毒蕈碱型M1受体的同源模建和分子对接

采用同源模建方法对M1受体的三维结构进行了模拟, 将得到的模型分别与M受体完全激动剂乙酰胆碱和M1受体选择性激动剂占诺美林进行分子对接, 形成非特异性激动和特异性激动的受体-配体复合物. 用分子动力学模拟方法分别将未与小分子对接的M1受体、M1受体-乙酰胆碱复合物、M1受体-占诺美林复合物置于磷脂双膜中模拟10 ns. 将模拟后的蛋白质结构与包含活性分子的测试库对接并将结果打分, 以top5%富集因子(EF)作为评价依据, 用占诺美林优化后的M1受体模型的EF为8.0, 用乙酰胆碱优化后M1受体模型的EF为6.5, 非复合物的EF为1.5. 说明M1受体选择性激动剂复合物进行分子动力学模拟后得到的三维结构模型比较合理, 可以作为化合物虚拟筛选的模型对新化合物进行虚拟筛选, 为找到新的选择性M1受体激动剂奠定了基础.     

毒蕈碱型M1受体的同源模建和分子对接

采用同源模建方法对M1受体的三维结构进行了模拟,将得到的模型分别与M受体完全激动剂乙酰胆碱和M1受体选择性激动剂占诺美林进行分子对接,形成非特异性激动和特异性激动的受体-配体复合物.用分子动力学模拟方法分别将未与小分子对接的M1受体、M1受体-乙酰且H碱复合物、M1受体-占诺美林复合物置于磷脂双膜中模拟10 ns.将模拟后的蛋白质结构与包含活性分子的测试库对接并将结果打分,以top5%富集因子(EF)作为评价依据,用占诺美林优化后的M1受体模型的EF为8.0,用乙酰胆碱优化后M1受体模型的EF为6.5,非复合物的EF为1.5.说明M1受体选择性激动剂复合物进行分子动力学模拟后得到的三维结构模型比较合理,可以作为化合物虚拟筛选的模型对新化合物进行虚拟筛选,为找到新的选择性M1受体激动剂奠定了基础.     

新型减肥药利莫纳班的离子阱质谱和电子轰击质谱研究

新型减肥药利莫纳班(rimonabant)是一种选择性CB1受体拮抗剂,服后不易反弹.利莫纳班具有减轻体重和戒除烟瘾的功效,并能降低胆固醇、预防肥胖人群患上心脏病和糖尿病等.     

P2Y12受体拮抗剂定量构效关系的研究

P2Y12受体拮抗剂是一类重要的抗血小板药物,研究分子活性与其结构参数的关系,对于合成新的P2Y12受体拮抗剂具有一定指导作用.选用178个结构多样的P2Y12受体拮抗剂分子作为数据集,随机选取了143个P2Y12受体拮抗剂作为训练集,剩余分子作为检验集.采用多元线性回归(MLR)方法和主成分回归分析(PCA)方法对每个分子的636个分子参数进行线性回归分析.MLR所建模型的结果为:训练集R2=0.800,检验集R2=0.834;PCA模型结果为:训练集R2=0.545,检验集R2=0.665.相比之下MLR法所建模型具有良好的预测性和可靠性.通过模型分析,确定了影响分子活性的关键因素.以上模型对筛选和合成新型高效P2Y12受体拮抗剂提供了一定理论指导.     

盐酸阿扎司琼合成工艺研究

盐酸阿扎司琼(Azasetron hydrochloride)是一种高选择性,副作用低的5-HT_3受体拮抗剂。本研究通过文献调研发现目前已报道的合成路线存在着工艺复杂,污染大等问题。针对这些问题,本研究报道了一条更加简便,环保,有工业化潜力的路线,通过五步反应得到目标产物,其结构经~1H-NMR、~(13)C-NMR及MS确认,总收率67.5%。     

N-甲基-1-甲硫基-2-硝基乙烯胺的合成新工艺研究

雷尼替丁(Ranitidine)为一种选择性的H2受体拮抗剂,能有效抑制组胺、五肽胃泌素及食物刺激后引起的胃酸分泌,降低胃酸和胃酶的活性,且对胃泌素及性激素的分泌无影响。主要用于治疗十二指肠溃疡、良性胃溃疡、术后溃疡、反流性食管炎及卓-艾综合症等[1]。N-甲基-1-甲硫基-2-硝基     

