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At least 793 records · Page 44Linked to original sources

Structure-activity relationships of the peptide deformylase inhibitor BB-3497: modification of the metal binding group.

A series of analogues of the potent peptide deformylase (PDF) inhibitor BB-3497 containing alternative metal binding groups was synthesised. Enzyme inhibition and antibacterial activity data for these compounds revealed that the bidentate hydroxamic acid and N-formyl hydroxylamine structural motifs represent the optimum chelating groups on the pseudopeptidic BB-3497 backbone.

Amidohydrolases↗

Stereochemical aspects of iron transport in Mycelia sterilia EP-76.

Chromic complexes of N,N',N''-triacetylfusarinine C have been prepared and examined for biological activity in Mycelia sterilia EP-76. The iron transport system of this organism recognizes only the lambda coordination isomer of Cr(III)-triacetylfusarinine C even though the delta configuration predominates in solution. Chromium is excreted into the medium following triacetylfusarinine C-mediated uptake of the metal. Hydrogenation of the double bonds conjugated to the hydroxamic acid functions of triacetylfusarinine C yields four chromatographically distinct ferric complexes. Two of the complexes have the lambda configuration, while the other two have the opposite (delta) configuration. The complexes differ in effectiveness as siderophores in M. sterilia EP-76, the lambda isomers being most active.

Biological Transport↗

Discovery of potent and selective succinyl hydroxamate inhibitors of matrix metalloprotease-3 (stromelysin-1).

Structure activity relationships are described for a series of succinyl hydroxamic acids 4a-o as potent and selective inhibitors of matrix metalloprotease-3 (stromelysin-1). Optimisation of P1' and P3' groups gave compound 4j (MMP-3 IC50=5.9nM) which was >140-fold less potent against MMP-1 (IC50=51,000nM), MMP-2 (IC50=1790nM), MMP-9 (IC50=840nM) and MMP-14 (IC50=1900nM).

Hydroxamic Acids↗

Discovery of 3-OH-3-methylpipecolic hydroxamates: potent orally active inhibitors of aggrecanase and MMP-13.

A series of 3-hydroxy-3-methylpipecolic hydroxamate inhibitors of MMP-13 and aggrecanase was designed based on the observation of increased aggrecanase activity with substitution at the 3-position of the piperidine ring. Potency versus aggrecanase was optimized by modification of the benzyloxyarylsulfonamide group that binds in the S1' pocket. These compounds also possess markedly improved bioavailability and lower metabolic clearance compared to analogous 3,3-dimethyl-5-hydroxypipecolic hydroxamates. These improvements are attributed to lowered lipophilicity proximal to the metabolically labile hydroxamic acid. Synthesis, structure activity relationships, and in vivo efficacy data are described.

Administration, Oral↗

Amide analogues of TSA: synthesis, binding mode analysis and HDAC inhibition.

The synthesis of new amide type histone deacetylase inhibitors is described, having an (R)-methyl substituent and a diene or saturated structure of the chain linking the hydroxamic acid and dimethylaminobenzoyl groups. The saturated compound shows stronger HDAC inhibition than the unsaturated analogue. Molecular modeling suggests that the flexibility of the linker chain is important for an optimal orientation of the dimethylaminobenzoyl group in the enzyme.

Amides↗

A liquid chromatography-electrospray ionization tandem mass spectrometric assay for quantitation of the histone deacetylase inhibitor, vorinostat (suberoylanilide hydroxamicacid, SAHA), and its metabolites in human serum.

Vorinostat (suberoylanilide hydroxamic acid, SAHA) is undergoing evaluation as an antineoplastic agent. We developed a liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay for quantitating vorinostat and its major metabolites, vorinostat glucuronide and 4-anilino-4-oxobutanoic acid, in human serum. The assay uses: deuterated internal standards; acetonitrile protein precipitation; a BDS Hypersil C18 (3 microm, 100 mm x 3 mm) column; a gradient mobile phase of 0.5% acetic acid in acetonitrile and water; and electrospray positive-mode ionization with selected reaction monitoring (SRM) detection. The lower limit of quantitation was 3.0 ng/ml for each analyte. The assay is being employed in at least 12 clinical studies of vorinostat-containing regimens.

Chromatography, Liquid↗

Hydroxamate based inhibitors of adenylyl cyclase. Part 2: the effect of cyclic linkers on P-site binding.

The adenylyl cyclases (ACs) are a family of enzymes that are key elements of signal transduction by virtue of their ability to convert ATP to cAMP. The catalytic mechanism of this transformation proceeds through initial binding of ATP to the purine binding site (P-site) followed by metal mediated cyclization with loss of pyrophosphate. Previous work in our group identified novel inhibitors which possess an adenine ring joined to a metal-coordinating hydroxamic acid through flexible linkers. Considering the spatial positioning of the metals with respect to the adenine binding site coupled with potentially favorable entropic factors, conformational restriction of the tether through a stereochemistry based SAR employing a rigid cyclic scaffold was explored.

Adenylyl Cyclase Inhibitors↗

Conformational analogues of Oxamflatin as histone deacetylase inhibitors.

