Synthesis and biological activity of pyrimido[2,1-b][1,3]thiazine, [1,3]thiazino[3,2-a]purine and [1,2,3]triazolo[4,5-d][1,3]thiazino[3,2-a]pyrimidine derivatives and thiazole analogues.

Some series of thiazolo[3,2-a]pyrimidine, pyrimido[2,1-b] [1,3]thiazine, thiazolo[3,2-a]purine, [1,3]thiazino[3,2-a]purine, thiazolo[3,2-a][1,2,3]triazolo[4,5-d]pyrimidine and [1,2,3]triazolo[4,5-d][1,3]thiazino[3,2-a]pyrimidine derivatives, variously functionalized, were prepared. The compounds were tested for antimicrobial and antimycotic activity on a number of strains, namely: E. coli, Proteus vulgaris, P. mirabilis, Pseudomonas aeruginosa, Salmonella sp., Staphylococcus aureus, S. faecalis, Bacillus subtilis, Sarcina lutea, Candida albicans, C. tropicalis, Aspergillus sp., and for antiviral activity on Herpes simplex virus Type 1, Vesicular stomatitis virus and Coxsackievirus B5. The compounds proved to be devoid of activity against viruses and gram-negative bacteria, while some of them exhibited modest activity against gram-positive bacterial strains.     

Synthesis and pharmacological evaluation of CNS activities of [1,2,3]triazolo[4,5-b][1,5]-, imidazolo[4,5-b][1,5]-, and pyrido[2,3-b][1,5]benzodiazepines. 10-Piperazinyl-4H-1,2,3-triazolo[4,5-b][1,5]benzodiazepines with neuroleptic activity

The synthesis of [1,2,3]triazolo[4,5-b][1,5]-, imidazolo[4,5-b][1,5]-, and pyrido[2,3-b][1,5]benzodiazepines is described. The antidopaminergic and anticholinergic activities of the compounds have been examined by the respective in vitro [3H]spiperone and [3H]QNB receptor binding assay. The neuroleptic potential has been further evaluated in terms of their ability to produce hypothermia and catalepsy in mice and a conditioned avoidance response in rats. Only compounds from the triazolobenzodiazepine series show antipsychotic potential. The lack of activity in the imidazolo- and pyridobenzodiazepine series indicates that the basicity of the heteroarene moiety may be determinant for activity.     

Synthesis and biological activity of new heterocyclic structures: [1,3]thiazino[2,3-i]purine, thiazolo[3,2-c] [1,2,3]triazolo[4,5-e]pyrimidine and [1,2,3]triazolo [4', 5': 4,5] pyrimido[6,1-b][1,3]thiazine.

Some derivatives of thiazolo[3,2-c]pyrimidine, pyrimido[6,1-b][1,3]thiazine, thiazolo[2,3-i]purine, [1,3]thiazino[2,3-i]purine, thiazolo[3,2-c][1,2,3]triazolo[4,5-e]pyrimidine and [1,2,3]triazolo[4',5':4,5]pyrimido[6,1-b][1,3]thiazine were prepared. The compounds were tested for antimicrobial and antimycotic activity on a number of strains, namely, Escherichia coli, Proteus vulgaris, P. mirabilis, Pseudomonas aeruginosa, Salmonella sp., Staphylococcus aureus, Streptococcus faecalis, Bacillus subtilis, Sarcina lutea, Candida albicans, Aspergillus sp., and for antiviral activity on Herpes simplex virus, Type 1 (HSV-1), Vesicular stomatitis virus (VSV) and Coxsackievirus B5 (CoxB5). The compounds proved to be devoid of activity against viruses, mycetes and gram-negative bacteria, while some of them exhibited a modest activity against gram-positive bacterial strains.     

