Synthesis of novel D-ring fused 7'-aryl-androstano[17,16-d][1,2,4] triazolo[1,5-a]pyrimidines

The preparation of novel steroidal heterocycles containing the 7-aryl-substituted 1,2,4-triazolo[1,5-a]pyrimidine moiety fused to the 16,17-positions of the steroid nucleus is described. The Aldol reaction of 4-aza-androst-3,17-dione (1a) and dehydroepiandrosterone (DHEA, 1b) with aromatic aldehydes was catalyzed by KF/Al(2)O(3) to give the corresponding 3-oxo-4-aza-5α- and 3β-hydroxy-5-en-16-arylidene-17-ketosteroids (2a-r). Subsequently, the intermediates 2a-r reacted with dinucleophilic 3-amino-1,2,4-triazole in presence of t-BuOK to afford the title compounds (3a-r). All the synthesized heterosteroids are new and are currently being evaluated for their biological activities.     

Chlorotrimethylsilane-promoted one-pot synthesis of steroidal[17,16-d]pyrimidines

A novel and practical procedure was developed for the preparation of steroidal[17,16-d]pyrimidines by chlorotrimethylsilane (TMSCl)-promoted one-pot multicomponent Biginelli-like condensations of steroid-17-ones, urea and aromatic aldehydes. First, treatment of the steroid-17-ones with urea and aromatic aldehydes in dimethylformamide (DMF)/acetonitrile (ACN) gives the corresponding Biginelli products, following the aromatising reaction of the Biginelli products at the same time under air to yield the desired steroidal[17,16-d]pyrimidines (78-88%). Since steroidal[17,16-d]pyrimidines with hydroxyl group can be subsequently converted into steroidal[17,16-d]pyrimidine derivatives, this general method provides a highly efficient route to these biologically important compounds.     

Synthesis,modeling and biological evaluation of some pyrazolo[3,4-d]pyrimidinones and pyrazolo[4,3-e][1,2,4]triazolo[4,3-a]pyrimidinones as anti-inflammatory agents

New pyrazolo[3,4-d]pyrimidinone and pyrazolo[4,3-e][1,2,4]triazolo[4,3-a]pyrimidinone derivatives were synthesized. They have been evaluated for their anti-inflammatory activity using in vitro (COX-1/COX-2) inhibitory assay. Moreover, compounds with promising in vitro activity and COX-1/COX-2 selectivity indices were subjected for in vivo anti-inflammatory testing using formalin induced paw edema and cotton-pellet induced granuloma assays for acute and chronic models, respectively. Compounds (2c, 3i, 6a, 8 and 12) showed promising COX-2 inhibitory activity and high selectivity compared to celecoxib. Most of the compounds exhibited potential anti-inflammatory activity for both in vivo acute and chronic models. Almost all compounds displayed safe gastrointestinal profile and low ulcerogenic potential guided by histopathological examination. Furthermore, molecular docking experiments rationalized the observed in vitro anti-inflammatory activity of selected candidates. In silico predictions of the pharmacokinetic and drug-likeness properties recommended accepted profiles of the majority of compounds. In conclusion, this work provides an extension of the chemical space of pyrazolopyrimidinone and pyrazolotriazolopyrimidinone chemotypes for the anti-inflammatory activity.     

Pyrrolo- and pyrazolo-[3,4-e][1,2,4]triazolo[1,5-c]pyrimidines as adenosine receptor antagonists

The discovery and development of adenosine receptor antagonists have represented for years an attractive field of research from the perspective of identifying new drugs for the treatment of widespread disorders such as inflammation, asthma and Parkinson's disease. The present work can be considered as an extension of our structure-activity relationship studies on the pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidine (PTP) nucleus, extensively investigated by us as a useful template, in particular, for the identification of A(2A) and A(3) adenosine receptor antagonists. In order to explore the role of the nitrogen at the 7-position, we performed a new synthetic strategy for the preparation of pyrrolo[3,4-e][1,2,4]triazolo[1,5-c]pyrimidine derivatives which can be considered as 7-deaza analogues of the parent PTPs. We also synthesised a novel series of pyrazolo[3,4-e][1,2,4]triazolo[1,5-c]pyrimidines as junction isomers of the reference compounds. In both cases we obtained some examples of potent antagonists (K(i) in the low nanomolar range) with variable selectivity profiles in relation to the nature of substituents introduced at the C(5)-, N(8)- and/or N(9)-positions. The pyrrolo-triazolo-pyrimidine derivative 9b appeared to be a potent A(3) adenosine receptor antagonist (K(i)=10 nM) with good selectivity over hA(1) (74-fold) and hA(2A) (20-fold) adenosine receptors combined with low activity at the hA(2B) subtype (IC(50)=906 nM). Moreover, some examples of high-affinity A(1)/A(2A) dual antagonists have been identified in both series. This work constitutes a new and important contribution for the comprehension of the interaction between PTPs and adenosine receptors.     

