Synthesis and biological evaluation of 1,4-benzodiazepin-2-ones with antitrypanosomal activity

A library of 1,4-benzodiazepines has been synthesized and evaluated against Trypanosoma brucei, a causative parasite of Human African trypanosomiasis. Benzodiazepines possessing a P2- transporter motif were found to have MIC values as low as 0.78 μM.     

Copper-psychoactive drug complexes: a voltammetric approach to complexation by 1,4-benzodiazepines

Copper complexation by the 1,4-benzodiazepines medazepam, diazepam, flurazepam, nitrazepam, and clonazepam was investigated using differential pulse polarography and cyclic voltammetry at a mercury electrode in 0.10 M KNO3 and pH 7.0 +/- 0.1. Because the 1,4-benzodiazepines are easily reduced at a mercury electrode through the two-electron reduction of the 4,5-azomethine functional group, copper reduction, as well as that of the ligands, was analyzed under varying experimental conditions. In most situations adsorption phenomena occurred and their influence on voltammetric signals had to be carefully analyzed. The voltammetric behavior was then interpreted in terms of complex formation. The results showed that all benzodiazepines can act as ligands toward copper(II) ions, forming 1:1 and 1:2 complexes with similar stabilities. The stoichiometric acidity constants of the benzodiazepines under study were also determined by potentiometric titration in water-ethanol medium and 0.10 M KNO3 and then extrapolated to 0% concentration of ethanol.     

1,4-Benzodiazepine peripheral cholecystokinin (CCK-A) receptor agonists

A series of 1,4-benzodiazepines, N-1-substituted with an N-isopropyl-N-phenylacetamide moiety, was synthesized and screened for CCK-A agonist activity. In vitro agonist activity on isolated guinea pig gallbladder along with in vivo induction of satiety following intraperitoneal administration in a rat feeding assay was demonstrated.     

Identification of cytotoxic, T-cell-selective 1,4-benzodiazepine-2,5-diones

A family of 1,4-benzodiazepine-2,5-diones (BZDs) has been synthesized and evaluated against transformed B- and T-cells for lymphotoxic members. A large aromatic group on the C3 position is critical for cytotoxicity. When the C3 moiety contains an electron-rich heterocycle, the resulting BZDs have sub-micromolar potency and are selective for T-cells. Cell death is consistent with apoptosis and does not result from inhibition of the mitochondrial F(o)F1-ATPase, which is the molecular target of recently reported cytotoxic 1,4-benzodiazepines. Collectively, these studies begin to characterize some of the structural elements required for the activity of a novel family of T-cell-selective lymphotoxic agents.     

Investigation into mechanisms mediating the inhibitory effect of 1,4-benzodiazepines on mast cells by gene expression profiling

AimsThis study aims to identify by a molecular genetic approach potential targets in mast cells at which 1,4-benzodiazepines may cause their inhibitory effect on mast cell activity.Main methodsGene expression analyses with microarray gene chip and/or quantitative PCR were performed using 1,4-benzodiazepine-treated human mast cell leukemia HMC-1.2 cells, promyelocytic leukemia HL-60 cells and human mast cells from healthy volunteers and patients with mast cell activation disease (MCAD). Pathway analysis was applied to search for enriched biological functions and canonical pathways within differentially regulated genes.Key findingsBoth neoplastic and normal human mast cells express several GABA_A receptor subunits at the mRNA level. In mast cells from MCAD patients expression of some GABA_A receptor subunits and expression of the translocator protein TSPO are increased compared with those from healthy controls. Expression of the protein tyrosine kinases Lyn, Fgr and Yes1 was increased in HMC-1.2 cells as compared with the ontogenetically related HL60 cells. Differences in gene regulation in HMC-1.2 cells after treatment with the 1,4-benzodiazepines clonazepam, flunitrazepam and 4-chlorodiazepam suggested that signaling and gene expression induced by clonazepam was similar to that of flunitrazepam but different from that of 4-chlorodiazepam. This conclusion is supported by the results of the pathway analysis.SignificanceA novel type of GABA_A receptors on mast cells appears to be involved in the inhibition of mast cell activity by 1,4-benzodiazepines. These receptors seem to be composed without γ subunits suggesting unique pharmacological properties. An action at Src-kinases, or at TSPO located in the plasma membrane may also be involved.     

Pyrrolo(1,4)benzodiazepine antitumor antibiotics. In vitro interaction of anthramycin, sibiromycin and tomaymycin with DNA using specifically radiolabelled molecules.

