Dibenzazepine-linked isoxazoles: New and potent class of α-glucosidase inhibitors.

α-Glucosidase inhibition is a valid approach for controlling hyperglycemia in diabetes. In the current study, new molecules as a hybrid of isoxazole and dibenzazepine scaffolds were designed, based on their literature as antidiabetic agents. For this, a series of dibenzazepine-linked isoxazoles (33-54) was prepared using Nitrile oxide-Alkyne cycloaddition (NOAC) reaction, and evaluated for their α-glucosidase inhibitory activities to explore new hits for treatment of diabetes. Most of the compounds showed potent inhibitory potency against α-glucosidase (EC 3.2.1.20) enzyme (IC50 = 35.62 ± 1.48 to 333.30 ± 1.67 µM) using acarbose as a reference drug (IC50 = 875.75 ± 2.08 µM). Structure-activity relationship, kinetics and molecular docking studies of active isoxazoles were also determined to study enzyme-inhibitor interactions. Compounds 33, 40, 41, 46, 48-50, and 54 showed binding interactions with critical amino acid residues of α-glucosidase enzyme, such as Lys156, Ser157, Asp242, and Gln353.

Neurotoxicity induced by antiepileptic drugs in cultured hippocampal neurons: a comparative study between carbamazepine, oxcarbazepine, and two new putative antiepileptic drugs, BIA 2-024 and BIA 2-093.

PURPOSE: Newly designed antiepileptic drugs (AEDs) are being evaluated for their efficacy in preventing seizures and for their toxic profiles. We investigated and compared the toxic effects of two dibenz[b,f]azepine derivatives with anticonvulsant activity, 10,11-dihydro-10-hydroxyimino-5H-dibenz[b,f]azepine-5-carboxamide (BIA2-024) and (S)-(-)-10-acetoxy-10,11-dihydro-5H-dibenz[b,f] azepine-5-carboxamide (BIA2-093), with the structurally related compounds carbamazepine (CBZ) and oxcarbazepine (OXC), both in current use for the treatment of epilepsy. METHODS: Primary rat hippocampal neurons were used to evaluate neuronal morphology and biochemical changes induced by the AEDs used in this study. Immunocytochemical staining against MAP-2 was used to evaluate neuronal morphology. Reactive oxygen species (ROS) and changes in mitochondrial membrane potential (Psim) were measured by fluorescence techniques. Intracellular adenosine triphosphate (ATP) levels were quantified by high-performance liquid chromatography (HPLC). RESULTS: Hippocampal neurons treated for 24 h with CBZ or OXC (300 microM) showed degeneration and swelling of neurites, but this effect was not observed in neurons treated with BIA 2-024 or BIA 2-093 (300 microM). ROS production also was increased in neurons treated with OXC, but not in neurons treated with the other AEDs. ATP levels were significantly decreased only in neurons treated with OXC, although the energy charge was not altered. Furthermore, OXC led to a decrease of Psim. CONCLUSIONS: In all parameters assayed, OXC was more toxic than the other AEDs used. Because the new putative AEDs have previously been shown to have an efficacy in preventing seizures similar to that of CBZ and OXC, and are less toxic to neuronal cells, they may be considered as alternatives to the current available therapies for the treatment of epilepsy.

Neurotoxic/neuroprotective profile of carbamazepine, oxcarbazepine and two new putative antiepileptic drugs, BIA 2-093 and BIA 2-024.

We investigated and compared the toxicity profile, as well as possible neuroprotective effects, of some antiepileptic drugs in cultured rat hippocampal neurons. We used two novel carbamazepine derivatives, (S)-(-)-10-acetoxy-10,11-dihydro-5H-dibenz[b, f]azepine-5-carboxamide (BIA 2-093) and 10, 11-dihydro-10-hydroxyimino-5H-dibenz[b,f]azepine-5-carboxamide (BIA 2-024), and compared their effects with the established compounds carbamazepine and oxcarbazepine. The assessment of neuronal injury was made by using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl (MTT) assay, as well as by analysing morphology and nuclear chromatin condensation (propidium iodide staining), after hippocampal neurons were exposed to the drugs for 24 h. The putative antiepileptic drugs, BIA 2-093 or BIA 2-024 (at 300 microM), only slightly decreased MTT reduction, whereas carbamazepine or oxcarbazepine were much more toxic at lower concentrations. Treatment with the antiepileptic drugs caused nuclear chromatin condensation in some neurons, which is characteristic of apoptosis, and increased the activity of caspase-3-like enzymes, mainly in neurons treated with carbamazepine and oxcarbazepine. The toxic effect caused by carbamazepine was not mediated by N-methyl-D-aspartate (NMDA) or by alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionate (AMPA) receptors. Moreover, the antiepileptic drugs failed to protect hippocampal neurons from the toxicity caused by kainate, veratridine, or ischaemia-like conditions.