Tyrosine kinase inhibition effects of novel Pyrazolo[1,5-a]pyrimidines and Pyrido[2,3-d]pyrimidines ligand: Synthesis,biological screening and molecular modeling studies

Tyrosine kinases are one of the most critical mediators in the signaling path way. Late studies have proved the part of tyrosine kinases in the pathophysiology of cancer diseases. This current research paper has focused on investigating the novel Pyrazolo[1,5-a]pyrimidines and Pyrido[2,3-d]pyrimidines as a small molecules that can inhibit tyrosine kinase in cancer cells. NCI protocol was applied to test the antitumor activity of such compounds. Leukemia and renal cancer cell lines proved to be sensitive to some derivatives such as 6b–d, 9a and 11 with GI% values ranging from 30.4 to 41.3%. In addition, compound 11 proved to be the most active against MCF-7 with GI% 62.5. The synthesized compounds were also evaluated for their inhibitory effects against EGFR kinase enzyme. Compound 9b proved to be the most active one among the synthesized series with inhibition % value of 81.72 at 25 nM concentration and IC₅₀ 8.4 nM which is very close to the reference drug Sorafenib. In vitro cytotoxicity test was also performed using the MCF-7 breast cell line. Computer modeling using the active site of tyrosine kinase as a template and the most active tyrosine kinase inhibitors were calculated. Docking studies of the synthesized compounds into the active site of EGFR kinase domain showed good agreement with the obtained biological results.     

Synthesis,anti-thymidine phosphorylase activity and molecular docking of 5-thioxo-[1,2,4]triazolo[1,5-a][1,3,5]triazin-7-ones

In our lead finding program, a series of 5-thioxo-[1,2,4]triazolo[1,5-a][1,3,5]triazin-7-ones and their 5-thio-alkyl derivatives were designed and synthesized which contained different substituents at ortho-position of 2-phenyl ring attached to the fused ring structure. The preliminary pharmacological evaluation demonstrated that the synthesized compounds exhibited a varying degree of inhibitory activity towards thymidine phosphorylase (TP), comparable to reference compound, 7-Deazaxanthine (7-DX, 2) (IC₅₀ value = 42.63 μM). The study also inferred that the ortho-substituted group at the phenyl ring and 5-thio-alkyl moiety imparted steric hindrance effects in the binding site of the enzyme, leading to a reduced inhibitory response. In addition, compound 3a was identified as a mixed-type inhibitor of TP. Moreover, computational docking study was performed to illustrate the important structural information on the plausible ligand-enzyme binding interactions.     

Synthesis and biological evaluation of new [1,2,4]triazolo[4,3-a]pyridine derivatives as potential c-Met inhibitors

A series of [1,2,4]triazolo[4,3-a]pyrazine derivatives (4a–4i) were designed, synthesized and evaluated for their c-Met kinase inhibition and antitumor activity against SNU5 gastric cell line in vitro. Among these compounds, 4d was found to show the highest activity against c-Met and high selectivity against the tumor cells which are believed to be dependent on the c-Met oncogene amplification, because 4d selectively inhibited c-Met while had no effect on other 59 kinases. In vivo efficacy study on human gastric (MKN-45) and human non-small cell lung (NCI-H1993) tumor xenograft in nude mouse demonstrated that 4d·CH₃SO₃H had a better inhibiting activity than SGX-523 in a dose-dependent manner. When tested in mice, compound 4d·CH₃SO₃H was found to have biological half-lives and plasma exposure values higher than those of JNJ-38877605, and its long-term toxicity and acute toxicity turned out to be acceptable, all of which indicates that 4d·CH₃SO₃H is a desirable drug candidate.     

Synthesis of [1,2,4]triazolo[1,5-a]pyrazines as adenosine A2A receptor antagonists

Potent and selective antagonists of the adenosine A2A receptor often contain a nitrogen-rich fused-ring heterocyclic core. Replacement of the core with an isomeric ring system has previously been shown to improve target affinity, selectivity, and in vivo activity. This paper describes the preparation, by a novel route, of A2A receptor antagonists containing the [1,2,4]triazolo[1,5-a]pyrazine nucleus, which is isomeric with the [1,2,4]triazolo[1,5-c]pyrimidine core of a series of known A2A antagonists with in vivo activity in animal models of Parkinson's disease.     

