新型磷酸二酯酶特异性抑制剂的发现及识别机制

磷酸二酯酶(PDE)通过催化水解细胞内第二信使(环磷酸腺苷cAMP,或环磷酸鸟苷cGMP),以降低细胞内cAMP或cGMP的浓度,从而中止这两个第二信使所传导的生理作用。PDEs作为新型的药物作用靶点,参与多种疾病的治疗,已成为新药研发的重要靶点。截至目前,已有多个PDE抑制剂药物上市(PDE5:5个,治疗性功能障碍和肺动脉高压;PDE4:3个,治疗慢性阻塞性肺病等),其中最出名的案例是用于治疗男性勃起功能障碍和肺动脉高压的PDE5抑制剂西地那非。然而,低选择性是这些PDE抑制剂的主要缺陷。近期我们针对PDE4,5,8,9和10等亚型,通过基于结构的药物分子设计,合成并发现多类高选择性的抑制剂。如,1)合成近150个PDE9抑制剂,从中发现抑制效应最强的高选择性先导结构3r。3r(IC_(50)=0.6 nmol·L~(-1),对PDE1选择性为788倍),活性和选择性均明显优于临床Ⅱ期的辉瑞抑制剂PF-04447943。通过晶体结构分析,发现3r与PDE9特有残基Y424形成氢键,是其具有高倍选择性的结构基础,这为PDE9高选择性抑制剂提供了新的设计策略。此外共晶结构还揭示3r和A452形成一个氢键,而PF-04447943未显示这种结合模式。通过设计与A452形成氢键,可提高化合物的抑制效应。2)合成近100个多个PDE5抑制剂,从中发现抑制剂从中发现抑制效应最强的高选择性先导结构1610。1610(IC_(50)=5.0 nmol·L~(-1),对PDE6选择性为100倍)的抑制活性与辉瑞药物西地那非相当,但选择性均明显优于西地那非(对PDE6选择性为2~3倍),动物实验也显示该类药物的抗动脉高压效果明显优于对照药物西地那非。通过分子模拟分析,发现1610进入靶标结构的Q2口袋,是1610具有100倍选择性的结构基础,这为PDE5高选择性抑制剂提供了新的设计策略。     

PDE4/PDE7双重抑制剂的研究进展

目的为进一步研究磷酸二酯酶抑制剂提供参考。方法对磷酸二酯酶4(PDE4)和磷酸二酯酶7(PDE7)的组织分布、生理功能、催化区域的结构特点和PDE4/PDE7双重抑制剂研发的最新进展进行综述。结果 PDE4/PDE7双重抑制剂具有显著的抗炎作用,且能够避免单一性的PDE4选择性抑制剂药物具有如恶心、呕吐等副作用。结论 PDE4/PDE7双重抑制剂有希望成为新一代的抗炎药物。     

选择性磷酸二酯酶同功酶抑制剂与支气管哮喘的治疗

目前认为茶碱类药物毒副作用的产生与其非特异性地抑制磷酸二酯酶 (PDE)同工酶有关。为避免PDE同工酶被广泛抑制所产生的毒副作用 ,近年来选择性PDE同功酶抑制剂成为人们研究的热点。与哮喘治疗有关的主要是选择性PDE4 ,PDE3/PDE4或PDE3抑制剂。大量的临床前研究证明它们具有免疫调节和抗炎、舒张支气管平滑肌等作用。早期临床研究也表明它们治疗哮喘有效。虽然它们仍存在副作用较多且疗效不佳等缺点 ,但可以相信 ,随着人们对PDE同工酶认识的更进一步深入 ,必将会开发出疗效更佳、更安全的抑制剂 ,为哮喘的治疗提供一种新的选择     

