Synergistic anti-leukemic effects of CK2 inhibitors and pentabromobenzylisothioureas in vitro

BACKGROUND

Casein kinase-2 (CK2) inhibitors and pentabromobenzylisothioureas are promising anti-leukemic agents for treatment, both alone and in combination. In this study, we examined pro-apoptotic and cytostatic effects of three CK2 inhibitors: one known, 2-dimethylamino-4,5,6,7-tetrabromo-1H-benzimidazole (DMAT) and two new: 2-(4-methylpiperazin-1-yl)-4,5,6,7-tetrabromo-1H-benzimidazole (MPT) and 2-aminoethyleneamino-4,5,6,7-tetrabromo-1H-benzimidazole (AEAT), as well as of certain S-2,3,4,5,6-pentabromobenzylisothiouronium bromides: ZKK-3, ZKK-9, ZKK-13, against the human acute myelogenous leukemia cell line (KG-1). Cells were treated with CK2 inhibitors alone and in combination with the pentabromobenzylisothioureas.

MATERIALS AND METHODS

Evaluation of synergistic and pro-apoptotic effects, mitochondrial membrane potential (ΔΨm) assay, poly(ADP-ribose) polymerase (PARP) cleavage assay, and cell-cycle progression of KG-1 cells were carried out using the flow cytometric technique and fluorescent microscopic analysis. Western blots were used for analysis of B-cell lymphoma-2 (BCL-2) family proteins in whole-cell extracts.

RESULTS

The tested CK2 inhibitors DMAT, MPT, AEAT exhibited synergistic proapoptotic effect in combination with ZKK-3, ZKK-9 and ZKK-13. The agents revealed different pro-apoptotic efficacies against leukemia cell line KG-1. The highest apoptotic activity of the tested compounds was exhibited by AEAT.

CONCLUSION

Combination of CK2 inhibitors and pentabromobenzylisothioureas-induced synergistic anti-leukemic effects against KG-1 acute myelogenous leukemia cells in vitro.

Does molecular docking reveal alternative chemopreventive mechanism of activation of oxidoreductase by sulforaphane isothiocyanates?

Isothiocyanates (ITC) are well-known chemopreventive agents extracted from vegetables. This activity results from the activation of human oxidoreductase. In this letter, the uncompetitive activatory mechanism of ITC was investigated using docking and molecular dynamics simulations. This indicates that NAD(P)H:quinone oxidoreductase can efficiently improve enzyme-substrate recognition within the catalytic site if the ITC activator supports the interaction in the uncompetitive binding site.

Intrinsic activity and comparative molecular dynamics of buspirone analogues at the 5-HT1A receptors

In CNS, the 5-hydroxytryptamine(1A) (5-HT(1A)) receptors exist in two different populations with different behavioural and physiological effects: (1) somatodendritic autoreceptors located pre-synaptically of 5-HT containing neurons and (2) receptors located post-synaptic to 5-HT containing neurons. Clinical studies have shown that 5-HT(1A) partial agonists have anxiolytic properties, while antagonists of pre-synaptical autoreceptors shorten the onset time of selective serotonin reuptake inhibitors (SSRIs). In the present study, the pre- and post-synaptic activity of structural analogues of buspirone was evaluated in animal models. A three dimensional model of the 5-HT(1A) receptor was used to study their interaction modes and helical displacements upon receptor binding. The predicted receptor-ligand interactions indicated similarities in the receptor binding modes for all buspirone analogues, and no clear relationship between receptor contact residues and activity at pre- and post-synaptic receptors. Comparative molecular dynamics (MD) simulations for 650ps indicated that pre-synaptic antagonistic behaviour is connected to large displacements of transmembrane helix (TMH) 7 upon binding, while pre-synaptic agonistic behaviour is connected to large displacements of TMH2 and small displacements of TMH7. Post-synaptic partial agonist behaviour is connected to large displacements of TMH4 and TMH5 upon binding, while post-synaptic antagonists only slightly displace these helices.