2-Amino-[1,2,4]triazolo[1,5-a]pyridines as JAK2 inhibitors

The advancement of a series of ligand efficient 2-amino-[1,2,4]triazolo[1,5-a]pyridines, initially identified from high-throughput screening, to a JAK2 inhibitor with pharmacodynamic activity in a mouse xenograft model is disclosed.

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Discovery of imidazo[1,2-a]-, [1,2,4]triazolo[4,3-a]-, and [1,2,4]triazolo[1,5-a]pyridine-8-carboxamide negative allosteric modulators of metabotropic glutamate receptor subtype 5

Based on a hypothesis that an intramolecular hydrogen bond was present in our lead series of picolinamide mGlu₅ NAMs, we reasoned that an inactive nicotinamide series could be modified through introduction of a fused heterocyclic core to generate potent mGlu₅ NAMs. In this Letter, we describe the synthesis and evaluation of compounds that demonstrate the viability of that approach. Selected analogs were profiled in a variety of in vitro assays, and two compounds were evaluated in rat pharmacokinetic studies and a mouse model of obsessive-compulsive disorder. Ancillary pharmacology screening revealed that members of this series exhibited moderate inhibition of the dopamine transporter (DAT), and SAR was developed that expanded the selectivity for mGlu₅ versus DAT.     

Synthesis and biological study of 3-(phenylsulfonyl)thieno[2,3-e][1,2,3]triazolo[1,5-a]pyrimidines as potent and selective serotonin 5-HT6 receptor antagonists

A number of 3-(phenylsulfonyl)thieno[2,3-e][1,2,3]triazolo[1,5-a]pyrimidines were prepared and their 5-HT₆ receptor binding affinity and ability to inhibit the functional cellular responses to serotonin were evaluated. 3-[(3-Chlorophenyl)sulfonyl]-N-(tetrahydrofuran-2-ylmethyl)thieno[2,3-e][1,2,3]triazolo[1,5-a]pyrimidin-5-amine 2{5,26} appeared to be the most active in a functional assay (IC₅₀ = 29.0 nM) and 3-(phenylsulfonyl)-N-(2-thienylmethyl) thieno[2,3-e][1,2,3]triazolo[1,5-a]pyrimidin-5-amine 2{1,28} demonstrated the greatest affinity in a 5-HT₆ receptor radioligand binding assay (K_i = 1.7 nM). A screening of 5-HT_2A and 5-HT_2B receptor affinity revealed that 3-(phenylsulfonyl)thieno[2,3-e][1,2,3]triazolo[1,5-a]pyrimidines are highly selective 5-HT₆ receptor ligands.     

Synthesis,biological evaluation,and in silico studies of new CDK2 inhibitors based on pyrazolo[3,4-d]pyrimidine and pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidine scaffold with apoptotic activity

Cyclin-dependent kinase inhibition is considered a promising target for cancer treatment for its crucial role in cell cycle regulation. Pyrazolo pyrimidine derivatives were well established for their antitumor activity via CDK2 inhibition. In this research, new series of pyrazolopyrimidine derivatives (4–15) was designed and synthesised as novel CDK2 inhibitors. The anti-proliferative activities against MCF-7, HCT-116, and HepG-2 were used to evaluate their anticancer activity as novel CDK2 inhibitors. Most of the compounds showed superior cytotoxic activity against MCF-7 and HCT-116 compared to Sorafenib. Only compounds 8, 14, and 15 showed potent activity against HepG-2. The CDK2/cyclin A2 enzyme inhibitory activity was tested for all synthesised compounds. Compound 15 showed the most significant inhibitory activity with IC₅₀ 0.061 ± 0.003 µM. It exerted remarkable alteration in Pre G1 and S phase cell cycle progression and caused apoptosis in HCT cells. In addition, the normal cell line cytotoxicity for compound 15 was assigned revealing low cytotoxic results in normal cells rather than cancer cells. Molecular docking was achieved on the designed compounds and confirmed the two essential hydrogen binding with Leu83 in CDK2 active site. In silico ADMET studies and drug-likeness showed proper pharmacokinetic properties which helped in structure requirements prediction for the observed antitumor activity.     

