Structure-based design of a new series of D-glutamic acid based inhibitors of bacterial UDP-N-acetylmuramoyl-L-alanine:D-glutamate ligase (MurD)

MurD ligase is one of the key enzymes participating in the intracellular steps of peptidoglycan biosynthesis and constitutes a viable target in the search for novel antibacterial drugs to combat bacterial drug-resistance. We have designed, synthesized, and evaluated a new series of D-glutamic acid-based Escherichia coli MurD inhibitors incorporating the 5-benzylidenethiazolidin-4-one scaffold. The crystal structure of 16 in the MurD active site has provided a good starting point for the design of structurally optimized inhibitors 73-75 endowed with improved MurD inhibitory potency (IC(50) between 3 and 7 μM). Inhibitors 74 and 75 showed weak activity against Gram-positive Staphylococcus aureus and Enterococcus faecalis. Compounds 73-75, with IC(50) values in the low micromolar range, represent the most potent D-Glu-based MurD inhibitors reported to date.     

花生四烯酸代谢网络研究：从关键酶的单靶标抑制剂到多靶标抑制剂

炎症引发的疾病是人类常见的免疫系统疾病, 医药市场对抗炎药物的需求量极大。花生四烯酸代谢网络是产生炎症介质的主要网络, 网络中的一些蛋白质已成为抗炎药物设计的重要靶标, 但这些单靶标药物不能很好地控制网络的平衡,同时容易引起副作用。大多数炎症引发的疾病是由多级联炎症代谢共同影响的结果,  为了更好地治疗这类由多个药靶参与调控的复杂疾病, 发展针对花生四烯酸代谢网络的多靶标药物具有迫切性。本文综述花生四烯酸代谢网络的关键靶标 (如磷脂酶A2、环氧合酶、5-脂氧合酶和白三烯A4水解酶等) 的特异性抑制剂和多靶标抑制剂研究进展。     

Thiol-dependent enzymes and their inhibitors: a review

Biological thiol-dependent enzymes have recently received extensive attention in the literature because of their involvement in a variety of physiopathological conditions. The active thiol groups of these enzymes are derived from the cysteine residues present. Hence, in a biological system, the selective reversible or irreversible inhibition of the activity of these enzymes by modification of the thiol moiety may potentially lead to the development of a chemotherapeutic treatment. Despite all the research efforts involved in the attempt to develop potential chemotherapeutic treatments for the major diseases involving cysteine proteases, there are in fact no such treatments available yet. However, AG7088 (1) an inhibitor of rhinovirus-3C is in phase II/III clinical trial for the treatment of common cold and VX-740 (2, pralnacasan) an inhibitor of caspase-1 is in phase II clinical trial as an anti-inflammatory agent for rheumatoid arthritis. Several other cysteine protease inhibitors (i.e., cathepsin K, and S) are in pre-clinical evaluation or pre-clinical development. Structure-based drug design approaches have been instrumental in the development of these inhibitors. Intensive biochemical studies on the cysteine proteases have shed some light on some potential targets for therapeutic development. In addition, new techniques and new ideas are constantly emerging. As such, an up-to-date review of the literature on thiol-dependent enzymes as potential targets and their inhibitors designed from peptidic, modified peptidomimetic scaffolds and from small heterocyclic molecules is presented.     

Hydroxyperfluoroazobenzenes: novel inhibitors of enzymes of androgen biosynthesis

In a search for inhibitors of 17 alpha-hydroxylase-C17,20-lyase and testosterone-5 alpha-reductase, target enzymes in the development of drugs to treat hormone-dependent prostatic cancer, we have identified certain compounds chemically derived by the hydrolysis of decafluoroazobenzene (4) as novel inhibitors for these two enzymes. Hydrolysis of 4 gave the known 4-hydroxynonafluoroazobenzene (1) and the novel 2-hydroxynonafluoroazobenzene (2). By AlI3 demethylation of 4,4'-dimethoxyoctafluoroazobenzene (5) or by hydrolysis of 4 under phase-transfer conditions 4,4'-dihydroxyoctafluoroazobenzene (3) was obtained. Compounds 1 and 2 were inhibitors of the hydroxylase (IC50 values, respectively, 30 and 63 microM) and of the lyase (IC50 values 33 and 16 microM) steps on the pathway of androgen biosynthesis. The 2-hydroxy compound 2 underwent spontaneous conversion into octafluorodibenz[b,f][1,4,5]oxadiazepine (6) which had IC50 values, respectively, of 50 and 15 microM for the hydroxylase and lyase steps and which contributed to the observed activity of 2. Effective inhibitors of the 5 alpha-reductase were 1 (Ki 10 microM) and 3 (Ki4 microM): the activities of 1 and 3 were markedly pH dependent, with respective IC50 values of 14 and 5 microM at pH 7.4 and of 2 and 0.8 microM at pH 6.6.     