Molecular dynamics of 5-HT1A and 5-HT2A serotonin receptors with methylated buspirone analogues

In the present study experimentally determined ligand selectivity of three methylated buspirone analogues (denoted as MM2, MM5 and P55) towards 5-HT1A and 5-HT2A serotonin receptors was theoretically investigated on a molecular level. The relationships between the ligand structure and 5-HT1A and 5-HT2A receptor affinities were studied and the results were found to be in agreement with the available site-directed mutagenesis and binding affinity data. Molecular dynamics (MD) simulations of ligand-receptor complexes were performed for each investigated analogue, docked twice into the central cavity of 5-HT1A/5-HT2A, each time in a different orientation. Present results were compared with our previous theoretical results, obtained for buspirone and its non-methylated analogues. It was found that due to the presence of the methyl group in the piperazine ring the ligand position alters and the structure of the ligand-receptor complex is modified. Further, the positions of derivatives with pyrimidinyl aromatic moiety and quinolinyl moiety are significantly different at the 5-HT2A receptor. Thus, methylation of such derivatives alters the 3D structures of ligand-receptor complexes in different ways. The ligand-induced changes of the receptor structures were also analysed. The obtained results suggest, that helical domains of both receptors have different dynamical behaviour. Moreover, both location and topography of putative binding sites for buspirone analogues are different at 5-HT1A and 5-HT2A receptors.

New chemical structures of hypolipidemic and antiplatelet activity

Elevated lipid level is supposed to be one of the main risk factors of atherosclerosis and subsequent cardiovascular disease (and is connected to mortality). Therefore, lipid lowering is one of the major targets in cardiovascular disease treatment and prevention. Also, blood platelets play a pivotal role in the development of atherosclerosis and fatal thrombus formation in the course of coronary heart disease. Therefore, there is a great necessity to acquire drugs inhibiting platelet aggregation and clot generation. The present paper reviews new chemical structures in development for the treatment and prevention of hyperlipidemia, atherosclerosis, and subsequent cardiovascular disease. The authors' recent results are also reported regarding synthesis of a new group of a-asarone analogs. These compounds were identified as an original class of agents exhibiting hypolipidemic and antiplatelet (mice, rats) activities. Although the mechanism of the compounds' pharmacological activity has not been identified, quantum-mechanical calculations allowed structural requirements to be described that correspond to the activity (a hypothetical pseudoreceptor structure). Since it is known that asarone and its derivatives may exhibit genotoxicity, calculations were carried out to identify derivatives of possibly low genotoxic activity.

Enantioselectivity of 3-amino-2-oxazolidinone derivatives with potential psychotropic activity on cellulose tris(4-methylbenzoate) chiral selector

The behavior of a series of 3-amino-2-oxazolidinone derivatives with a potential hypnotic activity on achiral (octadecylsilane) and chiral (cellulose tris(4-methylbenzoate)) stationary phases was examined. The compounds differed in the composition of a substituted aromatic ring containing different substituents in different positions. It was possible to resolve all the compounds with selectivity 1.11 < or = alpha < or = 2.74. The enantiodifferentiating power of substituents was correlated to their electron donating ability and position in the aromatic ring.

Molecular dynamics of buspirone analogues interacting with the 5-HT1A and 5-HT2A serotonin receptors

Three-dimensional (3-D) models of the human serotonin 5-HT1A and 5-HT2A receptors were constructed, energy refined, and used to study the interactions with a series of buspirone analogues. For both receptors, the calculations showed that the main interactions of the ligand imide moieties were with amino acids in transmembrane helix (TMH) 2 and 7, while the main interactions of the ligand aromatic moieties were with amino acids in TMH5, 6 and 7. Differences in binding site architecture in the region of highly conserved serine and tyrosine residues in TMH7 gave slightly different binding modes of the buspirone analogues at the 5-HT1A and 5-HT2A receptors. Molecular dynamics simulations of receptor-ligand interactions indicated that the buspirone analogues did not alter the interhelical hydrogen bonding patterns upon binding to the 5-HT2A receptor, while interhelical hydrogen bonds were broken and others were formed upon ligand binding to the 5-HT1A receptor. The ligand-induced changes in interhelical hydrogen bonding patterns of the 5-HT1A receptor were followed by rigid body movements of TMH2, 4 and 6 relative to each other and to the other TMHs, which may reflect the structural conversion into an active receptor structure.

