Synthesis and in-vitro inotropic evaluation of 2-(4-substitutedbenzyl-1,4-diazepan-1-yl)-N-(4,5-dihydro-1-phenyl-[1,2,4]triazolo[4,3-a]quinolin-7-yl)acetamides

We describe the synthesis and positive inotropic evaluation of a series of 2-(4-substitutedbenzyl-1,4-diazepan-1-yl)-N-(4,5-dihydro-1-phenyl-[1,2,4]triazolo[4,3-a]quinolin-7-yl)acetamides by measuring left atrial stroke volume in preparations of isolated rabbit-heart. Several compounds were developed from, and showed favorable activities compared with the standard drug milrinone. Compound 5o was the most potent with an increased stroke volume of 9.17?±?0.14% (milrinone 2.47?±?0.08%) at 3?×?10?? M in our in-vitro study. The chronotropic effects of those compounds having inotropic effects were also evaluated.     

Synthesis and Positive Inotropic Evaluation of (E)‐2‐(4‐Cinnamylpiperazin‐1‐yl)‐N‐(1‐substituted‐4,5‐dihydro‐[1,2,4]triazolo[4,3‐a]quinolin‐7‐yl)acetamides

A series of (E)‐2‐(4‐cinnamylpiperazin‐1‐yl)‐N‐(1‐substituted‐4,5‐dihydro‐[1,2,4]triazolo[4,3‐a]quinolin‐7‐yl)acetamides were synthesized and evaluated for their positive inotropic activity by measuring the left atrium stroke volume on isolated rabbit heart preparations. This class of compounds presented favorable in vitro activity compared with the standard drug, milrinone, among which N‐(1‐(3‐chlorophenyl)‐4,5‐dihydro‐[1,2,4]triazolo[4,3‐a]quinolin‐7‐yl)‐2‐(4‐cinnamylpiperazin‐1‐yl)acetamide 5e was found to be the most potent with 16.58 ± 0.11% increased stroke volume (milrinone: 2.46 ± 0.07%) at a concentration of 3 × 10^?5 M. The chronotropic effects of the compounds having inotropic effects were also evaluated.     

Synthesis and anti-inflammatory activity evaluation of novel 7-alkoxy-1-amino-4,5-dihydro[1,2,4]triazole[4,3-a]quinolines

In this study, a novel series of 7-alkoxy-1-amino-4,5-dihydro[1,2,4]triazole[4,3-a]quinolines were synthesized by using 6-hydroxy-3,4-dihydro-2(1H)-quinolone as the starting material. These compounds were evaluated for anti-inflammatory activity through monitoring their ability to inhibit xylene-induced ear edema in mice. Some of the tested compounds exhibited significant activity, and the compounds 5f (7-(benzyloxy)-4,5-dihydro[1,2,4]triazolo[4,3-a]quinolin-1-amine) and 5i (7-(p-chlorobenzyloxy)-4,5-dihydro[1,2,4]triazolo[4,3-a]quinolin-1-amine) showed the highest anti-inflammatory activity (52% and 58% inhibition, respectively, at 2 h pre-administration) which were comparable to or even slightly more potent than the reference drug ibuprofen (55%). Furthermore, the structure-activity relationship of these 1,2,4-triazole quinolines was demonstrated.     

Synthesis and Positive Inotropic Evaluation of 2‐(4‐(4‐Substituted benzyloxy)‐3‐methoxybenzyl)‐1,4‐diazepan‐1‐yl)‐N‐(4,5‐dihydro‐1‐methyl[1,2,4]triazolo[4,3‐a]quinolin‐7‐yl)‐acetamides