Efflux pump inhibitors in bacteria

The efficacy of antibiotherapy of infectious diseases is strongly compromised by the advent and spread of antibiotic resistance. Active efflux of cytotoxic drugs mediated by multi-drug transporters is the basis of multi-drug resistance in prokaryotic cells. Thus, inhibition of efflux pumps appears to be a promising strategy to combat multi-drug resistance pathogens. Different classes of inhibitors structurally unrelated have been patented in the last decade.     

Dual inhibitors of the blood coagulation enzymes

The search for an ideal anticoagulant has spanned decades and has resulted in several approaches and the identification of novel target molecules for preventing and treating thrombosis. The first group of new anticoagulant agents acting through direct inhibition of coagulation factors were inhibitors of thrombin, but factor Xa inhibitors and, most recently, factor VIIa inhibitors have become attractive candidates. The structures of thrombin, factor Xa and factor VIIa show similarities in their active sites and, for this reason, attempts have been made to develop synthetic agents containing in a single molecule inhibitory activity against two of the enzymes of the blood coagulation cascade. Such dual inhibitors are now in preclinical studies and are, potentially, new anticoagulant drugs with improved properties. The emphasis of this review will be placed on dual inhibitors of thrombin/factor Xa and factor Xa/factor VIIa. Comparison of the active sites of these enzymes is included for better understanding of the structural demands to be met in designing effective dual inhibitors.     

Acid-sensitive latent inhibitors for proteolytic enzymes: synthesis and characterization

The reaction between peptide aldehydes and acylhydrazones affords derivatives that represent potential prodrugs for selective inhibition of lysosomal enzymes. BzPheal = Ala, obtained from the reaction between N-benzoyl-L-phenylalaninal and N-acetyl-L-alanine hydrazide, has been most carefully studied. When BzPheal = Ala is introduced into ongoing reactions catalyzed by alpha-chymotrypsin or papain, the rate of these reactions diminishes more rapidly with time than do those of controls lacking BzPheal = Ala. Furthermore, the disparity between run and control is much greater at pH 5 than at pH 7. The extent of inhibition (defined as explained in the text) at pH 5 can exceed that at pH 7 by 25-40-fold. The data are quantitatively explained by a reaction scheme that recognizes three important properties of BzPheal = Ala: (1) It undergoes hydrolysis at pH 5-7 to regenerate N-benzoyl-L-phenylalaninal; (2) the aldehyde thus liberated is a far more potent inhibitor for serine or cysteine proteases than is BzPheal = Ala; and (3) the rate constant for hydrolysis of BzPheal = Ala at pH 5 greatly exceeds that at pH 7.     

不同产地萝芙木药材质量评价

目的 对不同产地萝芙木药材进行质量评价,为萝芙木药材质量标准修订提供依据.方法 收集市场上不同产地萝芙木药材,应用RP-HPLC法测定不同产地萝芙木药材样本中利血平含量.结果 不同产地萝芙木药材中利血平含量差异显著,入药部位为主要因素,以云南萝芙木根部含量最高.结论 市场上不同产地萝芙木药材在质量上存在差异.     

Synthesis of natural product-inspired inhibitors of Mycobacterium tuberculosis mycothiol-associated enzymes: the first inhibitors of GlcNAc-Ins deacetylase

Synthesis and evaluation of a chemical library of inhibitors of the mycothiol biosynthesis enzyme GlcNAc-Ins deacetylase (MshB) and the mycothiol-dependent detoxification enzyme mycothiol- S-conjugate amidase (MCA) from Mycobacterium tuberculosis are reported. The library was biased to include structural features of a group of natural products previously shown to competitively inhibit MCA. Molecular docking studies that reproducibly placed the inhibitors in the active site of the enzyme MshB reveal the mode of binding and are consistent with observed biological activity.     

Interactions between oxotremorine and inhibitors of Cholinesterase enzymes

Interactions between oxotremorine and physostigmine or dyflos have been investigated in mice using doses giving approximately 50% inhibition of mouse brain cholinesterase. Oxotremorine LD50 was unaffected by pretreatment of mice with the anticholinesterases. Its ED50 (tremor) was decreased by physostigmine and neostigmine but not by dyflos. Dyflos antagonized oxotremorine hypothermia, physostigmine was without effect. Oxotremorine did not alter the inhibitory activity of the anticholinesterases. The lack of potentiation of oxotremorine by cholinesterase inhibitors suggests it acts directly in these tests by a mechanism independent of its ability to increase tissue acetylcholine concentration.     