Theoretical models of interactions between buspirone analogues and 5-HT1A and 5-HT2A serotonin receptor subtypes

In present study the structure-selectivity relationship of buspirone and six of its analogues towards 5-HT1A and 5-HT2A serotonin receptors was investigated on molecular level. Molecular mechanics energy minimisation and advanced molecular dynamics (MD) simulations allowed us to perform a dynamic structural analysis of transmembrane helical domains of the human 5-HT1A and 5-HT2A receptors and investigate the ligand-induced changes of the entire structure of the ligand-receptor complex. The obtained results suggest, that helical and extracellular domains of both receptors have different topography of the putative binding sites and also different dynamical behaviour. The results of this study are consistent with experimental site-directed mutagenesis data and binding affinities of examined ligands towards both serotonin receptors.

Synthesis and hypolipidemic and antiplatelet activities of alpha-asarone isomers in humans (in vitro), mice (in vivo), and rats (in vivo)

A series of alpha-asarone isomers was synthesized and investigated for their hypolipidemic and antiplatelet activity. Considering the hypolipidemic activity in rats at a dose of 80 mg/kg/day, some isomers were more potent than clofibrate at 150 mg/kg. Compound 3 was one of the most active agents elevating the HDL cholesterol level by 56% and lowering the LDL cholesterol level by 46.8% in rats after 7 days of administration. The activities of the platelet aggregation test in vitro were significant but lower than those of the reference substances (indomethacine and acetylsalicylic acid). In the pulmonary thromboembolic in vivo test in mice, two compounds (alpha-asarone (6) and compound 4) produced significant antithrombotic effects at 100 mg/kg, namely 44% and 52% protection against lung microembolia, respectively. alpha-Asarone derivatives form a new group of potential hypolipidemic and/or antithrombotic agents. The compounds 3, 4, and 6 may serve as lead substances whose structural modifications may result in original drugs.

Ligand-5-HT1A receptor interaction

In the present paper the general structure and pharmacophore of some 5-HT1A receptor ligands are described. For several compounds (approximately 15) the intrinsic activity in lower lip retraction (postsynaptic, rat) and hypothermia (presynaptic, mice) tests was determined. For the identified functional presynaptic agonists and antagonists the influence on the brain serotonin level was examined. No direct correlation between the functional intrinsic activity and the influence on the level was observed. Molecular modelling revealed the possibility of the existence of different binding sites for different examined compounds.

Enantioselective separation of 1,4-disubstituted piperazine derivatives on two cellulose chiralcel OD and OJ and one amylose chiralpak AD chiral selectors

A series of 1,4-disubstituted piperazine derivatives with hypnotic activity were examined on three polysaccharide-based chiral stationary phases, namely, Chiracel OD, Chiracel OJ and Chiralpak AD. It was possible to resolve all the compounds on all the phases examined (1.13 </= alpha </= 3.54). Cellulose tris(4-methylbenzoate) (Chiracel OJ) exhibited remarkable differences in the selectivity of enantiomeric resolution as compared to cellulose tris(3, 5-dimethylphenylcarbamate)-Chiracel OD and amylose tris(3, 5-dimethylphenylcarbamate)-Chiralpak AD. The differences in selectivity towards particular homologs on these phases could be explained in terms of lipophilicity and steric factors. Copyright 1999 Wiley-Liss, Inc.

13C cross-polarization magic angle spinning NMR and gauge-independent atomic orbital, coupled Hartree-Fock calculations of buspirone analogues. Part 2. Hydrochlorides and perchlorates of 1-arylpiperazine-4-alkylimides

13C cross-polarization (CP) magic angle spinning (MAS) solid state NMR spectra of hydrochlorides and perchlorates of buspirone analogues (2-5) were recorded. In the spectra for each compound, one set of signals appeared, in agreement with single crystal X-ray diffraction data indicating the presence of one molecule per crystal unit. The resonances of 2-5 hydrochlorides were assigned by comparison with the solution chemical shifts. For perchlorate 2b and diperchlorate 2c, the reasonable assignment of signals was made with the aid of the theoretical studies. Ab initio calculations of the carbon shieldings were performed by means of the GIAO-CHF method for two model systems: perchlorate and diperchlorate of quinoline-(N-methyl)piperazine. As no remarkable differences between carbon chemical shifts of hydrochlorides 3-5 in solid state and in solution were observed, it was concluded that in solution these compounds adopted the same conformation as in the solid state.

