Development of inhibitors of the aspartyl protease renin for the treatment of hypertension

Renin is the rate-limiting enzyme in the renin-angiotensin-aldosterone system (RAS) which controls blood pressure and volume. The biological function of renin is to cleave the N-terminus of angiotensinogen releasing the decapeptide, angiotensin I (ANGI). Subsequently, angiotensin I is further processed by the angiotensin converting enzyme (ACE) to produce angiotensin II (ANGII). The RAS cascade is a major target for the clinical management of hypertension. Current clinical treatments include angiotensin converting enzyme inhibitors (ACEi) and ANGII receptor blockers (ARBs). As the rate-limiting enzyme in ANGII production, renin inhibitors have been pursued as an additional class of anti-hypertensives. Clinical studies conducted with renin inhibitors have shown them to be as effective as ACE inhibitors in lowering blood pressure. Most importantly, inhibitors of renin may have a number of potential advantages over ACEi and ARBs. Renin is specific for angiotensinogen and will not carry the ancillary pharmacology associated with ACEi or ARBs. To date, no renin inhibitors have made it to market. The development of these inhibitors has been hindered by poor bioavailability and complex synthesis. However, despite the pharmacokinetic challenges of designing renin inhibitors, the enzyme remains a promising target for the development of novel treatments for hypertension. This review will consist of an overview of renin biology, the pharmacology of renin and RAS and focus in on renin as a target for blood pressure regulation. We also cover the evaluation of renin inhibitors in animal models and clinical studies. Presently a number of new generation inhibitors of renin are in development with at least one in the clinic and these will be discussed. Finally we will discuss what might distinguish renin inhibitors from current therapeutic options and discuss other therapeutic indications renin inhibitors might have.     

Recent research and development of DYRK1A inhibitors

Dual specificity tyrosine phosphorylation regulated kinase 1 A(DYRK1 A) is an evolutionarily conserved protein kinase belonging to the CMGC kinase family, which is closely related to Down syndrome(DS)and Alzheimer’s disease(AD). In recent years, not only the treatment of diabetes, but also the treatment of cancer gradually focuses on targeting DYRK1 A. Therefore, a series of DYRK1 A inhibitors have been developed to treat relevant diseases and clarify their treatment mechanism furtherly. DYRK1 A...     

Mixing of peptides and electrophilic traps gives rise to potent, broad-spectrum proteasome inhibitors

The synthesis and evaluation of hybrid proteasome inhibitors that contain structural elements of the known inhibitors bortezomib, epoxomicin and peptide vinyl sulfones is described. From the panel of 15 inhibitors some structure activity relationships can be deduced with regard to inhibitory activity in relation to peptide recognition element, inhibitor size and nature of the electrophilic trap. Further, the panel contains one of the most potent peptide-based pan-proteasome inhibitors reported to date.     

Substrate Activity Screening with Kinases: Discovery of Small‐Molecule Substrate‐Competitive c‐Src Inhibitors

Substrate‐competitive kinase inhibitors represent a promising class of kinase inhibitors, however, there is no methodology to selectively identify this type of inhibitor. Substrate activity screening was applied to tyrosine kinases. By using this methodology, the first small‐molecule substrates for any protein kinase were discovered, as well as the first substrate‐competitive inhibitors of c‐Src with activity in both biochemical and cellular assays. Characterization of the lead inhibitor demonstrates that substrate‐competitive kinase inhibitors possess unique properties, including cellular efficacy that matches biochemical potency and synergy with ATP‐competitive inhibitors.     

来源于天然产物的基质金属蛋白酶(MMPs)抑制剂

基质金属蛋白酶（MMPs）参与一系列重大疾病的病理过程,基质金属蛋白酶抑制剂具有广阔的药用前景。本文概述了基质金属蛋白酶抑制剂的研究历史和最新的研究理念。重点回顾总结了天然产物中基质金属蛋白酶的活性抑制成分和对基质金属蛋白酶转录表达抑制的天然产物成分以及这些化合物的抗癌效果。     

Plant proteinases and inhibitors: an overview of biological function and pharmacological activity

Proteinases play a fundamental metabolic role during the life cycle in the plant kingdom. By interacting with endogenous or exogenous inhibitors, the proteolytic activity is modulated to meet metabolic requirements. By probing proteolytic enzymes with their inhibitors, it is possible to identify novel functions unrelated to their proteolytic activity. A group of plant proteolytic enzymes stands as a line of defence against environmental changes as their activation is triggered following various types of stress. On the other hand, plants also contain proteinase inhibitors as countermeasures for their protection against insects and pests. Both proteinases and inhibitors emerge as useful tools to combat human diseases. This review focuses on the biochemical characterization of plant proteinases, their inhibitors, the pharmacological potential of proteinases and inhibitors, and new putative emerging functions of proteolytically inhibited proteinases.     