Anticytokinin activity of 4-substituted triazolo[4,5-d]pyrimidines and 4-substituted pyrazolo[3,4-d]pyrimidines

The synthesis and physiological activity of some novel 4-substituted triazolo[4,5-d]pyrimidines and 4-substituted pyrazolo[3,4-d]pyrimidines are described. Most of the compounds possessed high anticytokinin activity towards purine (benzyladenine) and phenylurea (4-PU-30) type cytokinins. 1-Benzyl-4-ethoxycarbonylpiperazinyl-1H-1,2,3-triazolo[4,5-d]pyrimidine almost completely removed cytokinin stimulated effects—betacyanin synthesis in Amaranthus caudatus cotyledons; growth of radish cotyledons and retention of chlorophyll in leaf explants. Some chemical structurephysiological activity relationships have been established.     

Synthesis and anticonvulsant activity evaluation of 6-substituted-[1,2,4]triazolo[3,4-a](tetrazolo[5,1-a])phthalazine derivatives

With the aim of finding new anticonvulsant drugs, new 6-substituted-[1,2,4]triazolo[3,4-a] (tetrazolo[5,1-a]) phthalazine derivatives (1–34) have been designed and synthesized. All the compounds were evaluated for their anticonvulsant activities using the maximal electroshock test (MES). Most of the synthesized compounds exhibited potent anticonvulsant activities in the MES. The most promising compound 14 showed significant anticonvulsant activity in MES test with ED₅₀ value of 9.3 mg/kg. It displayed a wide margin of safety with protective index much higher than the standard drug Carbamazepine. And the potency of compound 14 against seizures induced by Pentylenetetrazole, Isoniazid, Thiosemicarbazide and 3-Mercaptopropionic acid in the chemical-induced seizure tests suggested that compound 14 displayed wide spectrum of activity in several models.     

The chemistry of [1,2,3]triazolo[1,5-a]pyridines

The reactivity of [1,2,3]triazolo[1,5-a]pyridines 1 is described. Triazolopyridines react with electrophiles in two contrasting ways, giving 3-substituted triazolopyridines 2, or products 3, resulting from triazolo ring opening with loss of molecular nitrogen. The triazolopyridines can be lithiated at -40 degrees C by lithium diisopropylamide in ether giving regiospecifically the 7-lithio derivative. Bromotriazolopyridines have activation towards nucleophilic substitution at position 5 and 7, and benzenoid inertness at position 6. The parent compound 1a is easily hydrogenated giving tetrahydrotriazolopyridine 11a in high yield; when the triazolopyridines have substituents, the hydrogenation reaction strongly depends on the position of the substituent. Triazolopyridinium ylides of type 18 and 26 react with acetylenic esters; these reactions are influenced by the nature of solvent and the acetylenic ester used, giving different types of adducts: stable disubstituted triazolopyridinium ylides of type 19 and 20, indolizines 21, or pyrroleninylpyrazolo[5,1-a] pyridines 22. Photochemistry, and photochemical reactions with MP and DMAD of these ylides are also described. A new way to 2,2'-bipyridines, in two steps from triazolopyridines is reported.     

Synthesis and positive inotropic evaluation of [1,2,4]triazolo[3,4-a]phthalazine and tetrazolo[5,1-a]phthalazine derivatives bearing substituted piperazine moieties

Four series of [1,2,4]triazolo[3,4-a]phthalazine and tetrazolo[5,1-a]phthalazine derivatives bearing substituted piperazine moieties were synthesized and evaluated for their positive inotropic activity by measuring the left atrium stroke volume in isolated rabbit-heart preparations. Several compounds were developed and showed favorable activities compared to the standard drug milrinone, with (4-([1,2,4]triazolo[3,4-a]phthalazin-6-yl)piperazin-1-yl)(p-tolyl)methanone (5g) being identified as the most potent with an increased stroke volume of 19.15 ± 0.22% (milrinone: 2.46 ± 0.07%) at a concentration of 3 × 10^–5 M. A preliminary study of mechanism of action revealed that 5g displayed its positive inotropic effect may be related to the PDE-cAMP-PKA signaling pathway. Compounds exhibiting inotropic effects were also evaluated in terms of the chronotropic effects.     