磷酸二酯酶9及其抑制剂的研究进展

目的为磷酸二酯酶9(phosphodiesterase 9,PDE 9)的研究与开发提供参考。方法查阅PDE 9及其抑制剂的研究开发现状的多篇相关文献,进行整理和归纳。结果大多数PDE9抑制剂都能选择性地在体外和体内抑制PDE 9,并取得较好的药理活性。结论PDE 9将成为药物治疗的新一代靶点,其抑制剂的研究与开发具有广阔的发展前景。     

cGMP特异性磷酸二酯酶5活性及其抑制剂的研究

目的研究以cGMP为特异底物的磷酸二酯酶 5 (PDE5 )的水解酶活性及PDE5选择性抑制剂西地那非(sildenafil)的抑制作用。方法以牛阴茎海绵体为原料 ,通过快速蛋白液相系统分离纯化得到PDE同工酶 ,然后以3 H cGMP为底物 ,经纯化的PDE同工酶催化水解为3 H GMP ,进一步在含 5′ 核苷酸酶的蛇毒液作用下 ,脱去 5′ 磷酸生成3 H 鸟苷 ,在闪烁剂激发下测定3 H 鸟苷的变化 ,绘制PDE活性曲线。以不同剂量的PDE5选择性抑制剂西地那非作用于PDE5 ,经DixonPlots法处理结果以观察西地那非的抑制效应。结果由牛阴茎海绵体纯化得到三个PDE同工酶峰 ,其中第三个峰对cGMP水解活性最强 ,且西地那非对第三峰抑制作用明显。结论海绵体中的PDE以cGMP 特异的PDE5为主 ,西地那非是PDE5的选择性抑制剂 ,通过以上实验观察可初步确定第三峰为PDE5 ,其结果与文献报道相符。     

磷酸二酯酶参与认知与情绪调节的研究进展

磷酸二酯酶(PDE)催化水解cAMP和cGMP,是细胞内降解cAMP和cGMP的唯一途径。PDE是一个多基因大家族酶,包含11型不同家族,它们的结构,分布以及调节方式对抑制剂的敏感性都不同。PDE选择性抑制剂可通过抑制cAMP或cGMP水解来调节学习记忆障碍等中枢神经系统疾病。因此,PDE被认为在中枢神经系统疾病的治疗上具有重要地位。本综述介绍目前PDE参与学习记忆障碍这一中枢神经系统疾病调节的研究进展,而且PDE作为中枢神经系统疾病的治疗靶点,研究其选择性抑制剂具有重要的意义。     

磷酸二酯酶4抑制剂临床及安全性研究进展

磷酸二酯酶4 (phosphodiesterase 4, PDE4)是磷酸二酯酶家族中重要成员之一,可特异性水解环磷酸腺苷(cyclic adenosine monophosphate, cAMP),通过改变cAMP浓度引发下游磷酸化级联反应,与多种疾病密切相关。靶向PDE4的抑制剂临床研究包括呼吸系统疾病、自身免疫性疾病、中枢神经系统疾病及皮肤病等多种疾病领域。但是在已上市的PDE4抑制剂临床研究中发现,大多数药物的恶心、呕吐等胃肠道不良反应发生率较高,限制了其临床应用。因此本综述总结了已上市PDE4抑制剂的临床进展及安全性问题,结合PDE4蛋白结构分析、PDE4抑制剂的作用机制及相关不良反应机制研究,阐述了PDE4抑制剂产生不良反应的主要原因,旨在为开发安全有效的PDE4抑制剂提供参考。     

选择性磷酸二酯酶抑制剂研究进展

磷酸二酯酶 (PDEs)迄今已报道有 9个基因家族 ,每个家族又包括多个亚家族。PDEs分布于多个组织中 ,其抑制剂具有广泛的生理作用。其中 ,PDE 4抑制剂被认为是作用于细胞内靶点的新型免疫调节、抗炎药物。新型PDE 5抑制剂sildenafil通过NO/cGMP通路舒张海绵体血管及平滑肌 ,应用于阳痿治疗取得了较好的临床效果。该文简要综述选择性PDEs抑制剂近年研究进展。     