Anthramycin, tomaymycin and sibiromycin are pyrrolo(1,4)benzodiazepine antitumor antibiotics. These compounds react with DNA and other guanine-containing polydeoxynucleotides to form covalently bound antibiotic - polydeoxynucleotide complexes. Experiments utilizing radiolabelled antibiotics have led to the following conclusions: 1. Sibiromycin reacts much faster than either anthramycin or tomaymycin with DNA. 2. At saturation binding the final antibiotic to base ratios for sibiromycin, anthramycin and tomaymycin are 1 : 8.8,1: 12.9, and 1 : 18.2, respectively. 3. No reaction with RNA or protein occurs with the pyrrolo(1,4)benzodiazepine antibiotics. 4. Sibiromycin effectively competes for the same DNA binding sites as anthramycin and tomaymycin; however, there is only partial overlap for the same binding sites between anthramycin and tomaymycin. 5. Whereas all three pyrrolo(1,4)benzodiazepine antibiotic-DNA complexes are relatively stable to alkaline conditions, their stability under acidic conditions increases in the order tomaymycin, anthramycin and sibiromycin. 6. No loss of non-exchangeable hydrogens in either the pyrrol ring or the side chains of these antibiotics occurs upon formation of their complexes with DNA. 7. Unchanged antibiotic has been demonstrated to be released upon acid treatment of the anthramycin-DNA and tomaymycin-DNA complexes. 8. A Schiff base linkage between the antibiotics and DNA has been eliminated. The comparative reactivity of the three antibiotics towards DNA and the stability of their DNA complexes is discussed in relation to their structures. A working hypothesis for the formation of the antibiotic-DNA covalent complexes is proposed based upon the available information.     

Synthesis and DNA-binding affinity of A-C8/C-C2 alkoxyamido-linked pyrrolo[2,1-c][1,4]benzodiazepine dimers

The synthesis of new A-C8/C-C2 alkoxyamido-linked pyrrolo[2,1-c][1,4]-benzodiazepine dimers have been described in this report. These dimers exhibit significant DNA-binding ability with moderate anticancer activity.     

Clozapine derived 2,3-dihydro-1H-1,4- and 1,5-benzodiazepines with D4 receptor selectivity: synthesis and biological testing

Novel 4-arylpiperazin-1-yl-substituted 2,3-dihydro-1H-1,4- and 1H-1,5-benzodiazepines and their aza-analogues were synthesized as debenzoclozapine derivatives for evaluation as potential D4-ligands. While Ki values of some of the title compounds came within the range of clozapine, they showed an impressively greater selectivity over other dopamine receptor subtypes, especially D2. For the most promising compounds, intrinsic activity and binding properties to serotonin 5-HT1A and 5-HT2 were also determined.     

Synthesis, DNA binding, and cytotoxicity studies of pyrrolo[2,1-c][1,4]benzodiazepine-anthraquinone conjugates

A series of pyrrolo[2,1-c][1,4]benzodiazepine-anthraquinone conjugates have been prepared and evaluated for their DNA binding ability as well as anticancer activity. Some of these molecules have shown significant anticancer activity in a number of cancer cell lines.     

Synthesis of C-8 alkylamino substituted pyrrolo[2,1-c][1,4]benzodiazepines as potential anti-cancer agents

The design and facile synthesis of C-8 alkylamino substituted pyrrolo[2,1-c][1,4]benzodiazepines is described. These have been prepared by linking the amines at C-8 position with propane spacer to improve solubility in water, and their in vitro cytotoxicity studies have been carried out.     

Selective affinity of 1-N-trifluoroethyl benzoidiazepines for cerebellar type 1 receptor sites

In binding studies with rat brain membranes, 1,4-benzodiazepines containing a trifluoroethyl moeity at the 1-N position, including halazepam and quazepam, had significantly higher affinities for binding sites in cerebellum than in cortex. This selectivity for cerebellar sites is not a property of benzodiazepines without the trifluoroethyl moiety, but is similar to that seen with the triazolopyridazines. Since halazepam and quazepam, like the triazolopyridazines, have behavioral effects in animals at doses much lower than those that cause ataxia, it is tempting to attribute this separation of pharmacologic activities to differential activity at subpopulations of benzodiazepine receptors. Further work is necessary to clarify this possibility.     

Tofizopam enhances the action of diazepam against tremor and convulsions

Tofizopam, an anxiolytic 3,4-benzodiazepine, increases the affinity of benzodiazepine receptors for 1,4-benzodiazepines. In this study we investigated whether this increased affinity of the receptors alters the sensitivity of mice to tremor and to convulsions. Convulsions induced by harmane were not affected by tofizopam (50-300 mg/kg), but diazepam (15 mg/kg) increased the ED50 of harmane from 9.9 to 25.1 mg/kg. Tofizopam did not alter the threshold for electroshock-induced convulsions, while a dose of 10 mg/kg diazepam protected mice from convulsions. Low doses of tofizopam (12.5-25 mg/kg) sensitized mice to the tremorogenic effect of harmaline. Diazepam inhibited tremor: the ED50 of harmaline increased by 153% after 50 mg/kg of diazepam. In contrast to 1,4-benzodiazepines, tofizopam has no anticonvulsive effect. It sensitises mice to the tremor induced by harmaline. In combination with diazepam, however, tofizopam enhanced the anticonvulsive and antitremorogenic actions of this 1,4-benzodiazepine by 12-65%. This effect probably results from a tofizopam-induced increase in the occupation of benzodiazepine receptors.     