4-苄基哌啶类拮抗剂选择性识别hCCR3的分子模拟

以牛视网膜紫质X射线衍射晶体结构为模板, 参考定位突变实验数据, 采用配体支持同源模建(Ligand-supported homology modeling)方法构建了拮抗剂键合(Antagonist-bound)的人类趋化因子受体hCCR3和hCCR1的三维结构模型. 将一系列1,4-二取代哌啶类拮抗剂分别对接进优化后的hCCR3和hCCR1模型中, 以配体在hCCR3中的结合自由能理论值对-lgIC₅₀值进行线性回归, 确定性系数r²为0.94. 分析对接结果发现, 配体主要通过疏水芳香作用与hCCR3结合, 而4-苄基哌啶类拮抗剂对hCCR3产生选择性的主要原因在于配体的哌啶环与hCCR3中Tyr255(TM7)的苯酚侧链产生面对面的范德华作用, 而且hCCR3中处于结合口袋的EL2区的疏水性也为拮抗剂对hCCR3的选择性做出了贡献.     

新型α1受体拮抗剂先导化合物的寻找(I): 5-氯-2-(4-(芳氧烷基)哌嗪-1-基)苯并噁唑类化合物的设计、合成及生物活性研究

为寻找用于治疗良性前列腺增生的新型α1受体拮抗剂, 以本研究组发现的2-[(4-(2-(2-氯苯氧基)乙基)哌嗪-1-基)甲基]-5-甲基苯并噁唑(wb5c)为先导化合物, 结合已构建的α1-AR拮抗剂药效团模型, 通过骨架改造, 设计出以苯并噁唑-2-基哌嗪为母核的目标物, 然后以5-氯-2-氨基酚和取代苯酚为原料, 经缩合、卤代、氨化、Williamson醚合成、取代等反应共合成11个新目标化合物, 结构经ESI-MS, 1H NMR, IR及HRMS确证. 初步药理活性实验表明, 目标物具有中等强度α1受体拮抗活性, 符合我们提出的三元素药效团模型. 5-氯-2-[4-(芳氧烷基)哌嗪-1-基]类化合物是一类新的具有潜在开发价值的α1受体拮抗剂.     

改性HY型分子筛对废塑料油轻质化的影响

以HY分子筛和硝酸盐[M(NO3)2,M=Ni,Zr,Ca和Ce]为原料,通过浸渍法制得改性HY型分子筛(M/HY)催化剂,其结构和性能经XRD,比表面积,IR和SEM表征。考察了M/HY催化重质油轻质化的效果,结果表明,稀土金属的添加使重质油转化率得到了提高,平均转化率均在40%以上。从总选择性以及类汽油选择性来看,其中Ni/HY活性较好,类汽油选择性平均值为53.98%,最高达72.56%,选择性均优于HY分子筛(21.32%)。     

距离比较法构建M1受体激动剂药效团模型

在M1受体三维结构未知的情况下,利用距离比较法(DISCO)对24个具有Mi受体激动活性的化合物进行了研究,构建了Mi受体激动剂可能的药效团模型,为设计新M1受体激动剂提供了参考,并以此为提问结构在ACD数据库和中草药数据系统(TCMDB)中进行搜索,得到一系列结构新颖并可能具有Mi激动活性的化合物.     

Real time differentiation of G-protein coupled receptor (GPCR) agonist and antagonist by two photon fluorescence laser microscopy

Receptor-based signaling mechanisms are the primary source of cellular regulation. The superfamily of G protein-coupled receptors (GPCR) is the largest and most ubiquitous of the receptor-mediated processes. Desensitization of G-protein-coupled receptors is a fundamental mechanism regulating the cellular response to agonists. We have recently studied the agonist and antagonist of the human melanocortin receptors (hMC1, hMC3, hMC4, and hMC5 receptors), the human delta opioid receptor, and the human gluacagon receptor with the help of synthetic fluorescent labeled ligands and fluorescent protein-labeled beta-arrestin-receptors that shed new insight on cellular signaling and rapid screening of drugs in real time. It was demonstrated that stimulation of these receptors by the cognate agonist triggers the rapid internalization of ligand-receptor complexes, while the interaction of the receptor with antagonists does not follow this pathway. Furthermore, receptor internalization is dependent upon beta-arrestin, which has been shown to be responsible for the rapid desensitization of cAMP-signaling processes.     