A Study on Inhibitors for the Prevention of Hydrate Formation in Gas Transmission Pipeline

Gas Hydrate is usually formed during the transportation and treatment of oil and gas, resulting in the plugging of gas pipeline and equipment. Three thermodynamic calculation formulas are analyzed to deal with this problem. The lowering of the freezing point of the inhibitors AT is used to calculate the formation temperature of natural gas hydrates. This is considered to be a good approach because it is not limited by what kind and what concentration of inhibitors one uses. Besides, the rate of lowering of the freezing point could be easily measured. The result of testing methanol and mono-ethylene glycol in a reactor shows that adding 10% inhibitors to the reactor can prevent the hydrates formation. Kinetic inhibitors are favored in the present research. They are divided into two types, polymer and surface-active agents. Their characteristics, mechanisms, and application prospect are separately discussed. Polymer inhibitors exhibit better efficiency. The result of field application of VC-713 inhibiter is also given in this article. In practice, the combination of thermodynamic inhibitors and kinetic inhibitors gives better result.     

有机铜作为润滑油高温抗氧剂的研究

在高档的润滑油中除了加有主抗氧剂ZnDTP外，还需加入其它助抗氧剂以弥补其高温抗氧性的不足。本研究合成了几种有机铜盐高温抗氧剂，用DTA法评价了它们及一些常用抗氧剂对润滑油的热稳定性的影响，发现铜铜盐的高温抗氧性能比一些常用抗氧剂好，可满足高档油的需求。     

Quantitation of VEGFR2 (vascular endothelial growth factor receptor) inhibitors – review of assay methodologies and perspectives

The introduction of small‐molecule tyrosine kinase VEGFR2 (vascular endothelial growth factor receptor) inhibitors has added another dimension in the treatment of several oncology indications as they offer a unique mechanism. The VEGFR2 inhibitors have demonstrated superior benefits in treating certain types of cancer, such as renal cell carcinoma and hepatocellular carcinoma, as a monotherapy option. Many of the approved VEGFR2 inhibitors have also shown promise when used in combination with other anticancer agents. There are numerous bioanalytical methods published for the analysis of VEGFR2 inhibitors in preclinical and clinical samples. This review covers VEGFR2 inhibitors such as sunitinib, sorafenib, pazopanib and JI‐101. In addition to providing a comprehensive review of the available methods for the above‐mentioned VRGFR2 inhibitors, it also provides information on assays that can simultaneously measure multiple tyrosine kinase inhibitors, including VEGFR2 molecules. Based on the review, the published methodologies using LC/MS‐MS or HPLC‐UV are adequate for the quantification of the VEGFR2 inhibitors and can easily be established in a modern day bioanalytical laboratory. The availability of a plethora of assays for multiple tyrosine kinase inhibitors makes it easy to analyze a panel of compounds to support either therapeutic drug monitoring and/or clinical pharmacokinetics. Copyright © 2014 John Wiley & Sons, Ltd.     

Squash inhibitors: from structural motifs to macrocyclic knottins

In this article, we will first introduce the squash inhibitor, a well established family of highly potent canonical serine proteinase inhibitors isolated from Cucurbitaceae. The squash inhibitors were among the first discovered proteins with the typical knottin fold shared by numerous peptides extracted from plants, animals and fungi. Knottins contain three knotted disulfide bridges, two of them arranged as a Cystine-Stabilized Beta-sheet motif. In contrast to cyclotides for which no natural linear homolog is known, most squash inhibitors are linear. However, Momordica cochinchinensis Trypsin Inhibitor-I and (MCoTI-I and -II), 34-residue squash inhibitors isolated from seeds of a common Cucurbitaceae from Vietnam, were recently shown to be macrocyclic. In these circular squash inhibitors, a short peptide linker connects residues that correspond to the N- and C-termini in homologous linear squash inhibitors. In this review we present the isolation, characterization, chemical synthesis, and activity of these macrocyclic knottins. The solution structure of MCoTI-II will be compared with topologically similar cyclotides, homologous linear squash inhibitors and other knottins, and potential applications of such scaffolds will be discussed.     

Emerging Therapeutic Agents for Colorectal Cancer

There are promising new therapeutic agents for CRC patients, including novel small-molecule inhibitors and immune checkpoint blockers. We focused on emerging CRC’s therapeutic agents that have shown the potential for progress in clinical practice. This review provides an overview of tyrosine kinase inhibitors targeting VEGF and KIT, BRAF and MEK inhibitors, TLR9 agonist, STAT3 inhibitors, and immune checkpoint blockers (PD1/PDL-1 inhibitors), for which recent advances have been reported. These new agents have the potential to provide benefits to CRC patients with unmet medical needs.     