Application of chiral chromatographic parameters in quantitative structure-activity relationship analysis of homologous malathion derivatives

The conditions of the chiral resolution of the racemic malathion O,O-di-n-alkyl derivatives on cellulose tris(3,5-dimethylphenylcarbamate) are described. Quantitative relationships between chromatographic parameters obtained on chiral and achiral stationary phases and acute toxicity of the compounds towards house fly are derived and discussed.

13C CP (cross-polarization) MAS (magic angle spinning) NMR and GIAO-CHF calculations of buspirone analogues. Part 1. 3a,4,7,7a-Tetrahydro-2-[4-[4-(2-quinolinyl)-1-piperazinyl]butyl ]-4,7-ethane-1H-isoindole-1,3(2H)-dione hydrochloride and hydrobromide

13C CP (cross-polarization) MAS (magic angle spinning) solid state NMR spectra of buspirone analogue 3a,4,7,7a-tetrahydro-2-[4-[4-(2-quinolinyl)-1-piperazinyl]butyl]-4,7-eth ane-1H-isoindole-1,3(2H)-dione were recorded. In the spectra of hydrochloride and hydrobromide, two sets of signals appeared, in agreement with single crystal X-ray diffraction data indicating that in each of the salts two independent cations were present in the crystal unit. The largest shielding differences of 3.2-4.6 ppm between two sets of signals were found for quinoline aromatic carbons C3 and C2. Ab initio calculations of the carbon and nitrogen shielding constants were performed with the use of the GIAO-CHF method for structural fragments: N-butylsuccinimide, quinoline-(N-methyl) piperazine hydrochloride and hydrobromide. Linear correlations between theoretical and solid state results were obtained, thus enabling a reasonable assignment of carbon resonances of the conformations present in the solid state. Due to the fast dynamics in solution, the carbon chemical shifts corresponded to the averaged values of the forms present in the solid state.

The ligand-binding site of buspirone analogues at the 5-HT1A receptor

A three-dimensional model of the 5-HT1A receptor in man was constructed by molecular-modelling techniques and used to study the molecular interactions of a series of buspirone analogues with the 5-HT1A receptor by molecular-mechanical-energy minimization and molecular-dynamics simulations. The receptor has seven trans-membrane alpha helices (TMHs) organized according to the electron-density-projection map of visual rhodopsin, and includes all loops between TMHs and the N- and C-terminal parts. The best fit between the buspirone analogues and the receptor model was obtained with the quinolinyl part of the ligand molecules interacting with amino acids in TMH6, the imide group interacting with amino acids in TMH2, TMH3 and TMH7, and the carbonyl groups hydrogen-bonded with Ser86 and Ser393. The ligand-binding rank order deduced from the experimentally determined inhibition constant was reproduced by calculation of receptor-binding energies of the buspirone analogues. The models suggest that steric hindrance and repulsive forces between the receptor and the imide group of the buspirone analogues are the most important determinants of ligand-binding affinity for discriminating between these ligands.

Conformational flexibility of serotonin1A receptor ligands from crystallographic data. Updated model of the receptor pharmacophore

Preparation and affinity to 5-HT1A and 5-HT2A receptors of new buspirone analogues 7-17 are reported. The compounds possess high to low affinity to 5-HT1A and moderate to low to 5-HT2A receptors. The crystal structures have been determined for compounds 11, 12, 13, and 14. For low affinity ligand (15) of 5-HT1A receptor conformational analysis was performed and compared with similar analyses performed for know high (buspirone 1) and very high (WY-48,723 2) affinity ligands of the receptor. Structure-activity relationship is discussed for the affinity to 5-HT1A receptor. A three-point pharmacophore explaining interactions of buspirone-like molecules with the receptor binding site is proposed.