Discovery of 2-aminothiazole-4-carboxamides, a novel class of muscarinic M(3) selective antagonists, through solution-phase parallel synthesis

Synthesis and structure-activity relationship of a new class of muscarinic M(3) selective antagonists were described. In the course of searching for a muscarinic M(3) antagonist with a structure distinct from those of the 2-(4,4-difluorocyclopentyl)-2-phenylacetamide derivatives, we identified a thiazole-4-carboxamide derivative (1) as a lead compound in our in-house chemical collection. Since this compound (1) showed relatively low binding affinity (K(i)=140 nM) for M(3) receptors in the human binding assays, we tried to improve its potency and selectivity for M(3) over M(1) and M(2) receptors by derivatization of 1 through a combinatorial approach. A solution-phase parallel synthesis effectively contributed to the optimization of each segment of 1. Thus, we have identified a cyclooctenylmethyl derivative (3e) and a cyclononenylmethyl derivative (3f) as representative M(3) selective antagonists in this class.     

Allosteric antagonist binding sites in class B GPCRs: corticotropin receptor 1

The 41 amino acid neuropeptide, corticotropin-releasing factor (CRF) and its associated receptors CRF₁-R and CRF₂-R have been targeted for treating stress related disorders. Both CRF₁-R and CRF₂-R belong to the class B G-protein coupled receptors for which little information is known regarding the small molecule antagonist binding characteristics. However, it has been shown recently that different non-peptide allosteric ligands stabilize different receptor conformations for CRF₁-R and hence an understanding of the ligand induced receptor conformational changes is important in the pharmacology of ligand binding. In this study, we modeled the receptor and identified the binding sites of representative small molecule allosteric antagonists for CRF₁-R. The predicted binding sites of the investigated compounds are located within the transmembrane (TM) domain encompassing TM helices 3, 5 and 6. The docked compounds show strong interactions with H228 on TM3 and M305 on TM5 that have also been implicated in the binding by site directed mutation studies. H228 forms a hydrogen bond of varied strengths with all the antagonists in this study and this is in agreement with the decreased binding affinity of several compounds with H228F mutation. Also mutating M305 to Ile showed a sharp decrease in the calculated binding energy whereas the binding energy loss on M305 to Leu was less significant. These results are in qualitative agreement with the decrease in binding affinities observed experimentally. We further predicted the conformational changes in CRF₁-R induced by the allosteric antagonist NBI-27914. Movement of TM helices 3 and 5 are dominant and generates three degenerate conformational states two of which are separated by an energy barrier from the third, when bound to NBI-27914. Binding of NBI-27914 was predicted to improve the interaction of the ligand with M305 and also enhanced the aromatic stacking between the ligand and F232 on TM3. A virtual ligand screening of ~13,000 compounds seeded with ~350 CRF₁-R specific active antagonists performed on the NBI-27914 stabilized conformation of CRF₁-R yielded a 44% increase in enrichment compared to the initially modeled receptor conformation at a 10% cutoff. The NBI-27914 stabilized conformation also shows a high enrichment for high affinity antagonists compared to the weaker ones. Thus, the conformational changes induced by NBI-27914 improved the ligand screening efficiency of the CRF₁-R model and demonstrate a generalized application of the method in drug discovery.     

Internet resources in GPCR modelling1

G-Protein coupled receptors (GPCRs), one of the most important families of drug targets, belong to the super family of integral membrane proteins characterized by seven transmembrane helices. Because they are difficult to crystallize, the three dimensional structure of these receptors have not yet been determined by X-ray crystallography, except one. In the absence of a 3-D structure, in-silico approaches for solving the structure of this class of proteins are widely used and provide valuable information for structure based drug design. There are several web servers and computer programs available that automate the modelling process of GPCRs. Some of these include Modeller, Swiss-Model server, Homer, etc. Using these tools reliable homology models of human histamine H1 receptor (HRH1) and thrombin receptor (PAR-1) have been generated which explain the binding mode of the standard antagonists of these receptors and may be useful in designing their novel antagonists.     

