Discovery of a PCAF Bromodomain Chemical Probe.

The p300/CBP-associated factor (PCAF) and related GCN5 bromodomain-containing lysine acetyl transferases are members of subfamily I of the bromodomain phylogenetic tree. Iterative cycles of rational inhibitor design and biophysical characterization led to the discovery of the triazolopthalazine-based L-45 (dubbed L-Moses) as the first potent, selective, and cell-active PCAF bromodomain (Brd) inhibitor. Synthesis from readily available (1R,2S)-(-)-norephedrine furnished L-45 in enantiopure form. L-45 was shown to disrupt PCAF-Brd histone H3.3 interaction in cells using a nanoBRET assay, and a co-crystal structure of L-45 with the homologous Brd PfGCN5 from Plasmodium falciparum rationalizes the high selectivity for PCAF and GCN5 bromodomains. Compound L-45 shows no observable cytotoxicity in peripheral blood mononuclear cells (PBMC), good cell-permeability, and metabolic stability in human and mouse liver microsomes, supporting its potential for in vivo use.

Synthesis, characterization, biological activity and equilibrium studies of metal(II) ion complexes with tridentate hydrazone ligand derived from hydralazine.

In the present study, a new hydrazone ligand (2-((2-phthalazin-1-yl)hydrazono)methyl)phenol) prepared by condensation of hydralazine (1-Hydralazinophthalazine) with salicylaldehyde (SAH). The synthesized SAH-hydrazone and its metal complexes have been characterized by elemental analyses, IR, (1)H NMR, solid reflectance, magnetic moment, molar conductance, mass spectra, UV-vis and thermal analysis (TGA). The analytical data of the complexes show the formation of 1:1 [M:L] ratio, where M represents Ni(II), Co(II) and Cu(II) ions, while L represents the deprotonated hydrazone ligand. IR spectra show that SAH is coordinated to the metal ions in a tridentate manner through phthalazine-N, azomethine-N and phenolic-oxygen groups. The ligand and their metal chelates have been screened for their antimicrobial activities using the disc diffusion method against the selected bacteria and fungi. Proton-ligand association constants of (SAH) and the stepwise stability constants of its metal complexes are determined potentiometrically in 0.1 M NaNO(3) at different temperatures and the corresponding thermodynamic parameters were derived and discussed. The order of -ΔG° and -ΔH° were found to obey Mn(2+)

Antiatherogenic effect of bisvanillyl-hydralazone, a new hydralazine derivative with antioxidant, carbonyl scavenger, and antiapoptotic properties.

Reactive oxygen species (ROS) generated within the vascular wall trigger low-density lipoprotein (LDL) oxidation, lipid peroxidation, and carbonyl stress that are involved in atherogenesis. We recently reported that the antihypertensive drug, hydralazine, exhibits carbonyl scavenger and antiatherogenic properties, but only moderate antioxidant activity, so that high concentrations are required for inhibiting LDL oxidation. We aimed to develop agents sharing both antioxidant and carbonyl scavenger properties. We have synthesized a new hydralazine derivative, the bisvanillyl-hydralazone (BVH). BVH strongly inhibited LDL oxidation induced by copper and by human endothelial cells (HMEC-1), and prevented the formation of macrophagic foam cells. BVH reduced both the extracellular generation of ROS (superoxide anion and hydrogen peroxide) induced by oxidized LDL (oxLDL), as well as intracellular oxidative stress and proteasome activation, NFkappaB activation, and oxLDL-mediated proinflammatory signaling. In parallel, BVH prevented the carbonyl stress induced by oxLDL on cellular proteins, and blocked the apoptotic cascade as assessed by the inhibition of Bid cleavage, cytochrome C release, and DEVDase activation. Lastly, BVH prevented atherogenesis and carbonyl stress in apoE(-/-) mice. In conclusion, BVH is the prototype of a new class of antioxidant and carbonyl scavenger agents designed for new therapeutical approaches in atherosclerosis.

Platinum-catalyzed intramolecular hydrohydrazination: evidence for alkene insertion into a Pt-N bond.

Dicationic (bpy)Pt(II) complexes were found to catalyze the intramolecular hydrohydrazination of alkenes. Reaction optimization revealed Pt(bpy)Cl(2) (10 mol %) and AgOTf (20 mol %) in DMF-d(7) to be an effective catalyst system for the conversion of substituted hydrazides to five- and six-membered N-amino lactams (N-amino = N-acetamido at 120 degrees C, N-phthalimido at 80 degrees C, (-)OTf = trifluoromethanesulfonate). Of the four possible regioisomeric products, only the product of 5-exo cyclization at the proximal nitrogen is formed, without reaction at the distal nitrogen or 6-endo cyclization. The resting states were found to be a 2:1 Pt-amidate complex (25, for N-acetamido) of the deprotonated hydrazide and a Pt-alkyl complex of the cyclized pyrrolidinone (20 for N-phthalimido). Both complexes are catalytically competent. Catalysis using 25 as the precatalyst shows no rate dependence on added acid (HOTf) or base (2,6-lutidine). The available mechanistic data are all consistent with a mechanism involving N-H activation of the hydrazide, followed by insertion of the alkene into the Pt-N bond, and finally protonation of the resulting cyclized alkyl complex by hydrazide to release the hydrohydrazination product and regenerate the active Pt-amidate catalyst.

Molecular modeling and molecular dynamics studies of hydralazine with human DNA methyltransferase 1.