Ancillary approaches to toxicokinetic evaluations.

The principal objective of toxicokinetic studies is to assess systemic exposure of the toxicity species to test compound during nonclinical toxicity studies by generation of pharmacokinetic data on the rate, extent, and duration of exposure. Toxicokinetics are normally integrated within the toxicity studies (concomitant); however, there are a number of circumstances when prospective, retrospective, or other ancillary types of toxicokinetic studies are performed in support of toxicity studies. The need for retrospective toxicokinetic studies arises when the original toxicity study was conducted with insufficient plasma concentration determinations, especially when pilot toxicity studies show lack of toxicity or unusual organ toxicities. Examples of ancillary toxicokinetic studies from the Drug Metabolism and Drug Safety departments at The R. W. Johnson Pharmaceutical Research Institute and from the scientific literature are provided that highlight the challenges associated with these alternate approaches. Each example includes a discussion of the rationale for the supportive toxicokinetic study, the specific experimental designs, the data interpretation, and the usefulness of the toxicokinetic data in decision-making. The ancillary toxicokinetic studies cited provided important information on establishing systemic exposure during long-term toxicity studies, allowing comparisons to human exposures, elucidating compound-related toxicities, and explaining lack of toxicity due to autoinduction and resulting low levels of parent compound.

[A comparative study of the antiarrhythmic action of bonnecor and the mesidide derivatives of alpha-azacycloalkane carboxylic acids]. / Sravnitel'noe izuchenie antiaritmicheskogo deistviia bonnekora i nekotorykh proizvodnykh mezididov al'fa-azatsikloalkankarbonovyykh kislot.

The antiarrhythmic properties of the dibenzazepine derivative bonnecor and derivatives of mesidides of alpha-azacycloalkanocarboxylic acids were studied in various experimental arrhythmia models. The comparative study revealed different antiarrhythmic effects in different arrhythmia models. Bonnecor was found to have a higher antiarrhythmic activity in most arrhythmic models. Tertiary salts were demonstrated to be more potent than quaternary ones.

[Possibilities for increasing the elimination rate of Bonnecor]. / Möglichkeiten zur Beschleunigung der Elimination von Bonnecor.

Bonnecor is excreted in rats both via urine (3/4) and bile (1/4). It was the aim of this study to find out suitable methods for detoxication of a poisoning with this antiarrhytmic drug. In vivo methods intended to enhance the renal excretion of Bonnecor (forced diuresis, changes in urinary pH-values, peritoneal dialysis) are not qualified for therapeutically relevant increase of Bonnecor elimination. Relating to this Bonnecor is quite comparable with other antiarrhythmic drugs or dibenzazepine derivatives. The hemoperfusion can be recommended for the therapy of a Bonnecor overdosage as a propping up of symptomatic methods of intensive care, which are precendentally indicated. Therefore the therapy of a Bonnecor poisoning seems to be more promising compared to intoxications with other antiarrhythmics. Among the adsorbents tested, the resin Wofatit UH91 is most suitable to remove Bonnecor from the organism. If hemoperfusion equipments are not available, hemodialysis can also be used for acceleration of Bonnecor elimination, although its effectivity is only one third of that of hemoperfusion.

[The relationship between the chemical structure and anti-arrhythmia action of a number of omega-aminoacyl-3-carbalcoxyaminodibenzazepines]. / Izuchenie zavisimosti mezhdu khimicheskim stroeniem i antiaritmicheskim deistviem v riadu omega-aminoatsil-3-karbalkoksiaminodibenzazepinov.

The antiarrhythmic activity of 20 derivatives of dibenzazepine (the effects on the maximal effective rabbit heart auricle contraction rate, aconitine-induced arrhythmia in rats under or without anesthesia) was studied. It was shown that the most active compounds are those with carbethoxyamine group in position 3 in combination with dimethylamino- or diethylamino-acetyl groups in position 5 of dibenzazepine ring. 5-dimethyl-aminoacetyl-10,11-dihydro-5H-dibenz b, f azepine (GS-015, bonnecor) was selected for the further detailed investigation.

[Pharmacological research on bonnecor and its metabolites]. / Farmakologicheskoe issledovanie bonnekora i ego metabolitov.