Internet resources in GPCR modelling

G-Protein coupled receptors (GPCRs), one of the most important families of drug targets, belong to the super family of integral membrane proteins characterized by seven transmembrane helices. Because they are difficult to crystallize, the three dimensional structure of these receptors have not yet been determined by X-ray crystallography, except one. In the absence of a 3-D structure, in-silico approaches for solving the structure of this class of proteins are widely used and provide valuable information for structure based drug design. There are several web servers and computer programs available that automate the modelling process of GPCRs. Some of these include Modeller, Swiss-Model server, Homer, etc. Using these tools reliable homology models of human histamine H1 receptor (HRH1) and thrombin receptor (PAR-1) have been generated which explain the binding mode of the standard antagonists of these receptors and may be useful in designing their novel antagonists.     

Neuroprotection with the Cannabidiol Quinone Derivative VCE-004.8 (EHP-101) against 6-Hydroxydopamine in Cell and Murine Models of Parkinson’s Disease

The 3-hydroxyquinone derivative of the non-psychotrophic phytocannabinoid cannabigerol, so-called VCE-003.2, and some other derivatives have been recently investigated for neuroprotective properties in experimental models of Parkinson’s disease (PD) in mice. The pharmacological effects in those models were related to the activity on the peroxisome proliferator-activated receptor-γ (PPAR-γ) and possibly other pathways. In the present study, we investigated VCE-004.8 (formulated as EHP-101 for oral administration), the 3-hydroxyquinone derivative of cannabidiol (CBD), with agonist activity at the cannabinoid receptor type-2 (CB₂) receptor in addition to its activity at the PPAR-γ receptor. Studies were conducted in both in vivo (lesioned-mice) and in vitro (SH-SY5Y cells) models using the classic parkinsonian neurotoxin 6-hydroxydopamine (6-OHDA). Our data confirmed that the treatment with VCE-004.8 partially reduced the loss of tyrosine hydroxylase (TH)-positive neurons measured in the substantia nigra of 6-OHDA-lesioned mice, in parallel with an almost complete reversal of the astroglial (GFAP) and microglial (CD68) reactivity occurring in this structure. Such neuroprotective effects attenuated the motor deficiencies shown by 6-OHDA-lesioned mice in the cylinder rearing test, but not in the pole test. Next, we explored the mechanism involved in the beneficial effect of VCE-004.8 in vivo, by analyzing cell survival in cultured SH-SY5Y cells exposed to 6-OHDA. We found an important cytoprotective effect of VCE-004.8 at a concentration of 10 µM, which was completely reversed by the addition of antagonists, T0070907 and SR144528, aimed at blocking PPAR-γ and CB₂ receptors, respectively. The treatment with T0070907 alone only caused a partial reversal, whereas SR144528 alone had no effect, indicating a major contribution of PPAR-γ receptors in the cytoprotective effect of VCE-004.8 at 10 µM. In summary, our data confirmed the neuroprotective potential of VCE-004.8 in 6-OHDA-lesioned mice, and in vitro studies confirmed a greater relevance for PPAR-γ receptors rather than CB₂ receptors in these effects.     

A reactivity pattern for discrimination of ER agonism and antagonism based on 3-D molecular attributes

Various models have been developed to predict the relative binding affinity (RBA) of chemicals to estrogen receptors (ER). These models can be used to prioritize chemicals for further tiered biological testing to assess the potential for endocrine disruption. One shortcoming of models predicting RBA has been the inability to distinguish potential receptor antagonism from agonism, and hence in vivo response. It has been suggested that steroid receptor antagonists are less compact than agonists; thus, ER binding of antagonists may prohibit proper alignment of receptor protein helices preventing subsequent transactivation. The current study tests the theory of chemical bulk as a defining parameter of antagonism by employing a 3-D structural approach for development of reactivity patterns for ER antagonists and agonists. Using a dataset of 23 potent ER ligands (16 agonists, 7 antagonists), molecular parameters previously found to be associated with ER binding affinity, namely global ( E HOMO ) and local (donor delocalizabilities and charges) electron donating ability of electronegative sites and steric distances between those sites, were found insufficient to discriminate ER antagonists from agonists. However, parameters related to molecular bulk, including solvent accessible surface and negatively charged Van der Waal's surface, provided reactivity patterns that were 100% successful in discriminating antagonists from agonists in the limited data set tested. The model also shows potential to discriminate pure antagonists from partial agonist/antagonist structures. Using this exploratory model it is possible to predict additional chemicals for their ability to bind but inactivate the ER, providing a further tool for hypothesis testing to elucidate chemical structural characteristics associated with estrogenicity and anti-estrogenicity.     