Conformational analogues of the hydroxamic acid Oxamflatin compounds, have been synthesised to enable evaluation of the impact of varying the linking section on histone deacetylase inhibition. Preliminary testing indicates treatment of leukaemia cells with each of the analogues leads to significant inhibition of histone deacetylase and reduction in cell growth and proliferation.

Biphenyl Compounds↗

Hydroxamate based inhibitors of adenylyl cyclase. Part 1: the effect of acyclic linkers on P-site binding.

The adenylyl cyclases (ACs) are a family of enzymes that are key elements of signal transduction by virtue of their ability to convert ATP to cAMP. The catalytic mechanism of this transformation proceeds through initial binding of ATP to the purine binding site (P-site) followed by metal mediated cyclization with loss of pyrophosphate. Crystallographic analysis of ACs with known inhibitors reveals the presence of two metals in the active site. Presently, nine isoforms of adenylyl cyclase are known and unique isoform combinations are expressed in a tissue specific manner. The development of isoform specific inhibitors of adenylyl cyclase may prove to be a useful strategy toward the design of novel therapeutic agents. In order to develop novel AC inhibitors, we have chosen a design approach utilizing molecules with the adenine ring system joined to a metal-coordinating hydroxamic acid via flexible acyclic linkers. The designed inhibitors were assayed against type V AC with the size and heteroatom content of the linkers varied to probe the interaction of the nucleotide and metal binding sites within the enzyme.

Adenylyl Cyclase Inhibitors↗

Cyanide-resistant respiration in Neurospora crassa.

Cell respiration in wild type and poky was studied as part of a long-term investigation of cyanide-resistant respiration in Neurospora. Respiration in wild type proceeds via a cytochrome chain which is similar to that of higher organisms; it is sensitive to antimycin A or cyanide. Poky, on the other hand, respires by means of two alternative oxidase systems. One of these is analogous to the wild-type cytochrome chain in that it can be inhibited by antimycin A or cyanide; this system accounts for as much as 15% of the respiration of poky f(-) and 34% of the respiration of poky f(+). The second oxidase system is unaffected by antimycin A or cyanide at concentrations which inhibit the cytochrome chain maximally. It can, however, be specifically inhibited by salicyl hydroxamic acid. The cyanide-resistant oxidase is not exclusive to poky, but is also present in small quantities in wild type grown under ordinary circumstances. These quantities may be greatly increased (as much as 20-fold) by growing wild type in the presence of antimycin A, cyanide, or chloramphenicol.

Aerobiosis↗

Discovery of 3,3-dimethyl-5-hydroxypipecolic hydroxamate-based inhibitors of aggrecanase and MMP-13.

A series of pipecolic hydroxamate inhibitors of MMP-13 and aggrecanase was discovered based on screening known inhibitors of TNF-alpha converting enzyme (TACE). Potency versus aggrecanase was optimized by modification of the benzyloxyarylsulfonamide group. Incorporation of geminal alkyl substitution at the 3-position of the piperidine ring improved metabolic stability, presumably by increasing steric hindrance around the metabolically labile hydroxamic acid. This modification also resulted in dramatic improvement of aggrecanase activity with a slight reduction in selectivity versus MMP-1. Synthesis, structure activity relationships, and strategies to reduce metabolic clearance are described.

Endopeptidases↗

Hydroxamate-based inhibitors of low affinity IgE receptor (CD23) processing.

A series of hydroxamic acids related to the non-selective matrix metalloprotease inhibitor Batimastat is described, which inhibits the proteolytic cleavage of the low affinity IgE receptor from cell membrane preparations. Limited SAR studies suggest that the structural requirements for effective inhibition are distinct from those required for the inhibition of collagenase.

Humans↗

The selection and evaluation of new chelating agents for the treatment of iron overload.

A large-scale systematic evaluation of potential iron chelators for the treatment of hemosiderosis was conducted. The compounds were identified and evaluated using a hypertransfused mouse screen in which deferrioxamine B was a standard. This screen was designed to measure iron depletion in the tissues as well as iron excretion. Groups of 10 previously hypertransfused BDF1 male mice received a single daily i.p. injection of either vehicle, standard, or test compound for 7 days. Iron in daily urine pools and individual spleen and liver homogenates was determined by atomic absorption. More than 70 chelators were evaluated, including natural and synthetic hydroxamic acids, phenols, catechols and tropolones known to have a high affinity for iron (III) in vitro. Ethylenediamine-N,N'-bis(2-hydroxyphenylacetic acid) was shown to be considerably more effective than deferrioxamine B (i.p.) and, in addition, was orally active. Factors determining the efficacy of this and other chelating agents are discussed.

Animals↗

Identification of a potent non-hydroxamate histone deacetylase inhibitor by mechanism-based drug design.

In order to find novel non-hydroxamate histone deacetylase (HDAC) inhibitors, we synthesized several suberoylanilide hydroxamic acid (SAHA)-based compounds designed on the basis of the catalytic mechanism of HDACs. Among these compounds, 5b was found to be as potent as SAHA. Kinetic enzyme assays and molecular modeling suggested that the mercaptoacetamide moiety of 5b interacts with the zinc in the active site of HDACs and removes a water molecule from the reactive site of the deacetylation.