Some derivatives of 3-amino-2-oxazolidinone influencing neurotransmission of dopamine and serotonin

The influence of 3-amino-2-oxazolidinone derivatives 1-9 on dopaminergic and serotoninergic neurotransmission was tested. It was found that all tested compounds exhibited modulating activity on one (or both) of the neurotransmissions, the effect being dependent on the aromatic ring substituent.

Buspirone analogues as ligands of the 5-HT1A receptor. II: Capacity factors as chromatographic parameter of lipophilicity evaluation in a series of 5-HT1A and 5-HT2A receptor ligands

The lipophilicity of a series of buspirone related agents was studied by means of reversed-phase HPLC using an octadecylsilane stationary phase a mixture of aqueous solution of sodium phosphate and methanol as a mobile phase. Comparison of the measured capacity factors with log P values has shown very good correlations with regression correlation coefficients in the range of 0.994-0.996.

Structure-activity relationship in a series of new 1-(2-pyrimidinyl)piperazine derivatives with hypnotic activity

Preparation, biological properties and QSAR of new derivatives of 1-[4-(2-pyrimidinyl)-1-piperazinyl]-1, 3-butandione (11-13, and 15-18) and 3-[4-(2-pirimidinyl)-1-piperazinyl]-3-oxopropanoate (20-22) exhibiting hypnotic activity in mice are reported. The best therapeutic indices (TI = LD50/ED50) 4.7 and 9.4 for po and ip administration, respectively, were found for 1-[4-(2-pyrimidinyl)-1-piperazinyl]-2-n-pentyl-1,3-butandione (15). QSAR studies showed that the biological activity grows initially with an increase in lipophilicity to drop dramatically for log P > 2.5.

Effects of a new oxazolidinone derivative AS-8 on serotonin metabolism in the brains of mouse, rat and chick

The effect of 5-morpholinemethyl-3-(4-chlorobenzylideneamino)-2-oxazolidin one (AS-8), a potential antidepressant drug, was tested on 5-hydroxytryptamine (5-HT) metabolism in the brains of rat, mouse and chick. The ip administration of AS-8 (25-500 mg/kg) did not modify the cerebral 5-HT level, but significantly increased the level of 5-hydroxyindoleacetic acid (5-HIAA) the main 5-HT metabolite. In animals receiving pargyline (a MAO-A inhibitor which blocks 5-HT catabolism), AS-8 markedly enhanced 5-HT accumulation in the brains of rats and mice, but not chicks. It is concluded that AS-8 is capable of stimulating of 5-HT synthesis at least in the mammalian brain.

Buspirone analogues as ligands of the 5-HT1A receptor. 1. The molecular structure of buspirone and its two analogues

An interdisciplinary (X-ray, 1H and 13C NMR, IR, and theoretical quantum mechanical) study on the potent 5-HT1A receptor ligand buspirone (1) and its two structural analogues, mesmar (4,4-dimethyl-1-[4-[4-(2-quinolinyl)-1-piperazinyl]butyl]-2,6- piperidinedione) (2) and kaspar (8-[4-[4-(2-quinolinyl)-1-piperazinyl]butyl]-8-azaspiro[4.5]decane - 7,9-dione) (3), has been reported. The results have shown that buspirone-like molecules should appear in an extended rod-shape form, possessing several potential interaction sites with the receptor.

Some analogues of 1,4-disubstituted piperazines as hypnotic and sedative agents

Preparation, analytical data, and biological properties such as acute toxicity, influence on spontaneous and amphetamine induced locomotor activity, hypnotic activity, influence on hexobarbital narcosis and anticonvulsant activity of new analogues of pyrimidyl piperazines--ethyl 3-[4-(2-pyrimidyl)-1-piperazinyl]-3-oxopropanoate (4), 1-[4-(2-pyrimidyl)-1-piperazinyl]-1,3-butandione (5), ethyl 3-[4-(2-pyrimidyl)-1-piperazinyl]butanoate (6) and 1-[4-(2-pyrimidyl)-1-piperazinyl]-2-acetyl-1-hexanone (7)--are reported.