In an attempt to search for more potent positive inotropic agents, a series of 2‐(4‐(4‐substituted benzyloxy)‐3‐methoxybenzyl)‐1,4‐diazepan‐1‐yl)‐N‐(4,5‐dihydro‐1‐methyl[1,2,4]triazolo[4,3‐a]quinolin‐7‐yl)acetamides was synthesized and their positive inotropic activities were evaluated by measuring left atrium stroke volume on isolated rabbit‐heart preparations. Several compounds showed favorable activity compared with the standard drug Milrinone among which 2‐(4‐(4‐(2‐chlorobenzyloxy)‐3‐methoxybenzyl)‐1,4‐diazepan‐1‐yl)‐N‐(4,5‐dihydro‐1‐methyl‐[1,2,4]triazolo[4,3‐a]quinolin‐7‐yl)acetamide 6e was found to have the most desirable potency with the 6.79 ± 0.18% increased stroke volume (Milrinone: 1.67 ± 0.64%) at a concentration of 1×10^–5 M in our in‐vitro study. The chronotropic effects of those compounds having inotropic effects were also evaluated in this work.     

Synthesis and Biological Evaluation of [1,2,4]Triazolo[3,4‐a]phthalazine and Tetrazolo[5,1‐a]phthalazine Derivatives Bearing Substituted Benzylpiperazine Moieties as Positive Inotropic Agents

Two series of [1,2,4]triazolo[3,4‐a]phthalazine and tetrazolo[5,1‐a]phthalazine derivatives bearing substituted benzylpiperazine moieties have been synthesized and evaluated for their positive inotropic activity by measuring left atrium stroke volume on isolated rabbit heart preparations. The majority of the derivatives exhibited better in vitro activity than the existing drug, milrinone, and 6‐((4‐(4‐methoxyphenyl)piperazin‐1‐yl)methyl)tetrazolo[5,1‐a]phthalazine. 8 m in particular was identified as the most potent with an increased stroke volume of 12.02 ± 0.20% (milrinone: 2.46 ± 0.07%) at a concentration of 3 × 10^–5 m . The chronotropic effects of the compounds that exhibited good potency were also evaluated.     

Synthesis of 2-substituted-7-heptyloxy-4,5-dihydro-[1,2,4]-triazolo[4,3-a]quinolin-1(2H)-ones with anticonvulsant activity

A series of 2-substituted-7-heptyloxy-4,5-dihydro-[1,2,4]triazolo[4,3-a]quinolin-1(2H)-ones was synthesized. The anticonvulsant effect and neurotoxicity of the compounds were calculated with maximal electroshock (MES) test, subcutaneous pentylenetetrazole (sc-PTZ), and rotarod tests with intraperitoneally injected mice. Among the synthesized compounds, 2-propionyl-7-heptyloxy-4,5-dihydro-[1,2,4]triazolo[4,3-a]quinoline-1(2H)-one 4b was the most active one and also had the lowest toxicity. In the anti-MES potency test, it showed median effective dose (ED(50)) of 8.2 mg/kg, median toxicity dose (TD(50)) of 318.3 mg/kg, and the protective index (PI) of 39.0 which is much greater than the PI of the reference drugs phenytoin and carbamazepine.     

Synthesis and anticonvulsant activity of 1-substituted-7-benzyloxy-4,5-dihydro-[1,2,4]triazolo[4,3-a]quinoline

Starting from 6-hydroxy-3,4-dihydro-1H-quinoline-2-one, a series of 1-substituted-7-benzyloxy-4,5-dihydro-[1,2,4]triazolo[4,3-a]quinolines was synthesized and their structures were characterized using IR, 1H-NMR, MS, and elemental analysis techniques. Anticonvulsant activity was evaluated in the maximal electroshock (MES) test, subcutaneous pentylenetetrazol (scMet) test, and rotarod neurotoxicity test. The most active compound was 7-benzyloxy-4,5-dihydro-[1,2,4]triazolo[4,3-a]quinoline 4a. Its ED50 in the MES and scMet tests was 17.3 and 24 mg.kg-1, respectively. The safest compound was 4 g, 1-phenyl-7-benzyloxy-4,5-dihydro-[1,2,4]triazolo[4,3-a]quinoline, with TD50 and protective index (PI) (PI=TD50/ED50) values of greater than 300 mg.kg-1 and 13, respectively. The PI value of compound 4 g was better than that of most marketed drugs. Structure-activity relationships are also described in this paper.     