DNA methyltransferases (DNMTs) are a family of enzymes that methylate DNA at the C5 position of cytosine residues, and their inhibition is a promising strategy for the treatment of various developmental and proliferative diseases, particularly cancers. In the present study, a binding model for hydralazine, with a validated homology model of human DNMT, was developed by the use of automated molecular docking and molecular dynamics simulations. The docking protocol was validated by predicting the binding mode of 2'-deoxycytidine, 5-azacytidine, and 5-aza-2'-deoxycytidine. The inhibitory activity of hydralazine toward DNMT may be rationalized at the molecular level by similar interactions within the binding pocket (e.g., by a similar pharmacophore) as established by substrate-like deoxycytidine analogues. These interactions involve a complex network of hydrogen bonds with arginine and glutamic acid residues that also play a major role in the mechanism of DNA methylation. Despite the different scaffolds of other non-nucleoside DNMT inhibitors such as procaine and procainamide, the current modeling work reveals that these drugs exhibit similar interactions within the DNMT1 binding site. These findings are valuable in guiding the rational design and virtual screening of novel DNMT inhibitors.

Coordination properties of hydralazine Schiff base Synthesis and equilibrium studies of some metal ion complexes.

In the present study, a new ligand is prepared by condensation of hydralazine (1-Hydralazinophthalazine) with 2-butanon-3-oxime. The acid-base equilibria of the schiff-base and the complex formation equilibria with the metal ions as Cu(II), Ni(II), Co(II), Cd(II), Mn(II) and Zn(II) are investigated potentiometrically. The stability constants of the complexes are determined and the concentration distribution diagrams of the complexes are evaluated. The effect of metal ion properties as atomic number, ionic radius, electronegativity and ionization potential are investigated. The isolated solid complexes are characterized by conventional chemical and physical methods. The potential coordination sites are assigned using the i.r. and (1)H NMR spectra. The structures of the isolated solid complexes are proposed on the basis of the spectral and magnetic studies.

Syntheses and in vitro evaluation of 4-(2-aminoethyl)-2(3H)-indolones and related compounds as peripheral prejunctional dopamine receptor agonists.

A series of (beta-aminoethyl)indolones and related compounds was synthesized and evaluated in vitro as peripheral prejunctional dopaminergic agonists in the field-stimulated isolated perfused rabbit ear artery. 4-[2-(Di-n-propylamino)ethyl]-7-hydroxy-2(3H)-indolone was the most potent compound (ED50 = 2 +/- 0.3 nM) tested, while the related secondary amine 24 and the des-OH derivatives 28 and 34 were only slightly less potent. 4-Methoxybenzeneethanamine and 2-methyl-3-nitrophenylacetic acid were employed as starting materials for for the synthesis of the 4-(beta-aminoethyl)indolones. The ring-opened 3-acylamino analogues 46 and 47 were prepared via nitration of the phenethylamine 43 derived from 4-methoxyphenylacetic acid. The inactive isomeric indolones 38, 39, and 41 were derived from 4-nitrobenzeneethanamine and from indolone-6-acetic acid.

Synthesis, formulation, and clinical pharmacological evaluation of hydralazine pyruvic acid hydrazone in two healthy volunteers.

Hydralazine pyruvic acid hydrazone [2-(phthalazin-1-yl hydrazono)propionic acid; 1] is a major plasma metabolite of hydralazine in humans. A number of in vitro and animal studies have suggested that this hydrazone may have cardiovascular activity and could account for the prolonged antihypertensive effect of hydralazine in humans in the absence of detectable plasma levels of the parent drug. To study this possibility, the soluble sodium salt of hydralazine pyruvic acid hydrazone (2) was synthesized, its chemical purity and stability was checked, and an intravenous formulation was prepared. Isomeric forms were identified. Doses of 0.3, 0.6, and 1.1 mumol/kg of 2 were administered intravenously to one slow and one heterozygous fast acetylator of sulfamethazine. The slow acetylator received two additional doses of 0.06 and 0.14 mumol/kg. Peak plasma levels of 1 of 18 mumol/L were attained without tachycardia or hypotension in either subject. There was no evidence of nonlinearity in kinetics over the dose range studied and clearance remained constant in both subjects (0.517 +/- 0.033 mL/min/kg in the slow acetylator and 0.744 +/- 0.058 mL/min/kg in the fast acetylator). The distribution of 1 varied unpredictably with dose, and changes were reflected in the terminal half-life (3.47-5.97 h in the slow acetylator and 2.06-5.33 h in the fast acetylator). Only traces of the acetylated metabolite of hydralazine, 3-methyl-s-triazolo[3,4-a]phthalazine (3), were detected in the plasma of the subjects, suggesting that significant metabolism via this route was unlikely. An established and specific assay for hydralazine was further modified to allow measurement of levels as low as 1 nmol/L (0.2 ng/mL).(ABSTRACT TRUNCATED AT 250 WORDS)

Determination of hydralazine and its metabolites by gas chromatography-mass spectrometry.

Metabolism of the vasodilator hydralazine was investigated by in vivo and in vitro studies. Standards to identify metabolic products were synthesized. Determination and quantification of hydralazine and its metabolites were accomplished by gas chromatography-mass spectrometry. A deuterium-labeled internal standard was used for quantification. 14C-labeled internal standards were synthesized and used to demonstrate recoveries from the biological samples.