Recent Advances in BTK Inhibitors for the Treatment of Inflammatory and Autoimmune Diseases

Bruton’s tyrosine kinase (BTK) plays a crucial role in B-cell receptor and Fc receptor signaling pathways. BTK is also involved in the regulation of Toll-like receptors and chemokine receptors. Given the central role of BTK in immunity, BTK inhibition represents a promising therapeutic approach for the treatment of inflammatory and autoimmune diseases. Great efforts have been made in developing BTK inhibitors for potential clinical applications in inflammatory and autoimmune diseases. This review covers the recent development of BTK inhibitors at preclinical and clinical stages in treating these diseases. Individual examples of three types of inhibitors, namely covalent irreversible inhibitors, covalent reversible inhibitors, and non-covalent reversible inhibitors, are discussed with a focus on their structure, bioactivity and selectivity. Contrary to expectations, reversible BTK inhibitors have not yielded a significant breakthrough so far. The development of covalent, irreversible BTK inhibitors has progressed more rapidly. Many candidates entered different stages of clinical trials; tolebrutinib and evobrutinib are undergoing phase 3 clinical evaluation. Rilzabrutinib, a covalent reversible BTK inhibitor, is now in phase 3 clinical trials and also offers a promising future. An analysis of the protein–inhibitor interactions based on published co-crystal structures provides useful clues for the rational design of safe and effective small-molecule BTK inhibitors.     

Molecular docking and competitive binding study discovered different binding modes of microsomal prostaglandin E synthase-1 inhibitors

Microsomal prostaglandin E synthase-1 (mPGES-1) is a newly recognized therapeutic target for the treatment of inflammation, pain, cancer, atherosclerosis, and stroke. Many mPGES-1 inhibitors have been discovered. However, as the structure of the binding site is not well-characterized, none of these inhibitors was designed based on the mPGES-1 structure, and their inhibition mechanism remains to be fully disclosed. Recently, we built a new structural model of mPGES-1 which was well supported by experimental data. Based on this model, molecular docking and competition experiments were used to investigate the binding modes of four representive mPGES-1 inhibitors. As the inhibitor binding sites predicted by docking overlapped with both the substrate and the cofactor binding sites, mPGES-1 inhibitors might act as dual-site inhibitors. This inhibitory mechanism was further verified by inhibitor-cofactor and inhibitor-substrate competition experiments. To investigate the potency-binding site relationships of mPGES-1 inhibitors, we also carried out molecular docking studies for another series of compounds. The docking results correlated well with the different inhibitory effects observed experimentally. Our data revealed that mPGES-1 inhibitors could bind to the substrate and the cofactor binding sites simultaneously, and this dual-site binding mode improved their potency. Future rational design and optimization of mPGES-1 inhibitors can be carried out based on this binding mechanism.     

Studies of the mechanism of selectivity of protein tyrosine phosphatase 1B (PTP1B) bidentate inhibitors using molecular dynamics simulations and free energy calculations

Bidentate inhibitors of protein tyrosine phosphatase 1B (PTP1B) are considered as a group of ideal inhibitors with high binding potential and high selectivity in treating type II diabetes. In this paper, the binding models of five bidentate inhibitors to PTP1B, TCPTP, and SHP-2 were investigated and compared by using molecular dynamics (MD) simulations and free energy calculations. The binding free energies were computed using the Molecular Mechanics/Poisson-Boltzmann Surface Area (MM/PBSA) methodology. The calculation results show that the predicted free energies of the complexes are well consistent with the experimental data. The Molecular Mechanics/Generalized Born Surface Area (MM/GBSA) free energy decomposition analysis indicates that the residues ARG24, ARG254, and GLN262 in the second binding site of PTP1B are essential for the high selectivity of inhibitors. Furthermore, the residue PHE182 close to the active site is also important for the selectivity and the binding affinity of the inhibitors. According to our analysis, it can be concluded that in most cases the polarity of the portion of the inhibitor that binds to the second binding site of the protein is positive to the affinity of the inhibitors while negative to the selectivity of the inhibitors. We expect that the information we obtained here can help to develop potential PTP1B inhibitors with more promising specificity.     

Discovery of Fuchsone Derivatives as Novel Nonpeptide Inhibitor of Caspase-3

Many degenerative diseases caused by uncontrolled cell death can be intervened pharmaceutically through inhibiting caspase-3 activity that leads to cell apoptosis. Here is presented the discovery of rosolic acid and phe- nolphthalein methyl ester, which both belong to fuchsone derivatives, as novel and potent nonpeptide inhibitors of caspase-3. They show high inhibitory potency against caspase-3 in vitro(IC50=0.28 and 0.13 μmol/L). Molecular modeling study provided further an insight into the interaction of phenolphthalein methyl ester with activated caspase-3. The structures of the present small-molecule caspase-3 inhibitors are different from the structures of known caspase-3 inhibitors, so the inhibitors were likely to provide some information for the discovery of anti-caspase-3 inhibitors.     

