7-Alkylamino-6-nitrotetrazolo[1,5-a]pyrimidines as precursors of anomalous nucleosides and heterocycles with potential antiseptic activity

The Effects of Nitroazolopyrimidines on the A1 Adenosine Receptor and Intraocular Pressure in Rats

Abstract

Six compounds of the 5(7)-alkylamino-6-nitroazolopyrimidine and 8-alkylazolo[5,1-b]purine series were selected based on the structural analysis of A1 adenosine receptor inhibitors and the role of this biological target in the modulation of intraocular pressure, an important factor in the pathogenesis of glaucoma. These heterocycles were shown to exhibit a weak affinity towards the A1 adenosine receptor on an in vitro model of the adenosine-dependent change of the chronotropic effect on isolated atria of white mice. On the other hand, thiadiazolo[3,2-a]pyrimidines and triazolo[5,1-b]purine displayed an in vivo hypotensive effect in rats. The leading compound, 5-methyl-8-(hydroxyethyl)triazolo[5,1-b]purine) (0.2% solution), caused a 34% reduction of ophthalmotonus in 3 h without an adverse resorptive effect. In addition, using the MTT-test it was shown on the human HepG2 cell line that the heterocycles affecting the intraocular pressure were by one to two orders of magnitude less cytotoxic than the reference doxorubicin.

Searching for novel antagonists of adenosine A1 receptors among azolo[1,5-a]pyrimidine nitro derivatives

Introduction: Ligands of adenosine A1Rs are potential candidates for the development of drugs for the treatment of paroxysmal supraventricular tachycardia, angina pectoris, hypertriglyceridemia, type 2 diabetes mellitus, neuropathic pain, and heart failure. At the same time, there is a deficiency of drugs that can regulate the functions of A1 receptors. A number of A1-antagonists are at the various stages of clinical trials; other drugs are not very selective or are characterized by an insufficient breadth of their therapeutic action. Therefore, the search for new medicinal compounds for the prevention and treatment of A1-depended diseases among nitro derivatives of tetrazolo[1,5-a]pyrimidine and 1,2,4-triazolo[1,5-a]pyrimidine is of scientific interest.

Materials and methods: The search for active compounds was carried out by in silico and in vitro methods. At the first stage, a computer forecast of A1-antagonistic activity was carried out using the Microcosm BioS software. At the second stage, the prediction results were verified in vitro in a model of isolated mouse atria.

Results and discussion: Based on the results of the prediction by the method of maximum similarity to standards, the most active compounds III, VIII, and XVII were selected. After testing the prediction results by the isolated atria method, the compound VIII was characterized by A1-blocking effect in vitro at a concentration of 10 μmol/L.

Conclusion: The most promising compound with A1-blocking effect in vitro was identified; it is a derivative of tetrazolo[1,5-a]pyrimidine under the code of VIII. It is of interest for us for further in-depth study of its pharmacological properties.

Discovery of Nitro-azolo[1,5-a]pyrimidines with Anti-Inflammatory and Protective Activity against LPS-Induced Acute Lung Injury

Acute lung injury remains a challenging clinical condition, necessitating the development of novel, safe and efficient treatments. The prevention of macrophage M1-polarization is a viable venue to tackle excessive inflammation. We performed a phenotypic screening campaign to identify azolopyrimidine compounds that effectively inhibit LPS-induced NO synthesis and interleukin 6 (IL-6) secretion. We identified lead compound 9g that inhibits IL-6 secretion with IC₅₀ of 3.72 µM without apparent cytotoxicity and with minimal suppression of macrophage phagocytosis in contrast to dexamethasone. In a mouse model of LPS-induced acute lung injury, 30 mg/kg i.p. 9g ameliorated anxiety-like behavior, inhibited IL-6 release, and limited neutrophil infiltration and pulmonary edema. A histological study confirmed the protective activity of 9g. Treatment with compound 9g prevented the migration of CD68⁺ macrophages and the incidence of hemorrhage. Hence, we have identified a promising pharmacological approach for the treatment of acute lung injury that may hold promise for the development of novel drugs against cytokine-mediated complications of bacterial and viral infections.

Pyrimido[1,2-a]benzimidazoles: synthesis and perspective of their pharmacological use

The review presents data on the synthesis as well as studies of biological activity of new derivatives of pyrimido[1,2-a]benzimidazoles published over the last decade. The bibliography of the review includes 136 sources.