基于药效团模型从中草药数据库中搜索gpIIb/IIIa受体抑制剂

选择20 个3,4-二氢-1(1H)-异喹啉酮类gpIIb/IIIa受体抑制剂作为训练集, 利用Catalyst软件包建立了gpIIb/IIIa受体抑制剂三维药效团模型. 探讨了药效团作用模式. 并通过建立的可靠性最佳的药效团模型(线性回归系数r=0.7715), 从中草药数据库中虚拟筛选了gpIIb/IIIa受体抑制剂, 通过实验活性测定得到了8个抑制ADP活化全血血小板聚集的IC50从40到100 μmol·L-1的化合物, 进一步证明了所建药效团模型的有效性.     

糖蛋白(GP)Ⅱb/Ⅲa拮抗剂的合成与活性

血小板凝聚最后的共同的一步是纤维蛋白原结合糖蛋白Ⅱb/Ⅲa受体,因此GPⅡ/Ⅲa受体拮抗剂应优于阻断其他单一途径的抗血小板药物.合成了13个化合物,其中4个化合物在体外活性上和模板化合物相当.     

黄酮体化合物抗肿瘤活性的量子化学研究

本文对黄酮类化合物抗肿瘤活性进行了量子化学研究。采用从头算方法计算了黄酮体化合物的电荷分布，并基于电荷分布提出了黄酮体化合物表现抗肿瘤活性时与受体作用的模型：A环与受体的负电荷中心结构，C环与受体的正电荷中心结合，其他部分通过氢键与受体发生作用，氢键在受体的作用中起到很大的作用。     

奥拉西坦衍生物的设计、合成及抗血小板聚集活性研究

本文采用拼合策略,设计、合成了7个新型奥拉西坦衍生物。其中,化合物4a～4f由奥拉西坦与苯丙烯酸片段拼合得到; 4g则由奥拉西坦、吲哚布芬拼合得到。采用Bron比浊法测定目标化合物对花生四烯酸及二磷酸腺苷诱导的血小板聚集的抑制活性。结果表明,该系列化合物具有一定的抗血小板聚集活性,其中化合物4f的抗血小板聚集活性与阳性对照吲哚布芬相当。     

基于药效团模型从中草药数据库中搜索gpⅡb/Ⅲa受体抑制剂

选择20个3,4-二氢-1(1H)-异喹啉酮类gpⅡb/Ⅲa受体抑制剂作为训练集,利用Catalyst软件包建立了gpⅡb/Ⅲa受体抑制剂三维药效团模型.探讨了药效团作用模式.并通过建立的可靠性最佳的药效团模型(线性回归系数r=0.7715),从中草药数据库中虚拟筛选了gpⅡb/Ⅲa受体抑制剂,通过实验活性测定得到了8个抑制ADP活化全血血小板聚集的IC50从40到100μmol·L-1的化合物,进一步证明了所建药效团模型的有效性.     

PPAR激动剂的定向设计、虚拟筛选及合成

过氧化物酶体增殖因子活化受体(PPAR)是核受体超家族的一员.基于受体结构的药物分子设计与组合化学策略相结合,构建了过氧化物酶体增殖因子活化受体(PPAR)激动剂的虚拟化合物库.将已知小分子配体(GW409544)与PPAR晶体复合物进行剥离,得到受体的活性构象,并利用此活性受体分子与虚拟库中小分子进行对接和虚拟筛选,得到理论上结合较强的化合物,并对这些化合物进行合成,共合成9个新化合物.活性筛选结果显示化合物对PPAR具有一定的亲和力,其中有三个化合物显示出对PPARα,PPARγ的双重激动作用,从而指导新活性化合物的设计和合成.     

同系列电子给体与同系列电受体电荷转移络合作用的研究

用电子吸收光谱法, 研究了五个电子受体系列和三个电子给体系列以及非同系列的给、受体共48个化合物间的弱电荷转移络合作用。发现所研究的同系列给体与同一受体作用; 或同系列受体与同一给体作用; 或同系列给体与同系列受体作用, 一般存在着明显的CT络合与表观不络合的现象。通常情况下, 同系序数大的化合物呈现表观不络合;有时, 同系序数大和小的化合物, 即同系物的两头均呈现表观不络合现象, 对此种现象用给、受体间前线分子轨道能级关系进行了讨论。     

同系列电子给体与同系列电受体电荷转移络合作用的研究

用电子吸收光谱法, 研究了五个电子受体系列和三个电子给体系列以及非同系列的给、受体共48个化合物间的弱电荷转移络合作用。发现所研究的同系列给体与同一受体作用; 或同系列受体与同一给体作用; 或同系列给体与同系列受体作用, 一般存在着明显的CT络合与表观不络合的现象。通常情况下, 同系序数大的化合物呈现表观不络合;有时, 同系序数大和小的化合物, 即同系物的两头均呈现表观不络合现象, 对此种现象用给、受体间前线分子轨道能级关系进行了讨论。     