磷酸二酯酶:从伟哥到抗阿尔茨海默病药物

磷酸二酯酶(PDE)是一个催化第二信使c AMP和/或c GMP水解的超级酶家族。它包括11个家族(PDE1～PDE11),对调节细胞内cAMP和cGMP水平发挥关键作用。PDE研究半个世纪以来,其靶位功能越发明显并受到重视。尤其是靶位PDE5的伟哥(Viagra,sildenafil;PDE5抑制剂)研制成功,使PDE研究成为国际药物研发的一大热点。PDE4抑制剂罗氟司特(roflumilast,Daxas~?)和apremilast(Otezla~?)分别成功用于治疗慢性阻塞性肺疾患(COPD)和银屑病及银屑病性关节炎,再次证明PDE作为药物靶标的重要研究价值和临床应用前景。阿尔茨海默病(AD)是一种慢性进行性神经退行性疾病,以记忆和认知能力的进行性减退为主要临床特征。研究表明,PDE2,PDE4,PDE5,PDE7,PDE9和PDE11都不同程度地参与AD学习记忆和认知的调节,其中尤以PDE4作用明显而广泛。PDE4有4种亚型(PDE4A～D),由不同基因编码。PDE4D研究相对较多。基因敲除或敲减PDE4D可改善AD小鼠的学习记忆障碍及抑郁等行为;对PDE4D有选择性抑制作用的化合物也有类似作用,提示PDE4D可能是治疗AD的重要靶标。然而,PDE4D也参与中枢性呕吐作用的调节。最新研究表明,通过别构抑制PDE4D可以达到既对抗AD小鼠的记忆下降,又不至于产生呕吐等副反应。这可能是抗AD药物研究的一个重要方向。     

磷酸二酯酶7:一个新的抗炎免疫药物靶点研究进展

磷酸二酯酶(phosphod iesterases,PDEs)作为体内特异性水解第二信使cAMP和cGMP的唯一蛋白酶家族,参与多种生理病理过程。研究表明PDE7是cAMP特异性的,分为PDE7A、PDE7B两个亚型,主要分布在免疫和炎症细胞中。PDE7作为一个新的潜在抗炎免疫药物靶点,其选择性抑制剂有可能用于治疗慢性阻塞性肺疾病(COPD)、类风湿性关节炎、阿尔采末病(AD)等与免疫炎症密切相关的疾病。     

Overview: Diabetes: New Chemical Entities

There has been an increasing interest in the development of phosphodiesterase (PDE) inhibitors for the treatment of cognitive dysfunctions. In this editorial, the mechanism of action of PDEs is briefly described, while the effects of different PDE inhibitors in preclinical models are reviewed. Based on the expression of PDE mRNA in the human brain, it is suggested that PDE1 and PDE10 inhibitors are strong candidates for the development of cognition enhancers. However, the complex nature of the expression of PDEs in the brain warrants further research into the role of PDEs in the signaling pathways in brain circuits. The development of PDE inhibitors, which are selective for PDE splicing isoforms, may be promising for future drug development.     

新的磷酸二酯酶及其功能

磷酸二酯酶(PDEs)基因家族已扩大到11个。新的PDE酶包括PDE7B，PDE8，PDE9A，PDEl0A，PDEllA。新发现的PDEs在调节阴茎勃起功能、胰岛素分泌、T细胞活化和感染、生长和发育中起重要作用。     

Therapeutic potential of cyclic nucleotide phosphodiesterase inhibitors in heart failure

There are several reasons to believe that agents that augment cAMP-mediated signalling in cardiac myocytes should have beneficial effects in patients with heart failure. However, clinical trials of first-generation cyclic nucleotide phosphodiesterase (PDE3) inhibitors, which raise cAMP content by blocking its hydrolysis, have shown that chronic administration of these drugs affect survival adversely. The problem may be the non-selective activation of a broad spectrum of cAMP-regulated cellular responses these agents elicit. More selective (or alternatively selective) cyclic nucleotide PDE inhibitors might improve results by evoking a more restricted set of cellular responses.     

Therapeutic potential of cyclic nucleotide phosphodiesterase inhibitors in heart failure

There are several reasons to believe that agents that augment cAMP-mediated signalling in cardiac myocytes should have beneficial effects in patients with heart failure. However, clinical trials of first-generation cyclic nucleotide phosphodiesterase (PDE3) inhibitors, which raise cAMP content by blocking its hydrolysis, have shown that chronic administration of these drugs affect survival adversely. The problem may be the non-selective activation of a broad spectrum of cAMP-regulated cellular responses these agents elicit. More selective (or alternatively selective) cyclic nucleotide PDE inhibitors might improve results by evoking a more restricted set of cellular responses.     