Comparative analysis of the pharmacokinetics of N1-unsubstituted derivatives of 1,4-benzodiazepine

Parameters of 14C-7-bromo-5-phenyl-1,2-dihydro-3H-1,4-benzodiazepine-2 and its main metabolite distribution in the blood plasma and brain of mice were compared with phenazepam and nordiazepam distribution. Constant ratio of blood plasma 14C-7-bromo-5-phenyl-1,2-dihydro-3A-1,4-benzodiazepine-2, its 3-hydroxy metabolite and other derivatives' level to brain level was noted vs their changing content in the mentioned test objects. Characteristic peculiarities of the distribution of initial 1,4-benzodiazepines and their metabolites and its predictive value are discussed.     

Solid-phase synthesis of pyrrolo[2,1-c][1,4]benzodiazepine-5,11-diones

The solid-phase synthesis of biologically important pyrrolo[2,1-c][1,4]benzodiazepine-5,11-diones using Wang resin through amide formation and reductive cyclization procedures is described. Further, N10-substituents have been introduced in the final products and these have been cleaved from the solid support in good yields.     

Stereoselective effect of phenprocoumon enantiomers on the binding of benzodiazepines to human serum albumin.

The effect of phenprocoumon enantiomers on the stereoselective binding of 3-substituted 1,4-benzodiazepines to human serum albumin (HSA) was studied by chromatography on HSA-Sepharose column. (S)-Phenprocoumon exerts stereoselective allosteric interaction on the binding of benzodiazepines. The structural requirements of enhanced stereoselectivities are similar to those found previously with (S)-warfarin.     

Identification of a potent and selective oxytocin antagonist, from screening a fully encoded differential release combinatorial chemical library

A library of 1,296 1,4-benzodiazepines was prepared on 160 microM Tentagel beads. Compounds are attached to the beads using orthogonally cleavable linkers. The library was first screened as pools of 30 beads where 50% of the material is released and screened. GW405212X, a selective oxytocin antagonist, was identified by picking single beads from active pools.     

Solid-phase synthesis of new pyrrolobenzodiazepine-chalcone conjugates: DNA-binding affinity and anticancer activity

A new class of C8-linked pyrrolo[2,1-c][1,4]benzodiazepine-chalcone conjugates have been prepared by employing a solid-phase synthetic protocol. In this strategy an intramolecular aza-Wittig reductive cyclization approach has been utilized. Interestingly, some of these molecules have shown enhanced DNA-binding affinity and promising anticancer activity on a large number of human cancer cell lines.     

Mass-spectrometric analysis of 2-aminobenzophenone derivatives and their metabolites

Mass-spectrometry analysis was carried out for 2-aminobenzophenone, its halogen derivatives and metabolites formed in the rat organism. The characteristic fragmentation patterns were outlined for the products arising on hydroxylation of the above compounds. The structural specificity in the oxidation of 2-aminobenzophenones was found to be different from that predominant in hydroxylation of phenyl (o-chlorophenyl) ring of 1,4-benzodiazepines which give on hydrolysis the respective benzophenones.     

A novel approach to the synthesis of cytotoxic C2-C3 unsaturated pyrrolo[2,1-c]benzodiazepines (PBDs) with conjugated acrylyl C2-substituents

A concise synthesis of three novel C2-C3 unsaturated pyrrolo[2,1-c][1,4]benzodiazepine analogues (18-20) containing conjugated acrylyl C2-substituents is reported that utilises Heck coupling to install the C2-acrylyl side chains. These analogues possess significant cytotoxicity according to the NCI 60-cell line screen with 18 surpassing anthramycin (1) in potency.     

Synthesis and anti-HIV activity of 1,3,4,5-tetrahydro-2H-1,4-benzodiazepin-2-one (TBO) derivatives. Truncated 4,5,6,7-tetrahydro-5-methylimidazo[4,5,1-jk][1,4]benzodiazepin-2( 1H)-on es (TIBO) analogues

4,5,6,7-Tetrahydro-5-methylimidazo[4,5,1-jk][1,4]benzodiazepin-2(1 H)-ones (TIBO), 1, have been shown to significantly inhibit HIV-1 replication, as reported in detail in our prior publications. Since our earlier reports, we have modified the TIBO structures 1 by removing the 5-membered ring of 1, generating 1,3,4,5-tetrahydro-2H-1,4-benzodiazepin-2-ones (TBO), 4, a bicyclic series of compounds. Although compounds 4 possess modest activity when compared to TIBO analogues 1, they clearly demonstrated significant anti-HIV-1 activity.