Synthesis of some new [1,2,4]triazolo[3,4-b][1,3,4]thiadiazines and [1,2,4]triazolo[3,4-b][1,3,4] thiadiazoles starting from 5-nitro-2-furoic acid and evaluation of their antimicrobial activity

New series of fused 1,2,4-triazoles such as, 6-(aryl)-3-(5-nitrofuran-2-yl)-5,6-dihydro-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles 4-8, 6-(alkyl/aryl amino)-3-(5-nitrofuran-2-yl)-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles 9-13 and 6-(4-substituted phenyl)-3-(5-nitrofuran-2-yl)-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazines 14-18 have been synthesized via the reaction of 4-amino-5-(5-nitrofuran-2-yl)-4H-1,2,4-triazole-3-thiol 3 with various reagents such as hetero aromatic aldehydes, alkyl/aryl isothiocyanates and 4-substituted phenacyl bromides, respectively. The structures of the newly synthesized compounds have been confirmed on the basis of elemental analysis and spectral studies. The newly synthesized triazolo derivatives have been investigated for their in vitro antibacterial activity. Most of the tested compounds showed interesting antibacterial activity against Staphylococcus aureus. Furthermore, the most potent antibacterial compounds 11-13 were evaluated for their in vitro cytotoxic activity against human cancer cell lines. It was found that compounds 11 and 13 showed higher cytotoxicity against Hep-G2 cell line as compared to standard.     

Design,synthesis and evaluation of photoactivatable derivatives of microtubule (MT)-active [1,2,4]triazolo[1,5-a]pyrimidines

The [1,2,4]triazolo[1,5-a]pyrimidines comprise a promising class of non-naturally occurring microtubule (MT)-active compounds. Prior studies revealed that different triazolopyrimidine substitutions can yield molecules that either promote MT stabilization or disrupt MT integrity. These differences can have important ramifications in the therapeutic applications of triazolopyrimidines and suggest that different analogues may exhibit different binding modes within the same site or possibly interact with tubulin/MTs at alternative binding sites. To help discern these possibilities, a series of photoactivatable triazolopyrimidine congeners was designed, synthesized and evaluated in cellular assays with the goal of identifying candidate probes for photoaffinity labeling experiments. These studies led to the identification of different derivatives that incorporate a diazirine ring in the amine substituent at position 7 of the triazolopyrimidine heterocycle, resulting in molecules that either promote stabilization of MTs or disrupt MT integrity. These photoactivatable candidate probes hold promise to investigate the mode of action of MT-active triazolopyrimidines.     

Design,synthesis, and evaluation of novel VEGFR2 kinase inhibitors: Discovery of [1,2,4]triazolo[1,5-a]pyridine derivatives with slow dissociation kinetics

For the purpose of discovering novel type-II inhibitors of vascular endothelial growth factor receptor 2 (VEGFR2) kinase, we designed and synthesized 5,6-fused heterocyclic compounds bearing a anilide group. A co-crystal structure analysis of imidazo[1,2-b]pyridazine derivative 2 with VEGFR2 revealed that the N1-nitrogen of imidazo[1,2-b]pyridazine core interacts with the backbone NH group of Cys919. To retain this essential interaction, we designed a series of imidazo[1,2-a]pyridine, [1,2,4]triazolo[1,5-a]pyridine, thiazolo[5,4-b]pyridine, and 1,3-benzothiazole derivatives maintaining a ring nitrogen as hydrogen bond acceptor (HBA) at the corresponding position. All compounds thus designed displayed strong inhibitory activity against VEGFR2 kinase, and the [1,2,4]triazolo[1,5-a]pyridine 13d displayed favorable physicochemical properties. Furthermore, 13d inhibited VEGFR2 kinase with slow dissociation kinetics and also inhibited platelet-derived growth factor receptor (PDGFR) kinases. Oral administration of 13d showed potent anti-tumor efficacy in DU145 and A549 xenograft models in nude mice.     

Synthesis and anticonvulsant activity of 7-alkoxyl-4,5-dihydro-[1,2,4]triazolo[4,3-a]quinolines

A series of 7-alkoxyl-4,5-dihydro-[1,2,4]triazolo[4,3-a]quinoline derivatives was synthesized using 6-hydroxy-3,4-dihydro-1H-quinolin-2-one as a starting material. Their anticonvulsant activities were evaluated by the maximal electroshock test (MES test) and the subcutaneous (s.c.) pentylenetetrazol test (scMet test), and their neurotoxicity was evaluated by the rotarod neurotoxicity test (Tox). MES and scMet tests show that 7-(4-fluorobenzyloxy)-4,5-dihydro-[1,2,4]triazolo[4,3-a]quinoline 4l was found to be the most potent with ED50 value of 11.8 and 6.7 mg kg(-1) and protective index (PI = TD50/ED50) value of 4.6 and 8.1, respectively.