Ginkgolides and glycine receptors: a structure-activity relationship study

Ginkgolides from the Ginkgo biloba tree are diterpenes with a cage structure consisting of six five-membered rings and a unique tBu group. They exert a variety of biological properties. In addition to being antagonists of the platelet activating factor receptor (PAFR), it has recently been shown that native ginkgolides are potent and selective antagonists of the inhibitory glycine receptor. Forty new ginkgolide derivatives have been prepared in good to high yields on milligram scales and investigated for their antagonistic properties at homomeric alpha 1 glycine receptors, thus providing the first structure-activity relationship study of ginkgolides at glycine receptors. A high-throughput screening assay showed that native ginkgolide C was the most potent ligand, and that manipulation of any of the hydroxyl groups led to loss of activity at alpha 1 glycine receptors.     

Dual CCK-A and CCK-B receptor antagonists (II). Preparation and structure activity relationships of 5-alkyl-9-methyl-1,4-benzodiazepines and discovery of FR208419

In our continuing research for dual CCK-A and -B antagonists, according to our hypothesis that dual CCK-A and -B antagonists should be more efficacious than selective CCK-A antagonists for the treatment of pancreatitis, we have prepared various 5-alkyl-9-methyl-1,4-benzodiazepines. From the compounds prepared, 1-cyclohexyl-carbonylmethyl-5-ethyl-9-methyl-3- (m-tolylureido)-2-oxo-1,4-benzodiazepine, (40) was selected as a candidate for development due to its well-balanced high affinity for both receptors. The R-enantiomer of 40, (R)-40 (FR 208419), had 27-fold higher affinity for the CCK-A receptor and 8-fold more potent CCK-B receptor binding activity than (S)-40. The biological activity after p.o. administration of (R)-40, estimated from the ID50 value (0.23 mg/kg p.o.) obtained by preliminary evaluation by gastric emptying effects, is considered to be high enough for further development. This compound is now undergoing further biological evaluations with a view to clinical development.     

A reactivity pattern for discrimination of ER agonism and antagonism based on 3-D molecular attributes

Various models have been developed to predict the relative binding affinity (RBA) of chemicals to estrogen receptors (ER). These models can be used to prioritize chemicals for further tiered biological testing to assess the potential for endocrine disruption. One shortcoming of models predicting RBA has been the inability to distinguish potential receptor antagonism from agonism, and hence in vivo response. It has been suggested that steroid receptor antagonists are less compact than agonists; thus, ER binding of antagonists may prohibit proper alignment of receptor protein helices preventing subsequent transactivation. The current study tests the theory of chemical bulk as a defining parameter of antagonism by employing a 3-D structural approach for development of reactivity patterns for ER antagonists and agonists. Using a dataset of 23 potent ER ligands (16 agonists, 7 antagonists), molecular parameters previously found to be associated with ER binding affinity, namely global (E(HOMO)) and local (donor delocalizabilities and charges) electron donating ability of electronegative sites and steric distances between those sites, were found insufficient to discriminate ER antagonists from agonists. However, parameters related to molecular bulk, including solvent accessible surface and negatively charged Van der Waal's surface, provided reactivity patterns that were 100% successful in discriminating antagonists from agonists in the limited data set tested. The model also shows potential to discriminate pure antagonists from partial agonist/antagonist structures. Using this exploratory model it is possible to predict additional chemicals for their ability to bind but inactivate the ER, providing a further tool for hypothesis testing to elucidate chemical structural characteristics associated with estrogenicity and anti-estrogenicity.