不同类型的抗菌药物对细菌内毒素释放的影响

目的：探讨不同类型的抗菌药物释放细菌内毒素潜能和速率的不同。方法;选择５种不同类型抗菌药物单独或联合作用于大肠埃希氏菌,比较４ｈ期间游离内毒素,同时作菌落计数和细菌形态学检查,结果：亚胺同／西司他丁杀菌作用和释放内毒素最快,但释放内毒素量较少,头孢他啶释放内毒素较快而量较多;环丙沙星释放缓慢并中量;阿米卡星释放缓慢且量最小;头孢曲松致细菌丝状体形成,杀菌并释放内毒素最慢但量最大;阿米卡星和头孢曲松     

Equally potent inhibitors of cholesterol synthesis in human hepatocytes have distinguishable effects on different cytochrome P450 enzymes

Six 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (the present cholesterol-lowering drugs known as statins), lovastatin (L), simvastatin (S), pravastatin (P), fluvastatin (F), atorvastatin (A) and cerivastatin (C) are shown to be potent inhibitors of cholesterol synthesis in human hepatocytes, the target tissue for these drugs in man. All six inhibited in the nM range (IC(50) values: 0.2-8.0 nM). As daily used cholesterol-lowering drugs they are likely coadministered with other drugs. While several cytochrome P450 (CYP) enzymes are involved in drug metabolism in the liver and thus play an important role in drug-drug interaction it was investigated which of these enzymes are influenced by the active forms of the six statins. These enzyme activities were studied in human liver microsomal preparations, and in simian and human hepatocytes in primary culture. The following CYP reactions were used: nifedipine aromatization (CYP3A4), testosterone 6beta-hydroxylation (CYP3A4), tolbutamide methylhydroxylation (CYP2C9), S-mephenytoin 4-hydroxylation (CYP2C19), bufuralol 1'-hydroxylation (CYP2D6), aniline 4-hydroxylation (CYP2E1), coumarin 7-hydroxylation (CYP2A6) and 7-ethoxyresorufin O-dealkylation (CYP1A1/2). In the human liver microsomes the statins (concentrations up to 400 microM) did not influence the CYP1A1/2 activity and hardly the CYP2A6 and CYP2E1 activities. Except P, the other five statins were stronger inhibitors of the CYP2C19 activity with IC(50) values around 200 microM and the same holds for the effect of A, C and F on the CYP2D6 activity. L and S were weaker inhibitors of the latter enzyme activity, whereas P did not influence both activities. About the same was observed for the statin effect on CYP2C9 activity, except that F was a strong inhibitor of this activity (IC(50) value: 4 microM). Using the assay of testosterone 6beta-hydroxylation the CYP3A4 activity was decreased by L, S and F with IC(50) values of about 200 microM and a little more by C and A (IC(50) around 100 microM). P had hardly an effect on this activity. To a somewhat less extent the same trend was seen when CYP3A4 activity was measured using nifedipine as substrate. The inhibitory effects observed in microsomes were verified in suspension culture of freshly isolated hepatocytes from Cynomolgus monkey (as a readily available model) and of human hepatocytes. In general the same trends were seen as in the human microsomes, except that in some cases the inhibition of the CYP activity was less, possibly by the induction of the particular CYP enzyme by incubation of the cells with a particular statin. F remained a strong inhibitor of CYP2C9 activity in human and monkey hepatocytes. A induced the CYP2C9 in monkey hepatocytes but was an inhibitor of the CYP2C9 in human hepatocytes. A, S, L and C were moderate inhibitors in both cellular systems of CYP3A4. P was not affecting any of the CYP activities in the three systems studied. It is concluded that different CYP enzymes interact with different statins and therefore differences in between these drugs are to be expected when drug-drug interaction is considered.     

Derivatives of 3-hydroxypyridine as inhibitors of proteolytic enzymes

Translated from Khimiko-farmatsevticheskii Zhurnal, Vol. 23, No. 2, pp. 133–135, February, 1989.     

Kinetic studies of novel inhibitors of endomorphin degrading enzymes

Endomorphins (EMs), two endogenous μ-opioid receptor selective ligands, are attractive lead compounds for opioid-based pain management studies. However, these peptides are quickly degraded by peptidases, in particular by dipeptidylpeptidase IV (DPP IV) and aminopeptidase M (APM). Targeting enzymatic degradation is one approach to prolong endomorphin activity. In this study we characterized the action of two new inhibitors of similar to endomorphins structure, Tyr-Pro-Ala-NH(2) (EMDB-2) and Tyr-Pro-Ala-OH (EMDB-3), which were designed earlier in our laboratory. The presented data give evidence that EMDB-2 and EMDB-3 are potent inhibitors of enzymes responsible for endomorphin cleavage. These compounds are stable and easily synthesized. EMDB-2 and EMDB-3 are competitive inhibitors of both, DPP IV and APM, with K(i) values in micromolar range. They are less potent than diprotin A in protecting EMs against DPP IV but more potent than actinonin in protecting these peptides against APM.     