Acetamides↗

Selective inhibition of low affinity IgE receptor (CD23) processing: P1' bicyclomethyl substituents.

Using a variety of alpha-hydroxy hydroxamic acid derivatives, the size and shape of the S1' pocket for the CD23 processing metalloprotease has been explored. It has been demonstrated that a P1' 2-naphthylmethyl group occupies most of the available space and gives excellent selectivity against fibroblast collagenase (matrix metalloproteinase-1, MMP-1) and other MMPs.

Bridged Bicyclo Compounds↗

Histone deacetylase inhibitors up-regulate the expression of tight junction proteins.

Histone deacetylase (HDAC) inhibitors promote cell maturation, differentiation, and apoptosis through changes in gene expression. Differentiated epithelial cells are characterized by apical tight junctions (TJ), which play a role in cell-cell adhesion, polarity, and the permeability barrier function of epithelia. The relationship between cellular differentiation and expression of TJ-associated proteins is not known. Here, we investigated whether HDAC inhibitors affect the expression of TJ proteins in cultured cells by immunoblotting, immunofluorescence, and quantitative real-time, reverse transcription-PCR. We find that the HDAC inhibitor sodium butyrate significantly up-regulates the protein levels of cingulin, ZO-1, and ZO-2 in Rat-1 fibroblasts, cingulin in COS-7 cells, and cingulin and occludin in HeLa cells. Levels of mRNA for cingulin, ZO-1, and ZO-2 are also increased in sodium butyrate-treated Rat-1 fibroblasts. Up-regulation of cingulin is reversible and dose dependent and requires de novo protein synthesis and protein kinase activity, because it is inhibited by cycloheximide and by the protein kinase inhibitor H-7. Up-regulation of TJ proteins by sodium butyrate is linked to the ability of sodium butyrate to inhibit HDAC activity, because suberoylanilide hydroxamic acid, a HDAC inhibitor of a different structural class, also up-regulates cingulin, ZO-1, and ZO-2 expression in Rat-1 fibroblasts. These results indicate that cellular differentiation correlates with kinase-dependent up-regulation of the expression of specific TJ proteins.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

Synthesis and 5-lipoxygenase inhibitory activity of 5-hydroperoxy-6,8,11,14-eicosatetraenoic acid analogues.

A series of eicosatetraenes (2-24) were designed, synthesized, and evaluated in vitro for inhibitory activity against 5-lipoxygenase (20000g supernatant from homogenized rat basophilic leukemia cells). All compounds were found to be active with the potencies (IC50's) ranging from 0.19 to 97 microM. Compounds containing the hydroxamic acid functionality (10-12) exhibited the best activity (IC50 = 0.19-2.8 microM). The most potent inhibitor was 5-[(hydroxyamino)carbonyl]methyl]-6,8,11,14-eicosatetraenoic acid (11), which was 10 times more active than the C-1 hydroxamates of arachidonic acid or 5-HETE. Cyclization of the linear eicosanoids 2 and 14 in the C-1 to C-5 region produced compounds (21 and 24, respectively) with several-fold greater potency.

Animals↗

Plasma pharmacokinetics and metabolism of the histone deacetylase inhibitor trichostatin a after intraperitoneal administration to mice.

Trichostatin A is a potent and specific histone deacetylase inhibitor with promising antitumor activity in preclinical models. Plasma pharmacokinetics of trichostatin A were studied following single-dose intraperitoneal administration of 80 mg/kg (high dose) or 0.5 mg/kg (low dose) to female BALB/c mice. Plasma trichostatin A concentrations were quantified by high performance liquid chromatography (HPLC)-UV assay (high dose) or by HPLC-multiple reaction monitoring assay (low dose). Trichostatin A was rapidly absorbed from the peritoneum and detectable in plasma within 2 min. Cmax of 40 microg/ml and 8 ng/ml occurred within 5 min, followed by rapid exponential decay in plasma trichostatin A concentration with t1/2 of 6.3 min and 9.6 min (high and low doses, respectively). Phase I metabolites at the high dose were identified by simultaneous UV and positive ion electrospray mass spectrometry. Trichostatin A underwent extensive metabolism: primary metabolic pathways were N-demethylation, reduction of the hydroxamic acid to the corresponding trichostatin A amide, and oxidative deamination to trichostatic acid. N-Monomethyl trichostatin A amide was the major plasma metabolite. No didemethylated compounds were identified. Trichostatic acid underwent further biotransformation: reduction and beta-oxidation of the carboxylic acid, with or without N-demethylation, resulted in formation of dihydro trichostatic acid and dinor dihydro trichostatic acids. HPLC fractions corresponding to trichostatin A and N-demethylated trichostatin A exhibited histone deacetylase-inhibitory activity; no other fractions were biologically active. We conclude that trichostatin A is rapidly and extensively metabolized in vivo following intraperitoneal administration to mice, and N-demethylation does not compromise histone deacetylase-inhibitory activity.

Animals↗