A3 receptors in cortical neurons: Pharmacological aspects and neuroprotection during hypoxia

A one-pot synthetic approach for the construction of a thiazolo[3,2-a]benzimidazole-linked quinazoline scaffoldviapalladium-catalyzed reactions

4-(2-Substituted-[1,3]thiazolo[3,2-a]benzimidazol-3-yl)quinazolin-2-amines were prepared by the reaction of 2,4-dichloroquinazoline, terminal alkynes, secondary amines, and 1H-benzo[d]imidazole-2(3H)-thione in the presence of palladium catalyst.

Metal-free sequential decarbonylative annulation of N-cyanamides for the construction of 2,3-dihydropyrrolo[2,1-b]quinazolin-9(1H)-ones

A convenient metal-free sequential decarbonylative annulation of unactivated alkenes for the construction of quinazolinones and dihydroisoquinolinones has been developed.

One-pot three-component synthesis of quinazolines via a copper-catalysed oxidative amination reaction

A copper-catalysed three-component reaction for constructing a series of quinazoline derivatives has been developed.

Synthetic approaches, functionalization and therapeutic potential of quinazoline and quinazolinone skeletons: the advances continue

The presence of N-heterocycles as an essential structural motif in a variety of biologically active substances has stimulated the development of new strategies and technologies for their synthesis. Among the various N-heterocyclic scaffolds, quinazolines and quinazolinones form a privileged class of compounds with their diverse spectrum of therapeutic potential. The easy generation of complex molecular diversity through broadly applicable, cost-effective, practical and sustainable synthetic methods in a straightforward fashion along with the importance of these motifs in medicinal chemistry, received significant attention from researchers engaged in drug design and heterocyclic methodology development. In this perspective, the current review article is an effort to recapitulate recent developments in the eco-friendly and green procedures for the construction of highly challenging and potentially bioactive quinazoline and quinazolinone compounds in order to help medicinal chemists in designing and synthesizing novel and potent compounds for the treatment of different disorders. The key mechanistic insights for the synthesis of these heterocycles along with potential applications and manipulations of the products have also been conferred. This article also aims to highlight the promising future directions for the easy access to these frameworks in addition to the identification of more potent and specific products for numerous biological targets.

CuCl/DABCO/4-HO-TEMPO-catalyzed aerobic oxidative synthesis of 2-substituted quinazolines and 4H-3,1-benzoxazines

The Cu/N-ligand/TEMPO catalytic system was first applied to the aerobic oxidative synthesis of heterocycles. As demonstrated, 2-substituted quinazolines and 4H-3,1-benzoxazines were synthesized efficiently from the one-pot reaction of aldehydes with 2-aminobenzylamines and 2-aminobenzyl alcohols, respectively, by employing CuCl/DABCO/4-HO-TEMPO as the catalysts and oxygen as the terminal oxidant.

Saffron extract and trans-crocetin inhibit glutamatergic synaptic transmission in rat cortical brain slices

Saffron, the dried stigmata of Crocus sativus L., is used in traditional medicine for a wide range of indications including cramps, asthma, and depression. To investigate the influence of hydro-ethanolic saffron extract (CSE) and trans-crocetin on synaptic transmission, postsynaptic potentials (PSPs) were elicited by focal electrical stimulation and recorded using intracellular placed microelectrodes in pyramidal cells from rat cingulate cortex. CSE (10-200 μg/ml) inhibited evoked PSPs as well as the isolated NMDA and non-NMDA component of PSPs. Glutamate (500 μM) added into the organ bath induced membrane depolarization. CSE decreased glutamate-induced membrane depolarization. Additionally, CSE at 100 μg/ml decreased NMDA (20 μM) and kainate (1 μM)-induced depolarization, whereas AMPA (1 μM)-induced depolarization was not affected. Trans-crocetin (1-50 μM) showed inhibition of evoked PSPs and glutamate-induced membrane depolarization comparable to CSE. Trans-crocetin at 10 μM decreased NMDA (20 μM)-induced membrane depolarization, but did not inhibit the isolated non-NMDA component of PSPs. We conclude that trans-crocetin is involved in the antagonistic effect of CSE on NMDA but not on kainate receptors.

Copper-catalyzed cascade synthesis of benzimidazoquinazoline derivatives under mild condition

An efficient copper-catalyzed cascade method has been developed for the synthesis of benzimidazoquinazoline derivatives via reactions of readily available substituted 2-(2-halophenyl)benzoimidazoles with amidines or guanidine under mild conditions (even at room temperature).