Confirming target engagement for reversible inhibitors in vivo by kinetically tuned activity-based probes

The development of small-molecule inhibitors for perturbing enzyme function requires assays to confirm that the inhibitors interact with their enzymatic targets in vivo. Determining target engagement in vivo can be particularly challenging for poorly characterized enzymes that lack known biomarkers (e.g., endogenous substrates and products) to report on their inhibition. Here, we describe a competitive activity-based protein profiling (ABPP) method for measuring the binding of reversible inhibitors to enzymes in animal models. Key to the success of this approach is the use of activity-based probes that show tempered rates of reactivity with enzymes, such that competition for target engagement with reversible inhibitors can be measured in vivo. We apply the competitive ABPP strategy to evaluate a newly described class of piperazine amide reversible inhibitors for the serine hydrolases LYPLA1 and LYPLA2, two enzymes for which selective, in vivo active inhibitors are lacking. Competitive ABPP identified individual piperazine amides that selectively inhibit LYPLA1 or LYPLA2 in mice. In summary, competitive ABPP adapted to operate with moderately reactive probes can assess the target engagement of reversible inhibitors in animal models to facilitate the discovery of small-molecule probes for characterizing enzyme function in vivo.     

Small molecule inhibitors of the MDM2-p53 interaction discovered by ensemble-based receptor models

Five nonpeptide, small-molecule inhibitors of the human MDM2-p53 interaction are presented, and each inhibitor represents a new scaffold. The most potent compound exhibited a Ki of 110 +/- 30 nM. These compounds were identified using our multiple protein structure (MPS) method which incorporates protein flexibility into a receptor-based pharmacophore model that identifies appropriate hotspots of binding. Docking the inhibitors with an induced-fit docking protocol suggested that the inhibitors mimicked the three critical binding residues of p53 (Phe19, Trp23, and Leu26). Docking also predicted a new orientation of the scaffolds that more fully fills the binding cleft, enabling the inhibitors to take advantage of additional hydrogen-bonding possibilities not explored by other small molecule inhibitors. One inhibitor in particular was proposed to probe the hydrophobic core of the protein by taking advantage of the flexibility of the binding cleft floor. These results show that the MPS technique is a promising advance for structure-based drug discovery and that the method can truly explore broad chemical space efficiently in the quest to discover potent, small-molecule inhibitors of protein-protein interactions. Our MPS technique is one of very few ensemble-based techniques to be proven through experimental verification of the discovery of new inhibitors.     

多肽抑制剂抑制淀粉质多肽42构象转换的分子动力学模拟和结合自由能计算

应用分子动力学模拟和结合自由能计算方法研究了多肽抑制剂KLVFF、VVIA和LPFFD抑制淀粉质多肽42 (Aβ42)构象转换的分子机理. 结果表明, 三种多肽抑制剂均能够有效抑制Aβ42的二级结构由α-螺旋向β-折叠的构象转换. 另外, 多肽抑制剂降低了Aβ42分子内的疏水相互作用, 减少了多肽分子内远距离的接触, 有效抑制了Aβ42的疏水塌缩, 从而起到稳定其初始构象的作用. 这些抑制剂与Aβ42之间的疏水和静电相互作用(包括氢键)均有利于它们抑制Aβ42的构象转换. 此外, 抑制剂中的带电氨基酸残基可以增强其和Aβ42之间的静电相互作用(包括氢键), 并降低抑制剂之间的聚集, 从而大大增强对Aβ42构象转换的抑制能力. 但脯氨酸的引入会破坏多肽的线性结构, 从而大大降低其与Aβ42 之间的作用力. 上述分子模拟的结果揭示了多肽抑制剂KLVFF、VVIA和LPFFD抑制Aβ42构象转换的分子机理, 对于进一步合理设计Aβ的高效短肽抑制剂具有非常重要的理论指导意义.     

解吸附电晕束电离质谱法快速筛选保健食品中非法添加的5型磷酸二酯酶抑制剂

建立了解吸附电晕束离子源(DCBI)结合离子阱质谱快速检测保健食品中非法添加的3种磷酸二酯酶5(PDE5)抑制剂(伐地那非、西地那非、他达拉非)的方法。采用一级质谱筛选,二级质谱确证,对样品中非法添加物进行定性鉴别;通过二级特征碎片离子进行半定量分析,并与传统高效液相色谱-紫外(HPLC-UV)定量检测法对比。对12个市售保健品进行检测,DCBI-MS定性检测结果与HPLC-UV检测结果一致,有7个样品检出他达拉非,3个样品检出西地那非,1个样品检出伐地那非。通过研究3种PDE5抑制剂的二级质谱裂解规律,推测一个样品中含有羟基豪莫西地那非。本方法快速准确,适用于大批量复杂基质样品中PDE5抑制剂的筛查。