The antiarrhythmic and local anesthetic effects of 4 metabolites (G 491, ABD 19-200, ABD 19-199, ABD 19-205) of a new antiarrhythmic drug bonnecor (GS-015) were studied on the models of arrhythmias induced by aconitine (rats), barium chloride (rabbits), electrical fibrillation (cats), ouabain (dogs) as well as surface anesthesia (rabbit cornea). The side effects on the cardiovascular system were investigated on anesthetized cats. As compared with the original compound (bonnecor) metabolites G 491 and ABD 19-200 on different test models exhibited the action which on the antiarrhythmic terms was 2-14 times less weak than that of bonnecor but the metabolites were less toxic. Metabolites ABD 19-199 and ABD 19-205 reach the degree of effectiveness of bonnecor but their toxicity is higher. It follows from the above that the beneficial effect of bonnecor is not achieved by its metabolites.

[The relationship between the physicochemical and pharmacokinetic parameters and the anti-arrhythmia activity of bonnecor and its metabolites]. / Vzaimosviaz' mezhdu nekotorymi fiziko-khimicheskimi, farmakokineticheskimi parametrami i antiaritmicheskoi aktivnost'iu bonnekora i ego metabolitov.

The antioxidant properties of a new antiarrhythmic drug bonnecor and its main metabolites were determined by using chemoluminescence. A significant correlation was revealed between the physicochemical properties, antiarrhythmic activity, pharmacokinetic parameters of bonnecor and its metabolites.

[An experimental study of the safety of the preparation bonnecor in trials on dogs]. / Eksperimental'noe izuchenie bezopasnosti preparata bonnekora v oytakh na sobakakh.

The preclinical study of safety of an antiarrhythmic drug bonnecor (GS-015) was carried out in the experiments on dogs. Administration of the drug in a dose of 5 mg/kg was found to exert no significant effect on functions of the vital organs. The dosage of 15 mg/kg can produce in dogs changes of the hematological and biochemical parameters and cause functional disorders of the cardiac muscle and death of the animals. The data obtained indicate that in dogs the drug possesses a little therapeutic range.

Pharmacological profile of the new anticonvulsant etazepine.

The pharmacological profile of the new anticonvulsant etazepine (5,6-dihydro-5-methyl-11H-11-ethoxy-dibenzo[b,e]azepin-6-one) was investigated. It protected mice and rats from a wide variety of convulsant agents (maximal electroshock, pentetrazol (metrazole), bicuculline, strychnine, 3-mercaptopropionic acid, nicotine, cefazoline and kainic acid) at doses about 16-45 times lower than those exerting neurotoxic effects (depending on the test used). The anticonvulsant effect of etazepine was long-acting (more than 24 h) and did not seem to develop tolerance. Moreover, etazepine did not prolong thiopental-induced sleeping time. Based on pharmacological studies etazepine seems to exert its anticonvulsant effects by activating the GABAergic system.

The hypolipidemic activity of N(4-methyl-phenyl)diphenimide in rodents.

N(4-Methyl-phenyl)diphenimide afforded potent hypolipidemic activity in rodents. Serum cholesterol levels were reduced 67% and serum triglyceride were lowered 66% in rats by the drug after two weeks administration orally at 20 mg/kg/day. Rate limiting enzymes in the de novo synthesis of lipids in the liver were suppressed by the drug. Cholesterol was also removed from the body due to the drug accelerating bile excretion. Lipids removed from the blood compartment were not deposited in the organs of the body. VLDL and LDL cholesterol content was significantly reduced in rats treated with the drug with marked increase in HDL cholesterol after two weeks of administration. These data suggest that the drug may be useful in hyperlipidemic states and atherosclerosis in man, thus, further investigation of this class of chemicals is warranted.

[Summarized presentation of studies on the toxicology of 3-carbethoxyamino-5-dimethylamino-acetyl-10,11- dihydrobenz[b,f]azepine hydrochloride (Bonnecor, GS 015, AWD 19-166)]. / Zusammenfassende Darstellung der Untersuchungen zur Toxikologie von 3-Carbethoxyamino-5-dimethylamino-acetyl-10,11-dihydrodibenz- [b,f]azepin-hydrochlorid (Bonnecor, GS 015, AWD 19-166).

To ensure toxicologically the potential antiarrhythmic agent 3-carbethoxyamino-5-dimethylamino-acetyl-10,11-dihydro-dibenz[b,f] azepine hydrochloride (Bonnecor, GS 015, AWD 19-166), the following preclinical studies have been made up to the present: Determination of the acute toxicity on mice and rats, toxicity test on the rat by repeated applications, study as to the action of GS 015 on the prenatal development of the rat, diverse toxicologic studies on reproduction, mutagenity tests by using the DNA repair test and the Ames test. The results of these studies are represented in a summarized form. A good tolerance of GS 015 can be derived from the results of the preclinical studies gained up to now.

