identification of unknown metabolites which were formed from the SATE-esters. Results. During transport across Caco-2 monolayers, all esters were extensively degraded as could be concluded from the appearance of the mono-ester and free PMEA in apical as well as basolateral compartments. Incubation of SATE-esters with the monolayers resulted in the formation of two additional metabolites, which were identified as 2-thioethyl-PMEA and its dimerisation product. All ester prodrugs resulted in enhanced transepithelial transport of total PMEA (i.e. the bis-esters and their corresponding metabolites, including PMEA), but significant differences could be observed between the various esters. Transport of total PMEA ranged from 0.4 ± 0.1 % for the bis[S(methyl) ATE]-ester to 15.3 ± 0.9% for the more lipophilic bis[S(phenyl)ATE]-PMEA. A relationship between total transport of the esters and their lipophilicity (as estimated by their octanol/water partition coefficient) was established (r² = 0.87). Incubation of prodrug esters with homogenates from Caco-2 cells showed large differences in susceptibility of the compounds to esterases, the half-lives of the bis-esters varying from 4.3 ± 0.3 min for the bis[S(phenyl)ATE]-PMEA to 41.5 ± 0.8 min for its methyl analogue. In addition, intracellularly formed PMEA was observed to be further converted by the cells to the diphosphorylated PMEA (PMEApp). Conclusions. Several SATE-esters of PMEA can be considered as potential alternatives to bis(POM)-PMEA, due to enhanced epithelial transport, sufficient chemical and enzymatic stability and adequate release of PMEA. Toxicological studies as well as in vivo experiments are required in order to further explore the potential of those SATE-esters as prodrugs for oral delivery of PMEA.     

Binding of [H]MSX-2 (3-(3-hydroxypropyl)-7-methyl-8-(m-methoxystyryl)-1-propargylxanthine) to rat striatal membranes — a new, selective antagonist radioligand for A2A adenosine receptors

The present study describes the preparation and binding properties of a new, potent, and selective A_2A adenosine receptor (AR) antagonist radioligand, [³H]3-(3-hydroxypropyl)-7-methyl-8-(m-methoxystyryl)-1-propargylxanthine ([³H]MSX-2). [³H]MSX-2 binding to rat striatal membranes was saturable and reversible. Saturation experiments showed that [³H]MSX-2 labeled a single class of binding sites with high affinity (K_d=8.0 nM) and limited capacity (B_max=1.16 fmol·mg⁻¹ of protein). The presence of 100 μM GTP, or 10 mM magnesium chloride, respectively, had no effect on [³H]MSX-2 binding. AR agonists competed with the binding of 1 nM [³H]MSX-2 with the following order of potency: 5′-N-ethylcarboxamidoadenosine (NECA)>2-[4-(carboxyethyl)phenylethylamino]-5′-N-ethylcarboxamidoadenosine (CGS-21680)>2-chloroadenosine (2-CADO)>N⁶-cyclopentyladenosine (CPA). AR antagonists showed the following order of potency: 8-(m-bromostyryl)-3,7-dimethyl-1-propargylxanthine (BS-DMPX)>1,3-dipropyl-8-cyclopentylxanthine (DPCPX)>(R)-5,6-dimethyl-7-(1-phenylethyl)-2-(4-pyridyl)-7H-pyrrolo[2,3-d]pyrimidine-4-amine (SH-128)>3,7-dimethyl-1-propargylxanthine (DMPX)>caffeine. The K_i values for antagonists were in accordance with data from binding studies with the agonist radioligand [³H]CGS21680, while agonist affinities were 3–7-fold lower. [³H]MSX-2 is a highly selective A_2A AR antagonist radioligand exhibiting a selectivity of at least two orders of magnitude versus all other AR subtypes. The new radioligand shows high specific radioactivity (85 Ci/mmol, 3150 GBq/mmol) and acceptable nonspecific binding at rat striatal membranes of 20–30%, at 1 nM.     

Transport,Uptake, and Metabolism of the Bis(pivaloyloxymethyl)-Ester Prodrug of 9-(2- Phosphonylmethoxyethyl)Adenine in an In Vitro Cell Culture System of the Intestinal Mucosa (Caco-2)

Purpose. To evaluate intestinal transport, uptake and metabolism characteristics of the bis(pivaloyloxymethyl)-ester [bis(POM)-ester] of the antiviral agent 9-(2-phosphonylmethoxyethyl)adenine [PMEA]. Methods. Intestinal transport, uptake and metabolism of bis(POM)-PMEA were studied using an in vitro cell culture system of the intestinal mucosa (Caco-2 monolayers). Concentrations of bis(POM)-PMEA and its metabolites mono(POM)-PMEA and PMEA were determined using a reversed-phase HPLC method. Enzymatic stability of bis(POM)-PMEA was evaluated by incubation with purified liver carboxylesterase, homogenates of Caco-2 cells and scraped pig small intestinal mucosa. Results. The use of bis(POM)-PMEA as a prodrug of PMEA resulted in a significant increase in transport of total PMEA [bis(POM)-PMEA, mono(POM)-PMEA and PMEA] across Caco-2 monolayers. While transepithelial transport of PMEA (500 M) was lower than 0.1% during a 3 hr incubation period, transport of total PMEA after addition of bis(POM)-PMEA (100 M) amounted to 8.8% over the same incubation period. Only 23% of the amount transported appeared as intact bis-ester at the basolateral side, while 33% of this amount was free PMEA and 44% was mono(POM)-PMEA, suggesting susceptibility of the prodrug to chemical and enzymatic degradation. Uptake studies revealed that only negligible amounts of bis(POM)-PMEA (< 0.2%) were present inside the cells. Very high intracellular concentrations of PMEA were found 1.2 mM, after a 3 hr incubation with 50 M bis(POM)-PMEA), which suggests that PMEA was trapped inside the cells probably due to its negative charge. This explains that efflux of PMEA was relatively slow (25% of the intracellular amount in 3 hr). Enzymatic degradation of the prodrug by carboxylesterase was confirmed by incubation of bis(POM)-PMEA with purified enzyme (K_m = 87 M and V_max = 9.5 M/min). Incubation of bis(POM)-PMEA (10 M) with cell homogenate of Caco-2 monolayers and pig small intestinal mucosa produced similar degradation profiles. Conclusions. The use of the bis(POM)-prodrug significantly enhances the intestinal permeability of PMEA. Intracellular trapping of PMEA in the intestinal mucosa may result in slow release of PMEA to the circulation after oral administration of bis(POM)-PMEA.     

Synthesis and in vitro evaluation of a phosphonate prodrug: bis(pivaloyloxymethyl) 9-(2-phosphonylmethoxyethyl)adenine.

9-(2-Phosphonylmethoxyethyl)adenine (PMEA; 1) was acylated with chloromethyl pivalate to afford bis(pivaloyloxymethyl) PMEA (2). The ester prodrug demonstrated enhanced in vitro potency against HSV-2 greater than 150-fold higher than the parent compound. The antiviral activity of 2 was 50-fold better than PMEA against HSV-1, and equipotent against HIV and HCMV. The toxicity of 2 was studied in both resting and growing cells.