Cytochrome p450 enzymes mechanism based inhibitors: common sub-structures and reactivity

The inhibition of human cytochrome P450s (CYPs) is one of the most common mechanisms which can lead to drug-drug interactions. The inhibition of CYPs can be reversible (competitive or non-competitive) or irreversible. Irreversible inhibition usually derives from activation of a drug by CYPs into a reactive metabolite, which tightly binds to the enzyme active site, leading to a long lasting inactivation. This process is called "mechanism based inhibition" or "suicide inhibition". The irreversible inactivation usually implies the formation of a covalent bond between the metabolite and the enzyme, which can lead to hapten formation and can in some cases trigger an autoimmune-response. For these reasons it is of utmost importance to study the mechanism of the CYP inhibition of new potential drugs as early as possible during the drug discovery process. The literature on CYPs is vast and covers numerous aspects of their biology and biochemistry, however to our knowledge there is no general and systematic review focusing on mechanism-based inhibitors; we have reviewed the literature and compiled all the available data on chemical entities, which are known to be CYP suicide inhibitors. Each compound is reported together with its chemical structure, the CYP isoform and the parameters describing the inactivation. Literature references are reported together with their PMID (PubMed ID number) to allow a fast retrieval of the papers. This review offers a quick reference to help predict liabilities of new chemical entities without carrying out extensive in vitro work, and will hopefully help in designing safer drugs.     

Non-thiol farnesyltransferase inhibitors: evaluation of different AA(X)-peptidomimetic substructures in combination with arylic cysteine replacements

In the course of our studies on non-thiol farnesyltransferase inhibitors based on the 2, 5-diaminobenzophenone AAX-peptidomimetic substructure, we have developed the (4-nitrophenyl)butyryl (R(1)), the (2-naphthyl)acryloyl (R(2)), the 4-nitrocinnamoyl (R(3)), and the 5-(4-nitrophenyl)furylacryloyl (R(4)) groups as useful cysteine replacements. In this study, we combined these four groups with other AA(X)-peptidomimetic substructures (5-10: R = H) reported in the literature. The 5-(4-nitrophenyl)furylacryloyl moiety (R(4)) turned out to be the most useful non-thiol cysteine replacement yielding in all cases the most active inhibitors. By combination of this 5-(4-nitrophenyl) furylacryloyl moiety (R(4)) with the structurally simple AAX-peptidomimetics 4-aminobenzophenone (5) and 4-aminodiphenylsulfone (6) potent, readily accessible non-thiol farnesyltransferase inhibitors were obtained (IC(50) = 12 nMand 10 nM).     

New bidentates as full inhibitors of enkephalin-degrading enzymes: synthesis and analgesic properties

New compounds were designed to fully inhibit the in vitro metabolism of enkephalins, ensured by three different metallopeptidases. For this purpose, bidentate ligands as hydroxamate and N-hydroxy-N-formylamino groups were selected as highly potent metal coordinating agents and introduced on Phe-Gly and Phe-Ala related structures. Compounds corresponding to the general formula HC(O)N(OH)CH2CH(CH2Ph)CONHCH2COOH (compound 7) and HN(OH)C(O)CH2CH(CH2Ph)CONHCH(R)COOH (compound 11, R = H; compound 13, R = CH3) behave as full inhibitors of the three enzymes, with IC50's in the nanomolar range for enkephalinase, from 0.3 microM to 1 nM for dipeptidylaminopeptidase, and in the micromolar range for a biologically relevant aminopeptidase. Two diastereoisomers of the most active inhibitor 13 were separated by HPLC and their stereochemistry was assigned by 1H NMR spectroscopy. Both isomers were efficient as enkephalinase blockers, but only the RS isomer, designated kelatorphan, was able to strongly inhibit aminopeptidase and dipeptidylaminopeptidase. Intracerebroventricular injection in mice of these mixed inhibitors, especially kelatorphan, led to naloxone reversible analgesic responses (hot-plate test) that were slightly better than those produced by a mixture of thiorphan and bestatin, two potent inhibitors of enkephalinase and aminopeptidase, respectively. Kelatorphan was also more efficient in potentiating the analgesia induced by a subanalgesic dose of Met-enkephalin. All these results support a physiological role in pain transmission for enkephalinase and a probably synaptic aminopeptidase M.