5-amino-2-phenyl[1,2,3]triazolo[1,2-a][1,2,4]benzotriazin-1-one: a versatile scaffold to obtain potent and selective A3 adenosine receptor antagonists

Binding assays on human A1, A2A, and A3 adenosine receptors (ARs) and functional studies on A2B ARs revealed that various 2-phenyl[1,2,3]triazolo[1,2-a][1,2,4]benzotriazin-1,5(6H)-diones VIII, previously reported as ligands at the central benzodiazepine receptor (BzR), possess nanomolar affinity at the A3 AR. Replacement of the amide of VIII with an amidine moiety gave the 5-amino-2-phenyl[1,2,3]triazolo[1,2-a][1,2,4]benzotriazin-1-ones IX, which maintain a nanomolar potency at the A3 AR with selectivity over the BzR. Insertion of a p-methoxybenzoyl at the 5-amino moiety enhanced A3 AR affinity and selectivity over the A1, A2A, and A2B ARs. The best result of our lead optimization efforts is 9-chloro-5-(4-methoxybenzoyl)amino-2-phenyl[1,2,3]triazolo[1,2-a][1,2,4]benzotriazin-1-one (23), which displayed a Ki of 1.6 nM at the A3 AR and no significant affinity at the other ARs or the BzR. Docking simulations on selected ligands into a model of the A3 AR allowed us to rationalize the structure-activity relationships of phenyltriazolobenzotriazindiones VIII and aminophenyltriazolobenzotriazinones IX at the molecular level.     

Design and synthesis of 4-substituted indolo[3,2-e][1,2,3]triazolo[1,5-a]pyrimidine derivatives with antitumor activity

New derivatives of the indolo[3,2- e][1,2,3]triazolo[1,5- a]pyrimidine system, substituted in the 4 position, were designed as novel antitumor agents because of their theoretical capability to form stable complexes with DNA fragments. The calculated free energies of binding were found in the range -12.76 --> -39.68 Kcal/mol. The docking studies revealed a common binding mode with the chromophore intercalated between GC base pairs, whereas the side chain lies along the minor groove. Compounds, selected on the basis of the docking studies and suitably synthesized, showed antiproliferative activity against each type of tumor cell line investigated, generally in the low micromolar range. The more active derivatives were shown to be 1eJ and 1eL, endowed with significant antiproliferative activity against the renal and CNS subpanels, respectively. A mechanism of action closely related to the DNA-interacting drugs can be supposed, although, alternative mechanisms, similar to those of the anthracyclines, can also operate.     

Studies on the synthesis of condensed pyridazine derivatives. III. Synthesis and benzodiazepine receptor binding studies of condensed triazolopyridazine derivatives

A series of 6H-(1)benzothiopyrano[3,4-e][1,2,4]triazolo[4,3- b]pyridazines and 6,7-dihydro-(1)benzothiepino[4,5- e][1,2,4]triazolo [4,3-b]pyridazines were prepared and tested for their ability to displace [3H] diazepam from rat brain membranes. An approximately planar shape of these molecules was essential for high affinity to the benzodiazepine receptor. Among them, 11-aryl compounds in the latter series were found to have high affinity to the benzodiazepine receptor. 11-Phenyl- and 11-thienyl- 6,7-dihydro-(1)benzothiepino[4,5-e][1,2,4]triazolo[4,3- b]pyridazine (3b-5 and 3b-11 respectively) showed the potent affinity comparable to that of diazepam. The structure-activity relationships are also discussed.     

Synthesis and evaluation of pharmacological and pharmacokinetic properties of 11H-[1,2,4]triazolo[4,5-c][2,3]benzodiazepin-3(2H)-ones

A series of 2,3-benzodiazepine derivatives has been previously described as noncompetitive AMPA-type glutamate receptor antagonists potentially useful for treatment of epilepsy. To further explore the structure-activity relationships of AMPA antagonists, a series of 11H-[1,2,4]triazolo[4,5-c][2,3]benzodiazepin-3(2H)-ones (6) was synthesized starting from the corresponding bicyclic 1-aryl-3, 5-dihydro-7,8-dimethoxy-4H-2,3-benzodiazepin-4-ones (2, CFM). The new compounds were found to possess anticonvulsant effects against seizures induced both by means of auditory stimulation in DBA/2 mice and by pentylenetetrazole or maximal electroshock in Swiss mice. In addition, they antagonize the AMPA-induced seizures, and their anticonvulsant activity is reversed by pretreatment with aniracetam, thus suggesting the involvement of AMPA receptors. The pharmacological studies revealed that the 11H-[1,2,4]triazolo[4, 5-c][2,3]benzodiazepin-3(2H)-ones (6) herein reported show anticonvulsant activity comparable to that of their bicyclic precursors. Furthermore, an HPLC study put in evidence that these tricyclic derivatives 6 were converted in vivo into the corresponding 2, the agents likely to be mainly responsible for the anticonvulsant properties observed.     