新型吡啶[2',1': 5,1]吡唑[4, 3-d]嘧啶-4-酮类化合物的合成及其对PDE5酶的抑制活性研究

设计、合成出了新型吡啶并吡唑并嘧啶酮类化合物。目标化合物的生物活性评价结果显示，该类化合物对血小板中的PDE5酶具有较强的拟制活性，但略弱于西地那非。     

酪氨酸激酶抑制剂的柔性原子受体模型方法研究

用柔性原子受体模型方法对一系列嘧啶类衍生物酪氨酸激酶抑制剂进行了3D－ QSAR研究，建立了相关性很好的模型，这些模型对测试集中化合物活性的预测结果 表明其具有较强的预测能力。柔性原子受体模型方法还给出了虚拟的受体模型，表 明了受体和配体之间可能的相互作用，包括两个氢键相互作用、一个疏水作用和一 个硫－芳香相互作用，这与Novartis的药效团模型非常一致。     

Organization of the glycoprotein (GP) IIb/IIIa heterodimer on resting human platelets studied by flow cytometric energy transfer.

Glycoprotein IIb/IIIa is a heterodimer of glycoproteins IIb and IIIa which serves as the inducible receptor for fibrinogen and other adhesive proteins at the surface of platelets. Although a model of the quaternary structure of the GPIIb/IIIa molecule has been constructed in solution by Calvete et al. [Biochem. J. 282 (1992) 523], a corresponding model at the surface of intact platelets is still missing. In the present work conformation and lateral distribution of the GPIIb/IIIa heterodimer were studied at a nanometer resolution on the surface of resting human platelets under physiological conditions. The experiments were based on dual wavelength flow cytometric detection of fluorescence resonance energy transfer and application of a panel of monoclonal antibodies raised against well described binding sites. Monodisperse distribution of the GPIIb/IIIa heterodimer has been observed and a detailed three-dimensional proximity map of antibody binding sites was constructed on the platelet membrane, under physiological conditions, for the first time. Our data support the view that the GPIIb subunit is in a bent conformation. A detailed analysis of the K(d)-values and the number of binding sites for a set of monoclonal antibodies was also carried out giving supplementary data for the topology of the binding sites. Our results provide a refinement of the membrane-topology of the GPIIb/IIIa heterodimer.     

Novel non-peptide GPIIb/IIIa antagonists: synthesis and biological activities of 2-[4-[2-(4-amidinobenzoylamino)-2-(substituted)acetyl]-3-(2-methoxy-2-oxoethyl)-2-oxopiperazinyl] acetic acids

To improve the in vitro and in vivo potency of our first low molecular weight GPIIb/IIIa antagonist 1 (TAK-029), a series of 2-[4-[2-(4-amidinobenzoylamino)-2-(substituted)acetyl]-3-(2-methoxy-2-oxoethyl)-2-oxopiper-azinyllacetic acids were synthesized through modification of the glycine moiety of 1 and evaluated for their ability to inhibit in vitro adenosine 5'-diphosphate (ADP)-induced platelet aggregation of guinea pig platelet rich plasma (PRP). Among the compounds examined, the (3S,2S)-4-methoxyphenylalanine derivative 4h showed the most potent antagonistic activity with an IC50 value of 13 nM. Dose-dependent inhibition of ex vivo platelet aggregation was achieved with oral administration of 4h (0.3-1.0 mg/kg) to guinea pigs. Complete inhibition was observed for up to 8 h, and 43% inhibition could still be observed 24 h after oral administration of 1.0 mg/kg. The long-lasting antiplatelet effect of 4h suggests that 4h would be suitable for once-a-day dosing. Structure-activity relationships (SAR) were examined in the series of the phenylalanine derivatives. An increase in the electron density around the 4-position of the phenyl ring of the phenylalanine moiety led to an increase in the antiplatelet activity, suggesting the existence of a hydrophobic and electrostatic interaction site in addition to the ionic binding sites in the GPIIb/IIIa.     

Enzyme‐Mediated Site‐Specific Bioconjugation of Metal Complexes to Proteins: Sortase‐Mediated Coupling of Copper‐64 to a Single‐Chain Antibody

The enzyme‐mediated site‐specific bioconjugation of a radioactive metal complex to a single‐chain antibody using the transpeptidase sortase A is reported. Cage amine sarcophagine ligands that were designed to function as substrates for the sortase A mediated bioconjugation to antibodies were synthesized and enzymatically conjugated to a single‐chain variable fragment. The antibody fragment scFv_anti‐LIBS targets ligand‐induced binding sites (LIBS) on the glycoprotein receptor GPIIb/IIIa, which is present on activated platelets. The immunoconjugates were radiolabeled with the positron‐emitting isotope ⁶⁴Cu. The new radiolabeled conjugates were shown to bind selectively to activated platelets. The diagnostic potential of the most promising conjugate was demonstrated in an in vivo model of carotid artery thrombosis using positron emission tomography. This approach gives homogeneous products through site‐specific enzyme‐mediated conjugation and should be broadly applicable to other metal complexes and proteins.     