Synthesis and negative inotropic effects evaluation of 7-substituted-4,5-dihydro-[1,2,4]oxadiazolo[4,3-a]quinolin-1-ones

A series of 7-alkoxy-4,5-dihydro-[1,2,4]oxadiazolo[4,3-a]quinolin-1-ones was synthesized and their negative inotropic effects were evaluated by measuring the left atrium stroke volume in isolated rabbit heart preparations. All compounds moderated the cardiac workload by decreasing heart rate and contractility (inotropic effects). Among them, compound 6 was found to be best potent with a ?28.89 ± 1.91 % decrease in the stroke volume at a concentration of 3 × 10^?5 M in our in vitro study.     

Cardiotonic agents. 2. Synthesis and structure-activity relationships of 4,5-dihydro-6-[4-(1H-imidazol-1-yl)phenyl]-3(2H)-pyridazinones: a new class of positive inotropic agents

A series of 4,5-dihydro-6-[4-(1H-imidazol-1-yl)phenyl]-3(2H)-pyridazinones and related compounds were synthesized and evaluated for positive inotropic activity. Most members of this series produced dose-related increases in myocardial contractility that were associated with relatively minor increases in heart rate and decreases in systemic arterial blood pressure. Introduction of a methyl substituent at the 5-position of 1 (CI-914) produced the most potent compound in this series (11, CI-930). Compound 1 is more potent than amrinone whereas compound 11 is more potent than milrinone. The inotropic effects of 1 and 11 are not mediated via stimulation of beta-adrenergic receptors. Selective inhibition of cardiac phosphodiesterase fraction III represents the principal component of the positive inotropic action of 1 and 11.     

Synthesis and binding studies of 1-arylpyrazolo[4,5-c]- and 2-arylpyrazolo[4,3-c]quinolin-4-ones. I

The syntheses of some 2-aryl-3-methyl-4,5-dihydro-2H-pyrazolo [4,3-c] quinolin-4-ones and 1-aryl-3-methyl-4,5-dihydro-1H-pyrazolo-[4,5-c] quinolin-4-ones are reported. Some of the latter have shown a high activity in displacing specific [3H]-flunitrazepam binding from bovine brain membranes.     

Cardiotonic agents. 3. Synthesis and biological activity of novel 6-(substituted 1H-imidazol-4(5)-yl)-3(2H)-pyridazinones

Several 6-(substituted 1H-imidazol-4(5)-yl)-3(2H)-pyridazinones were synthesized and evaluated for positive inotropic activity. The 1H-imidazol-4-yl regioisomers 4,5-dihydro-6-(1-methyl-2-phenyl-1H-imidazol-4-yl)-3(2H)-pyridazinone (25a) and 6-(1-methyl-2-phenyl-1H-imidazol-4-yl)-3(2H)-pyridazinone (28a) were potent positive inotropic agents. By contrast, the corresponding 1H-imidazol-5-yl regioisomers 25b and 28b were only weak positive inotropic agents. Compounds 25a and 28a were also potent inhibitors of cardiac phosphodiesterase fraction III.     

Synthesis of 8-alkoxy-4,5-dihydro-[1,2,4]triazole[4,3-a]quinoline-1-ones and evaluation of their anticonvulsant properties

A series of 8-alkoxy-4,5-dihydro-[1,2,4]triazole[4,3-a]quinoline-1-one derivatives were synthesized using 7-hydroxy-3,4-dihydro-2(1H)-quinolone as the starting material. Their anticonvulsant activities were evaluated by the maximal electroshock test (MES) and the subcutaneous pentylenetetrazole test (sc-PTZ), and their neurotoxicities were measured by the rotarod neurotoxicity test (Tox). The tests demonstrated that 8-hexyloxy-4,5-dihydro-[1.2.4]triazole[4.3-a]quinoline-1-one (4e) and 8-heptyloxy-4,5-dihydro-[1,2,4] triazole[4,3-a]quinoline-1-one (4f) were the most potent anticonvulsants, with 4e having ED50 values of 17.17 mg/kg and 24.55 mg/kg and protective index (PI = TD50/ED50) values of 41.9 and 29.3 in the MES and sc-PTZ tests, respectively, and 4f having ED50 values of 19.7 mg/kg and 21.2 mg/kg and PI values of 36.5 and 33.9 in the MES and sc-PTZ tests, respectively. The PI values of 4e and 4f were many fold better than that of the marketed drugs phenytoin, carbamazepine, phenobarbital and valproate, which have PI values in the range of 1.6-8.1 in the MES test and < 0.22-5.2 in the sc-PTZ test. Structure-activity relationships were also discussed.     