Antibacterial, antifungal and anticonvulsant evaluation of novel newly synthesized 1-[2-(1H-tetrazol-5-yl)ethyl]-1H-benzo[d][1,2,3]triazoles

Several novel 1-[2-(1H-tetrazol-5-yl) ethyl]-1H-benzo[d][1,2,3]triazoles (3a-h) have been synthesized by the condensation of 1-[2-(1H-tetrazol-5-yl)-ethyl]-1H-benzotriazole (2) and appropriate acid chlorides. 1-[2-(1H-tetrazol-5-yl)-ethyl]-1H-benzotriazole (2) was synthesized by reacting 3-(1H-benzo[d][1,2,3]triazol-1-yl)propanenitrile with sodium azide and ammonium chloride in the presence of dimethylformamide. The synthesized compounds were characterized by IR and PMR analysis. The titled compounds were evaluated for their in-vitro antibacterial and antifungal activity by the cup plate method and anticonvulsant activity evaluated by the maximal electroshock induced convulsion method in mice. All synthesized compounds exhibited moderate antibacterial activity against Bacillus subtilis and moderate antifungal activity against Candida albicans. Compounds 5-(2-(1H-benzo[d][1,2,3]triazo-1-yl)ethyl)-1H-tetrazol-1-yl)(4-aminophenyl)methanone 3d and 5-(2-(1 H-benzo[d][1,2,3]triazo-1-yl)ethyl)-1H-tetrazol-1-yl)(2-aminophenyl)methanone 3e elicited excellent anticonvulsant activity.     

2-benzazepines. 5. Synthesis of pyrimido[5,4-d][2]benzazepines and their evaluation as anxiolytic agents

A series of 5H-pyrimido[5,4-d][2]benzazepines has been synthesized, starting from the corresponding 2-benzazepin-5-ones, and evaluated as potential anxiolytic agents. Selected compounds from this series show a pharmacological profile of action different than that of diazepam. They are more potent than diazepam in the anti-pentylenetetrazole test and in the [3H]diazepam binding assay, yet show less activity in the inclined screen test. A pharmacological data profile is given for 9-chloro-7-(2-chlorophenyl)-5H-pyrimido[5,4-d] [2]benzazepine (7c). The structure-activity relationships of these potential anxiolytic agents are discussed.     

Anxiolytic properties of certain annelated [1,2,4]triazolo[1,5-c]pyrimidin-5(6H)-ones.

Modification of the benzodiazepine (BZ) receptor binding template 2-aryl[1,2,4]triazolo[1,5-c]quinazolin-5(6H)-one by replacement of the annelated benzene ring with various alicyclic and heterocyclic moieties led to novel structures with potent BZ receptor binding affinity. High affinity was found in some cycloalkyl-annelated [1,2,4]triazolo[1,5-c]pyrimidin-5(6H)-ones and in some 7,8,9,10-tetrahydropyrido[3,4-e][1,2,4]triazolo[1,5-c]pyrimidin- 5(6H)-ones, in which the degree of activity was strongly dependent on the N-substituent in the 9-position. Nine compounds with BZ receptor IC50 binding affinity values equal or superior to diazepam were evaluated in secondary screening. One of these, 9-benzyl-2-phenyl-7,8,9,10-tetrahydropyrido[3,4-e] [1,2,4]triazolo[1,5-c]pyrimidin-5(6H)-one, showed good activity in rats as a potential anxiolytic agent without sedative liability. However, it increased the rotorod deficit produced by ethanol at anxiolytic doses, an indication of alcohol interaction. Thus, none of the compounds showed an advantage over CGS 9896 (Yokoyama et al. J. Med. Chem. 1982, 25, 337-339), which is free of sedative and alcohol interaction potential as measured by the test procedures described.     