Orally active GPIIb/IIIa antagonists: synthesis and biological activities of masked amidines as prodrugs of 2-[(3S)-4

To improve the in vivo potency of the potent GPIIb/IIIa antagonist 2-[(3S)-4-[(2S)-2-(4-amidinobenzoylamino)-3-(4-methoxyphenyl)propanoyl]-3-(2-methoxy-2-oxoethyl)-2-oxopiperazinyljacetic acid (4), the amidino group was converted to an oxadiazole ring, thiadiazole ring or substituted amidoxime group. These groups were expected to be metabolized to an amidino group in vivo. The compounds synthesized were evaluated for their potency to inhibit the ex vivo adenosine 5'-diphosphate (ADP)-induced aggregation of guinea pig platelets. Among the compounds examined, the methoxycarbonyloxyamidine 8a exhibited the most potent ex vivo inhibitory activity with a fast onset and prolonged duration of action after oral administration.     

Targeted Antithrombotic Protein Micelles

Activated platelets provide a promising target for imaging inflammatory and thrombotic events along with site‐specific delivery of a variety of therapeutic agents. Multifunctional protein micelles bearing targeting and therapeutic proteins were now obtained by one‐pot transpeptidation using an evolved sortase A. Conjugation to the corona of a single‐chain antibody (scFv), which binds to the ligand‐induced binding site (LIBS) of activated GPIIb/IIIa receptors, enabled the efficient detection of thrombi. The inhibition of thrombus formation was subsequently accomplished by incorporating the catalytically active domain of thrombomodulin (TM) onto the micelle corona for the local generation of activated protein C, which inhibits the formation of thrombin. An effective strategy has been developed for the preparation of protein micelles that can be targeted to sites of activated platelets with broad potential for treatment of acute thrombotic events.     

Preparation and pharmacological evaluation of novel glycoprotein (Gp) IIb/IIIa antagonists. 2. Condensed heterocyclic derivatives

A novel series of platelet receptor glycoprotein (Gp) IIb/IIIa antagonists with condensed heterocycles as their basic core was synthesized. In an in vitro assay, trans-4-(5-amidinobenzofuran-2-carboxamido)cyclohexyloxyacetic+ ++ acid 17e and trans-3-[4-(5-amidinobenzofuran-2- carboxamido)cyclohexyl]propionic acid 17f produced marked inhibitions with IC50 values of 0.018 and 0.006 microM, respectively in a human platelet adenosin-5'-diphospate (ADP)-induced aggregation assay; they also exhibited a wide spectrum of inhibition toward major aggregation agonists (ADP, collagen, thrombin, PMA (tumor promoter) and arachidonic acid). These compounds were > 2-3 orders of magnitude more effective in inhibiting platelet aggregation than human umbilical vein endothelial cell (HUVEC) binding. The oral administration of 10 mg/kg of either 17e and 17f to guinea pig, resulted in a 60% inhibition of ex vivo platelet aggregation after 5 h. Oral administration of ethyl trans-4-(5-amidinoben-zofuran-2- carboxamido)cyclohexyloxyacetate 18e (10 mg/kg) resulted in 80% inhibition of platelet aggregation in dogs for 6 h after oral administration with a return to baseline by 24 h. Ethyl trans-3-[4-(5-amidinobenzofuran-2-carboxamido)cyclohexyl]propionat e 18f (AR0598) produced 80% inhibition for 5 h after oral administration. Prodrug 18e showed a good profile in dogs with a long duration of action. 18e (AR0510) was selected as suitable clinical candidate for development as an orally active antithrombotic agent.     

Selectivity of Molecular Recognition Displayed by Monoclonal Antibodies as Compared to Receptors – a New Approach to Screen Combinatorial Libraries

Photolabeled monoclonal antibodies generated against a potent antagonist of the glycoprotein receptor GPIIb‐IIIa have been used to demonstrate that antibodies can be employed to replace receptors for on‐bead screening of combinatorial libraries.     

<Superscript>99m</Superscript>Tc-roxifiban: a potential molecular imaging agent for the detection and localization of acute venous thrombosis

^99mTc-roxifiban was obtained in a high radiochemical yield (98.4%) by complexing ~750 MBq ^99mTc with 2.5 mg roxifiban in the presence of 150 µg SnCl₂·2H₂O. Factors affecting the labelling yield were investigated and optimized. The complex was lipophilic and stable in saline and serum for more than 8 h. The complex structure prediction and molecular docking to its target activated GPIIb/IIIa receptor were performed. The tracer in vitro binding to activated platelets was high (27–32%). In vivo evaluation was performed through clearance, biodistribution and imaging studies in rats. All results supported the usefulness of the tracer as thrombus imaging agent.     

CuI-catalyzed coupling reaction of beta-amino acids or esters with aryl halides at temperature lower than that employed in the normal Ullmann reaction. Facile synthesis of SB-214857

[reaction: see text] The CuI-catalyzed coupling reaction of aryl halides with beta-amino acids or beta-amino esters is completed at 100 degrees C in 48 h, which indicates that the structure of the beta-amino acid has an accelerating effect for the Ullmann-type aryl amination reaction. This coupling reaction can be used to prepare enantiopure N-aryl beta-amino acids. An efficient synthetic route to SB214857, a potent GPIIb/IIIa receptor antagonist, is developed using this method.