[Antiarrhythmic effectiveness of 3-carbalkoxyamino-5-(omega-aminoacyl)-10,11-dihydro-5H-dibenz-[b,f]- azepines]. / Antiarrhythmische Wirksamkeit von 3-Carbalkoxyamino-5-(omega-aminoacyl)-10,11-dihydro-5H-dibenz-[b,f]- azepinen.

The derivatives of a novel structure series of dibenzazepines dispose of intense antiarrhythmic properties. The relations between structure and effect in comparison with the antiarrhythmically active derivatives of phenothiazine (Ethmozine) are discussed. When substituting the beta-aminopropionyl chain with cyclic residue by means of a dimethylaminoacyl chain there appears a marked antifibrillatory action besides of the intense antiarrhythmic one. The compound 17, the 3-carbethoxyamino-5-dimethylaminoacetyl-dibenzazepine, proved to be the most efficacious compound in the course of the basic screening on two models: action on the effective refractory period in the rabbit's atrium and aconitin-induced arrhythmia in the conscious rat. In comparison with Ethmozin, an antiarrhythmic agent of the phenothiazine type, 17 shows a somewhat lower efficacy in case of i.v. application, but a distinctly intenser one was stated after oral administration. A profound test on the models: two-step coronary ligature in the dog according to Harris and electrofibrillation in the cat's heart, revealed an equally intense antiarrhythmic action but a considerably intenser antifibrillatory one. Therefore the compound 17 (abbreviated designation in the USSR: GS 015 or in the GDR: AWD 19-166) was provided for a thorough pharmacological and toxcological study.

[Cardiac disorders induced by mianserin in guinea pigs. Comparison with imipramine]. / Troubles cardiaques engendrés par la miansérine chez le cobaye. Comparaison avec l'imipramine.

Infusion of mianserin to anesthetized guinea-pigs induced electrocardiographic changes (auriculo-ventricular and intraventricular conduction lenghthening, bradycardia, QRS axis and T axis rotations) quite identical to those induced by imipramine. However they appeared later and mianserin produced cardiac arrest at higher dose (133 mg/kg) than did imipramine (73 mg/kg). In vitro, increasing concentrations of mianserin suppressed the electrical response of stimulated, isolated ventricular heart strips, but this suppression was obtained by a higher concentration (172 micrograms/ml) than with imipramine (80 micrograms/ml). Transmembrane potentials were not affected by a 5 or 10 micrograms/ml mianserin or a 5 micrograms/ml imipramine perfusion. With 20 micrograms/ml mianserin or 10 micrograms/ml imipramine, only a reduced duration of the action potential was obtained. With 50 micrograms/ml mianserin or 20 micrograms/ml imipramine, the resting potential was reduced. However, with imipramine only it was preceded by a decrease in the maximal velocity of depolarisation. These results show that mianserin induces transmembrane permeability changes which appear to differ from and to be less marked than those induced by imipramine. Molar sodium bicarbonate reversed in vivo and in vitro the electrophysiologic changes elicited either by mianserin or by imipramine, but with mianserin the transient improvement was followed by an aggravation of the cardiac troubles.

Relative acute cardiovascular toxicity induced by maprotiline, mianserin and nomifensine in conscious rabbits.

The relative acute cardiovascular toxicity among three novel antidepressants: maprotiline, mianserin and nomifensine, has been assessed in conscious rabbits ip injected at 50 mg/kg, throughout a 150 min observation period. No death was observed in mianserin rabbits (n = 6), but 3 in the maprotiline rabbits (n = 8) and 1 death in the nomifensine group (n = 8), within the 2 hours. Cardiac output and renal blood flow were determined by the radioactive Sephadex microspheres method. Cardiac output values were significantly lowered (-29%) at 120 min only in mianserin rabbits, whereas renal blood flow values were reduced by 46.8% (mianserin, 35.8% (maprotiline) and 28% (nomifensine) at 120 min. In mianserin and maprotiline rabbits left ventricular pressure and mean arterial pressure fell significantly, but remained unchanged in nomifensine group. ECG disturbances consisting of ventricular and supraventricular extrasystoles were seen in all the injected rabbits, but QRS widening and right bundle branch block were solely observed after maprotiline and mianserin. Nomifensine rabbits experienced severe seizures with hypocapnia and metabolic acidosis. The drug myocardial/plasma ratio ranged between 59.3 (maprotiline) 13.25 (mianserin) and 0.92 (nomifensine). A rise in plasma catecholamines (epinephrine) was documented after mianserin but not after nomifensin and maprotiline. Nomifensine exhibited much lesser cardiotoxicity than mianserin and maprotiline at this dose (50 mg/kg), but induced more convulsions.