Synthesis and pharmacological investigation of novel 1-substituted-4-(4-substituted phenyl)-4H-[1,2,4]triazolo[4,3-a]quinazolin-5-ones as a new class of H1-antihistamine agents

A series of novel 1-substituted-4-(4-substituted phenyl)-4H-[1,2,4]triazolo[4,3-a]quinazolin-5-ones was synthesized by the cyclization of 2-hydrazino-3-(4-substituted phenyl)-3H-quinazolin-4-one with various one-carbon donors. The starting material, 2-hydrazino-3-(4-substituted phenyl)-3H-quinazolin-4-one, was synthesized from 4-substituted aniline by a novel innovative route. When tested for in-vivo H1-antihistamine activity on conscious guinea-pigs, all the test compounds significantly protected the animals against histamine-induced bronchospasm. The compound 1-methyl-4-(4-chloro phenyl)-4H-[1,2,4]triazolo[4,3-a]quinazolin-5-one (VII) was more potent (72.71% protection), and 1-methyl-4-(4-methoxy phenyl)-4H-[1,2,4]triazolo[4,3-a]quinazolin-5-one (II) was equipotent (71% protection), when compared with the reference standard, chlorpheniramine maleate (71% protection). Compounds II and VII showed negligible sedation (5% and 8% respectively) when compared with chlorpheniramine maleate (25%). Compounds II and VII could serve as prototype molecules for further development as a new class of H1-antihistamines.     

4-Cyclohexyl-1-substituted-4H-[1,2,4]triazolo [4,3-a] quinazolin-5-ones: novel class of H1-antihistaminic agents

A series of novel 1-substituted-4-cyclohexyl-4H-[1,2,4]triazolo [4,3-a] quinazolin-5-ones were synthesized by the cyclization of 3-cyclohexyl-2-hydrazino-3H-quinazolin-4-one with various one carbon donors. When tested for their in vivo H1-antihistaminic activity on guinea-pigs, all the test compounds protected the animals from histamine induced bronchospasm significantly. The compound 4-cyclohexyl-1-methyl-4H-[1,2,4]triazolo[4,3-a] quinazolin-5-one (II) emerged as the most active compound of the series and it is more potent (72.96% protection) when compared to the reference standard chlorpheniramine maleate (71.00% protection). The compound II shows negligible sedation (9%) when compared to chlorpheniramine maleate (30%). Hence, it could serve as prototype molecule for further development as a new class of H1-antihistamines.     

Cardiotonic agents. 5. 1,2-Dihydro-5-[4-(1H-imidazol-1-yl)phenyl]-6-methyl-2-oxo-3- pyridinecarbonitriles and related compounds. Synthesis and inotropic activity

Several 1,2-dihydro-5-(substituted phenyl)-2(1H)-pyridinones were synthesized and evaluated for inotropic activity. 1,2-Dihydro-5-[4-(1H-imidazol-1-yl)phenyl]-6-methyl-2-oxo-3- pyridinecarbonitrile (5a) and the corresponding unsubstituted analogue 14a were the most potent positive inotropic agents in this series. Although the 4,6-dimethyl analogue 6a retained most of the activity of 5a, the 4-methyl analogue 8a was substantially less potent. The synthesis and structure-activity relationships are discussed.     

3,4-Dihydro-1H-1,4-oxazino[4,3-a]indoles as potential antidepressants.

A series of 3,4-dihydro-1H-1,4-oxazino[4,3-a]indoles bearing basic side chains has been synthesized by a novel chemical process. These compounds have been screened for potential antidepressant activity. One of these derivatives, 3,4-dihydro-1,10-dimethyl-1-(3-methylaminopropyl)-1H-1,4-oxazino[4,3-a]indole (AY-23,673), was particularly potent in the prevention of reserpine ptosis test in mice, with an ED50 of 0.5 mg/kg ip.     