Synthesis and antimicrobial evaluation of naphtho[2,1-b]pyrano[2,3-d]pyrimidine and pyrano[3,2-e][1,2,4]triazolo[1,5-c]pyrimidine derivatives

Several novel naphtho[2,1-b]pyrano[2,3-d]pyrimidines, pyrano[3,2-e][1,2,4]triazolo[1,5-c]pyrimidines and their coumarin-3-yl derivatives were synthesized. Some of these derivatives exhibited pronounced antimicrobial activities.     

Synthesis and benzodiazepine receptor binding of 1H-pyrrolo[2,1-C][1,4]benzothiazines

The pyrrolo[2,1-c][1,4]benzothiazines 2a-n and the pyrrolo[2,1-c][1,4]thiazine 13 were prepared and tested for their ability to displace specific [3H]diazepam binding from rat brain membranes. Such compounds were found essentially devoid of binding affinity for the benzodiazepine receptor.     

Novel diamino derivatives of [1,2,4]triazolo[1,5-a][1,3,5]triazine as potent and selective adenosine A2a receptor antagonists

Piperazine derivatives of 2-furanyl[1,2,4]triazolo[1,5-a][1,3,5]triazine have recently been demonstrated to be potent and selective adenosine A(2a) receptor antagonists with oral activity in rodent models of Parkinson's disease. We have replaced the piperazinyl group with a variety of linear, monocyclic, and bicyclic diamines. Of these diamines, (R)-2-(aminomethyl)pyrrolidine is a particularly potent and selective replacement for the piperazinyl group. With this diamine component, we have been able to prepare numerous analogues with low nanomolar affinity toward the A(2a) receptor and good selectivity with respect to the A(1) receptor (>200-fold in some cases). Selected analogues from this series of [1,2,4]triazolo[1,5-a][1,3,5]triazine have now been shown to be orally active in the mouse catalepsy model.     

Synthesis, structural characterization and biological evaluation of novel [1,2,4]triazolo [1,5-b][1,2,4]benzothiadiazine-benzothiazole conjugates as potential anticancer agents

Two series of 10-substituted 5,5-dioxo-5,10-dihydro[1,2,4]triazolo[1,5-b][1,2,4]benzothiadiazine 2-methyl/ethyl sulfanyl benzothiazole derivatives (5a-d) and 10-substituted 5,5-dioxo-5,10-dihydro[1,2,4]triazolo[1,5-b][1,2,4] benzothiadiazine 2-phenoxy benzothiazole derivatives (16a-c) were synthesized and their structures confirmed by NMR, MS, IR and X-ray crystallography. These compounds were evaluated for their cytotoxicity against 60 human tumour cell lines. One of the synthesized compounds (5b) exhibited significant inhibitory activity against most of the cell lines and has been further evaluated for the five-dose screening.     

Pyrazolo[3,4-d][1,2,3]triazole-1-carboxamides and 5-alkylaminopyrazolo[3,4-d]oxazoles: synthesis and evaluation of the in vitro antifungal activity.

A series of N-alkyl-N'-(4-diazo-5-pyrazolyl)-ureas (4) was thermally and photochemically converted into pyrazolo [3,4-d][1,2,3]triazole derivatives (5,6) and 5-alkylaminopyrazolo[3,4-d]oxazoles (7) respectively. The products were tested for in vitro antifungal activity against Fusarium culmorum, Botrytis cinerea, Phoma betae, Pythium ultimum, Sclerotinia minor and Rhizoctonia solani. The MIC and ED50 values of compound (6) against some of the test fungi were comparable to those of the reference fungicides iprodione and mancozeb.     