Selective inhibition of purified human phosphodiesterase 4A expressed in yeast cell GL62 by ciclamilast, piclamilast, and rolipram

AIM: To improve the specific activity of human phosphodiesterase 4A (PDE4A) expressed in yeast cell GL62 and investigate the effects of selective phosphodiesterase 4 (PDE4) inhibitors (ciclamilast, piclamilast, and rolipram), selective phosphodiesterase 5 (PDE5) inhibitor zaprinast, and cyclooxygenase (COX) inhibitors (aspirin, indomethacin) on human PDE4A activity expressed in yeast cell GL62. METHODS: Human PDE4A was expressed in yeast cell GL62 after CuSO4 induction and the specific activity of human PDE4A was improved by ammonium sulfate fractionation, DEAE Sephadex A-50 chromatography, and Sephadex G-100 chromatography. The activity of PDE4A was measured by high performance liquid chromatography (HPLC). RESULTS: Induced PDE4A activity expressed in crude yeast cell GL62 supernatant and pellet was (340±21) nmol·g-1·min-1 and (250±25) nmol·g-1·min-1 respectively. The specific activity of recombinant PDE4A in supernatant was improved 6.4 fold. Ciclamilast, piclamilast, and rolipram could inhibit P     

Hoe 694, a new Na+/H+ exchange inhibitor and its effects in cardiac ischaemia.

1. We have investigated the role of cyclic nucleotide phosphodiesterase IV (PDE IV) in the relaxation of human bronchus and guinea-pig trachea in vitro and in guinea-pigs in vivo. 2. Functional studies showed that the selective PDE IV inhibitors, rolipram and denbufylline, relaxed human and guinea-pig preparations in vitro. 3. Two clinically used xanthine non-selective PDE inhibitors, theophylline and pentoxifylline, were also effective in these preparations, but were much less potent than the selective agents used. 4. The rank order of potency for the four PDE inhibitors in both species was similar. 5. Biochemical studies indicated that PDE IV was the major PDE isoform present in the human bronchial tissue. PDEs I, II and V were also identified. 6. Theophylline and pentoxifylline were, as expected, non-selective inhibitors of the human enzymes, but there was a good correlation between PDE IV inhibitory and bronchorelaxation potencies, suggesting that PDE IV inhibition is important for the clinical bronchodilator activities of the two xanthine compounds. 7. We have confirmed the ability of selective PDE IV inhibitors to cause bronchodilatation in guinea-pigs in vivo. 8. We conclude that our study has provided further evidence that selective PDE IV inhibitors could act as bronchodilators in the clinic.     

磷酸二酯酶3抑制剂的功能和临床应用

磷酸二酯酶3（PDE3）是cAMP的水解酶,参与人体许多生理活动的调节。磷酸二酯酶3抑制剂升高细胞内cAMP水平,具有强心、血管舒张、抗血小板凝聚、抗增殖等作用,在心力衰竭和间歇性跛行等症的治疗中具有临床价值。     

Comparison of cyclic nucleotide phosphodiesterase isoenzymes in rat and rabbit ventricular myocardium: positive inotropic and phosphodiesterase inhibitory effects of Org 30029, milrinone and rolipram