Synthesis of certain substituted quinoxalines as antimicrobial agents (part II)

Several fused triazolo and ditriazoloquinoxaline derivatives such as 1-aryl-4-chloro-[1,2,4]triazolo[4,3-a]quinoxalines (3a-d), 4-alkoxy[1,2,4]triazolo[4,3-a]quinoxalines (4a,b), 4-substituted-amino-[1,2,4] triazolo[4,3-a]quinoxalines (5a-h), 1-(aryl)-[1,2,4]triazolo[4,3-a]quinoxalin-4(5H)-thione (6), 4-(arylidenehydrazino)1-phenyl-[1,2,4]triazolo[4,3-a]quinoxalines (10a-e) and [1,2,4]ditriazolo[4,3-a:3',4'-c]quinoxaline derivatives (11-13) have been synthesized and some of these derivatives were evaluated for antimicrobial and antifungal activity in vitro. It was found that compounds 3a and 9b possess potent antibacterial activity compared to the standard tetracycline.     

(2R)-4-oxo-4-[3-(trifluoromethyl)-5,6-dihydro[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl]-1-(2,4,5-trifluorophenyl)butan-2-amine: a potent, orally active dipeptidyl peptidase IV inhibitor for the treatment of type 2 diabetes

A novel series of beta-amino amides incorporating fused heterocycles, i.e., triazolopiperazines, were synthesized and evaluated as inhibitors of dipeptidyl peptidase IV (DPP-IV) for the treatment of type 2 diabetes. (2R)-4-Oxo-4-[3-(trifluoromethyl)-5,6-dihydro[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl]-1-(2,4,5-trifluorophenyl)butan-2-amine (1) is a potent, orally active DPP-IV inhibitor (IC(50) = 18 nM) with excellent selectivity over other proline-selective peptidases, oral bioavailability in preclinical species, and in vivo efficacy in animal models. MK-0431, the phosphate salt of compound 1, was selected for development as a potential new treatment for type 2 diabetes.     

Cardiotonic agents. 6. Synthesis and inotropic activity of 2,4-dihydro-5-[4-(1H-imidazol-1-yl)phenyl]-3H-pyrazol-3-ones: ring-contracted analogues of imazodan (CI-914)

A series of 2,4-dihydro-5-[4-(1H-imidazol-1-yl)phenyl]-3H-pyrazol-3-ones was synthesized and evaluated for positive inotropic activity. Only compounds with two small alkyl groups at C-4 showed significant activity. The structure-activity relationships for optimal inotropic activity are presented and compared with those of the 4,5-dihydro-3(2H)-pyridazinone series. The phosphodiesterase inhibitory activity is also reported and correlated with the substitution pattern at C-4 in the pyrazolone ring.     

Synthesis of thiazolo[4,5-d]pyrimidine derivatives as potential antimicrobial agents

In this study, we report the synthesis and antimicrobial evaluation of several new thiazolo[4,5-d]pyrimidine derivatives, namely 7-substituted amino-5-methyl-3-phenylthiazolo[4,5-d]pyrimidine-2(3H)-thiones 4a-e, 8, 13, 15, ethyl 2-cyano-2-(7-substituted-5-methyl-3-phenylthiazolo [4,5-d]-pyrimidin-2(3H)-ylidene)acetates 5a-b, 2-(7-substituted-5-methyl-3-phenylthiazolo[4,5-d]pyrimidin-2(3H)-ylidene)malononitriles 6a-b, 5-methyl-7-morpholino-3-phenylthiazolo[4,5-d] pyrimidine-2(3H)-one 7, and 7-[4-(1-substituted-5-phenyl-4,5-dihydro-1H-pyrazolin-3-yl)anilino]-5-methyl-3-phenylthiazolo[4,5-d]pyrimidine-2(3H)-thiones 10-12. Some of the tested compounds were more active against C. albicans than E. coil and P. aeruginosa, and all were inactive against S. aureus.