A3 adenosine receptor: pharmacology and role in disease

The study of the A(3) adenosine receptor (A(3)AR) represents a rapidly growing and intense area of research in the adenosine field. The present chapter will provide an overview of the expression patterns, molecular pharmacology and functional role of this A(3)AR subtype under pathophysiological conditions. Through studies utilizing selective A(3)AR agonists and antagonists, or A(3)AR knockout mice, it is now clear that this receptor plays a critical role in the modulation of ischemic diseases as well as in inflammatory and autoimmune pathologies. Therefore, the potential therapeutic use of agonists and antagonists will also be described. The discussion will principally address the use of such compounds in the treatment of brain and heart ischemia, asthma, sepsis and glaucoma. The final part concentrates on the molecular basis of A(3)ARs in autoimmune diseases such as rheumatoid arthritis, and includes a description of clinical trials with the selective agonist CF101. Based on this chapter, it is evident that continued research to discover agonists and antagonists for the A(3)AR subtype is warranted.

Highly efficient copper-catalyzed cascade synthesis of quinazoline and quinazolinone derivatives

We have developed a general and highly efficient copper-catalyzed method for synthesis of quinazoline and quinazolinone derivatives, the target products were obtained in good to excellent yields via cascade reactions of amidine hydrochlorides with substituted 2-halobenzaldehydes, 2-halophenylketones, or methyl 2-halobenzoates, and the method is of simple, economical and practical advantages.

The A3 adenosine receptor: an enigmatic player in cell biology

Adenosine is a primordial signaling molecule present in every cell of the human body that mediates its physiological functions by interacting with 4 subtypes of G-protein-coupled receptors, termed A1, A2A, A2B and A3. The A3 subtype is perhaps the most enigmatic among adenosine receptors since, although several studies have been performed in the years to elucidate its physiological function, it still presents in several cases a double nature in different pathophysiological conditions. The 2 personalities of A3 often come into direct conflict, e.g., in ischemia, inflammation and cancer, rendering this receptor as a single entity behaving in 2 different ways. This review focuses on the most relevant aspects of A3 adenosine subtype activation and summarizes the pharmacological evidence as the basis of the dichotomy of this receptor in different therapeutic fields. Although much is still to be learned about the function of the A3 receptor and in spite of its duality, at the present time it can be speculated that A3 receptor selective ligands might show utility in the treatment of ischemic conditions, glaucoma, asthma, arthritis, cancer and other disorders in which inflammation is a feature. The biggest and most intriguing challenge for the future is therefore to understand whether and where selective A3 agonists or antagonists are the best choice.

Exploring QSAR of thiazole and thiadiazole derivatives as potent and selective human adenosine A3 receptor antagonists using FA and GFA techniques

Binding affinity data of thiazole and thiadiazole derivatives (n=30) for human adenosine A3 receptor subtype have been subjected to Quantitative Structure-Activity Relationship (QSAR) analysis using quantum chemical and hydrophobicity parameters. Wang-Ford charges of the common atoms of the compounds [calculated from molecular electrostatic potential surface of energy minimized geometry using Austin Model 1 (AM1) technique] were used as independent variables apart from partition coefficient (logP) and suitable dummy parameters. The variables for the multiple regression analyses were selected based on principal component factor analysis (FA), and generated equations were statistically validated using leave-one-out technique. The best equation thus obtained explained and predicted 74.4% and 68.9% respectively of the variance of the binding affinity. The results suggested importance of Wang-Ford charges of atoms C2, C5 and C7. Furthermore, the A3 binding affinity increases with decrease of lipophilicity of the compounds and in the presence of methyl or ethyl substituent at R position. Again, the binding affinity decreases in the presence of tert-butyloxy group at R position. When factor scores were used as predictor variables in principal component regression analysis, the resulted model showed 87.0% predicted variance and 89.5% explained variance. The data set was also modeled using genetic function approximation (GFA) technique. The best two equations derived from GFA show better predicted variance values (0.753 and 0.739) than that found in case of the best equation derived from FA. However, considerable intercorrelation was found between two predictor variables in case of GFA derived equations. GFA derived equations show importance of Wang-Ford charges of different atoms of the thiazole/thiadiazole nucleus and phenyl ring (S9, X8 and C2, the effects of the first two being predominant) along with similar impact of lipophilicity and R group on the binding affinity as found in case of the FA derived relation.