Summary The species dependent variation in the cardiotonic activity of selective cyclic nucleotide phosphodiesterase (PDE) isoenzyme inhibitors was examined by comparing the inotropic and PDE inhibitory effects of Org 30029 (N-hydroxy-5,6-dimethoxy-benzo[b]thiophene-2-carboximidamide HCI), 3-isobutyl-l-methylxanthine (IBMX), milrinone and rolipram in rat and rabbit ventricular myocardium. The relative activities of PDE isoenzymes in rat and rabbit cardiac ventricle were also examined to assess the role of the different PDE subtypes in modulating contractile force in the two species. In rabbit papillary muscles, IBMX, Org 30029 and milrinone increased contractile force whilst rolipram was inactive. The rank order of potency of the active compounds was Org 30029 > IBMX > milrinone. Only Org 30029 and IBMX produced significant positive inotropic responses in rat papillary muscles, milrinone and rolipram being inactive. However, large positive inotropic responses were obtained in rat papillary muscles when milrinone and rolipram were tested in combination. In rabbit papillary muscles, the positive inotropic action of milrinone was markedly potentiated by rolipram. Four main types of PDE (I, II, III, IV) isoenzymes were resolved, by DEAE-sepharose or Mono-Q ion-exchange chromatography, from both rat and rabbit cardiac ventricular tissue. In rabbit, Ca²⁺/calmodulin dependent PDE (PDE I) and cyclic GMP inhibited PDE (PDE III) were the dominant cAMP activities. In contrast, cyclic GMP stimulated PDE (PDE II), PDE III and cGMP insensitive PDE (PDE IV) represented the main cAMP activities in rat cardiac ventricle. The inhibitory effects of Org 30029, IBMX, milrinone and rolipram on PDE isoenzymes from rat and rabbit cardiac ventricle were essentially similar. Milrinone and rolipram produced selective inhibition of PDE III and PDE IV, respectively. Org 30029 selectively inhibited PDE III and PDE IV whilst IBMX was non-selective and inhibited all PDE isoenzymes. In conclusion, the results show that species-dependent differences in the inotropic action of PDE isoenzyme selective inhibitors may be related to differences in the relative cAMP activity levels of PDE isoenzymes. It seems that in order to induce positive inotropism it is necessary to inhibit a sufficient proportion of low Km cAMP PDEs (such as dual inhibition of PDE III and PDE IV) in a relevant intracellular locale. Send offprint requests to M. Shahid at the above address     

Cyclic AMP-mediated regulation of vascular smooth muscle cell cyclic AMP phosphodiesterase activity

1. Rat cultured aortic vascular smooth muscle cells (VSMC) express both cyclic GMP-inhibited cyclic AMP phosphodiesterase (PDE3) and Ro 20-1724-inhibited cyclic AMP phosphodiesterase (PDE4) activities. By utilizing either cilostamide, a PDE3-selective inhibitor, or Ro 20-1724, a PDE4-selective inhibitor, PDE3 and PDE4 activities were shown to account for 15% and 55% of total VSMC cyclic AMP phosphodiesterase (PDE) activity.
2. Treatment of VSMC with either forskolin or 8-bromo-cyclic AMP caused significant concentration- and time-dependent increases in total cellular cyclic AMP PDE activity. Using cilostamide or Ro 20-1724, we demonstrated that both PDE3 and PDE4 activities were increased following forskolin or 8-bromo-cyclic AMP treatment, with a relatively larger effect observed on PDE3 activity. The increase in cyclic AMP PDE activity induced by forskolin or 8-bromo-cyclic AMP was inhibited by actinomycin D or cycloheximide, demonstrating that new mRNA synthesis and protein synthesis were required. An analogue of forskolin which does not activate adenylyl cyclase (1,9-dideoxyforskolin) or an analogue of cyclic GMP (8-bromo-cyclic GMP) did not affect total cyclic AMP PDE activity.
3. Incubation of VSMC with 8-bromo-cyclic AMP for 16 h caused a marked rightward shift in the concentration-response curves for both isoprenaline- and forskolin-mediated activation of adenylyl cyclase. A role for up-regulated cyclic AMP PDE activity in this reduced potency is supported by our observation that cyclic AMP PDE inhibitors (IBMX, cilostamide or Ro 20-1724) partially normalized the effects of isoprenaline or forskolin in treated cells to those in untreated cells.
4. We conclude that VSMC cyclic AMP PDE activity is increased following long-term elevation of cyclic AMP and that increases in PDE3 and PDE4 activities account for more than 70% of this effect. Furthermore, we conclude that increases in cyclic AMP PDE activity contribute to the reduced potency of isoprenaline or forskolin in treated VSMC. These results have implications for long-term use of cyclic AMP PDE inhibitors as therapeutic agents.