Thiophene systems. 5. Thieno[3,4-b][1,5]benzoxazepines, thieno[3,4-b][1,5]benzothiazepines, and thieno[3,4-b][1,4]benzodiazepines as potential central nervous system agents

10-(Alkylamino)thieno[3,4-b][1,5]benzoxazepines (3) and 10-(alkylamino)thieno[3,4-b][1,5]benzothiazepines (4) were prepared by derivatization of the respective lactams (7 and 8) via phosphorus pentachloride and subsequent condensation with the appropriate alkylamines. 9-(Alkylamino)-4H-thieno[3,4-b][1,4]benzodiazepines (5) were prepared by titanium tetrachloride catalyzed condensation of the lactam 11 with alkylamines. 9-(Alkylamino)-4-methylthieno[3,4-b][1,4]benzodiazepines (6) were prepared by reductive alkylation of 5. The compounds were tested for potential neuroleptic activity by means of the blockade of d-amphetamine lethality in aggregated mice and/or effects on locomotor activity in rats. Antidepressant activity was examined using inhibition of tetrabenazine-induced depression in mice. Most of the title compounds 3-6 were found to have neuroleptic activity. In addition, introduction of a 3-chloro substituent in the oxygen and sulfur systems (3p and 4c), as well as introduction of an N-alkyl in the dinitrogen system (6), was found to produce antidepressant effects. Structure-activity relationships are discussed.     

Synthesis and in vitro antifungal and cytotoxicity evaluation of substituted 4,5-dihydronaphtho[1,2-d][1,2,3]thia(or selena)diazoles

Unsubstituted 4,5-dihydronaphtho[1,2-d][1,2,3]thia (or selena)diazoles (2a, 2b), prepared from the semicarbazone (1a), were nitrated using fuming nitric acid at 0 degrees C to yield various mono-nitrated dihydronaphthalenes (3a-3e). Related sulfamoyl derivatives (4a, 4b) were prepared using chlorosulfonic acid, followed by the addition of ammonia solution. Synthesis of 6,9-dimethoxy-4,5-dihydronaphtho[1,2-d][1,2,3]thiadiazole derivative (2c) was performed using 5,8-dimethoxy-alpha-tetralone semicarbazone (1b) and thionylchloride at low temperature. At 10 ppm concentration, all compounds showed low toxicity (higher than 80% survival) on brine shrimps, while at 100 ppm concentration compounds 2d, 3d, and 4b exhibited toxicity (less than 60% survival). Compounds 3a, 3e, and especially 4a showed significant antifungal activity against Cryptococcus neoformans. Compound 4a, while being the most active antifungal agent in this series, possessed low toxicity.     

Cholecystokinin antagonists. Synthesis and biological evaluation of 4-substituted 4H-[1,2,4]triazolo[4,3-a][1,4]benzodiazepines

A series of 4-substituted 4H-[1,2,4]triazolo[4,3-a][1,4]benzodiazepines was prepared by standard methodology. These compounds were tested in vitro as antagonists of the binding of [125I]cholecystokinin (CCK) to rat pancreas and guinea pig brain receptors and of the binding of [125I]gastrin to guinea pig gastric glands. All compounds proved to have greater affinity for the peripheral CCK receptor with some analogues having IC50's in the subnanomolar range. In vivo activity of selected compounds in mice is presented and the structure/activity profile of this class of benzodiazepines as CCK antagonists is discussed.     

Quinazolines and 1,4-benzodiazepines. 81. s-Triazolo[4,3-a][1,4]benzodiazepines by oxidative cyclization of hydrazones

s-Triazolo[4,3-a][1,4]benzodiazepines bearing various substituents in the 1 position were prepared by oxidative cyclization of the appropriate aldehyde hydrazones of 2-hydrazinobenzodiazepines. Diethyl azodicarboxylate and activated manganese dioxide were used as oxidizing agents. The new triazolo compounds were active in the CNS tests but none of them reached the potency of the known triazolobenzodiazepines.     

Synthesis and benzodiazepine receptor binding of 5H-pyrido[2,1-C][1,4]benzothiazines

The pyrido[2,1-c][1,4]benzothiazines 1a-t and the pyrido[2,1-c][1,4]thiazines 7a,b were prepared and tested for their ability to displace specific [3H]diazepam binding from rat brain membranes. Some of the examined compounds of type 1 and 7b showed moderate binding affinity for the benzodiazepine receptor.