Amino Derivatives of Diaryl Pyrimidines and Azolopyrimidines as Protective Agents against LPS-Induced Acute Lung Injury.

The problem of lung damage originating from excessive inflammation and cytokine release during various types of infections remains relevant and stimulates the search for highly effective and safe drugs. The biological activity of the latter may be associated with the regulation of hyperactivation of certain immune cells and enzymes. Here, we propose the design and synthesis of amino derivatives of 4,6- and 5,7-diaryl substituted pyrimidines and [1,2,4]triazolo[1,5-a]pyrimidines as promising double-acting pharmacophores inhibiting IL-6 and NO. The anti-inflammatory activity of 14 target compounds was studied on isolated primary murine macrophages after LPS stimulation. Seven compounds were identified to inhibit the synthesis of nitric oxide and interleukin 6 at a concentration of 100 µM. The most active compounds are micromolar inhibitors of IL-6 secretion and NO synthesis, showing a minimal impact on innate immunity, unlike the reference drug dexamethasone, along with acceptable cytotoxicity. Evaluation in an animal model of acute lung injury proved the protective activity of compound 6e, which was supported by biochemical, cytological and morphological markers.

Guanidine Derivatives of Quinazoline-2,4(1H,3H)-Dione as NHE-1 Inhibitors and Anti-Inflammatory Agents.

Quinazolines are a rich source of bioactive compounds. Previously, we showed NHE-1 inhibitory, anti-inflammatory, antiplatelet, intraocular pressure lowering, and antiglycating activity for a series of quinazoline-2,4(1H,3H)-diones and quinazoline-4(3H)-one guanidine derivatives. In the present work, novel N1,N3-bis-substituted quinazoline-2,4(1H,3H)-dione derivatives bearing two guanidine moieties were synthesized and pharmacologically profiled. The most potent NHE-1 inhibitor 3a also possesses antiplatelet and intraocular-pressure-reducing activity. Compound 4a inhibits NO synthesis and IL-6 secretion in murine macrophages without immunotoxicity and alleviates neutrophil infiltration, edema, and tissue lesions in a model of LPS-induced acute lung injury. Hence, we considered quinazoline derivative 4a as a potential agent for suppression of cytokine-mediated inflammatory response and acute lung injury.

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.

Azolo[1,5-a]pyrimidines and Their Condensed Analogs with Anticoagulant Activity.

Hypercytokinemia, or cytokine storm, is one of the severe complications of viral and bacterial infections, involving the release of abnormal amounts of cytokines, resulting in a massive inflammatory response. Cytokine storm is associated with COVID-19 and sepsis high mortality rate by developing epithelial dysfunction and coagulopathy, leading to thromboembolism and multiple organ dysfunction syndrome. Anticoagulant therapy is an important tactic to prevent thrombosis in sepsis and COVID-19, but recent data show the incompatibility of modern direct oral anticoagulants and antiviral agents. It seems relevant to develop dual-action drugs with antiviral and anticoagulant properties. At the same time, it was shown that azolo[1,5-a]pyrimidines are heterocycles with a broad spectrum of antiviral activity. We have synthesized a new family of azolo[1,5-a]pyrimidines and their condensed polycyclic analogs by cyclocondensation reactions and direct CH-functionalization and studied their anticoagulant properties. Five compounds among 1,2,4-triazolo[1,5-a]pyrimidin-7-ones and 5-alkyl-1,3,4-thiadiazolo[3,2-a]purin-8-ones demonstrated higher anticoagulant activity than the reference drug, dabigatran etexilate. Antithrombin activity of most active compounds was confirmed using lipopolysaccharide (LPS)-treated blood to mimic the conditions of cytokine release syndrome. The studied compounds affected only the thrombin time value, reliably increasing it 6.5-15.2 times as compared to LPS-treated blood.

Synthesis and multifaceted pharmacological activity of novel quinazoline NHE-1 inhibitors.

The Na+/H+ exchanger isoform 1 (NHE-1) attracts ongoing attention as a validated drug target for the management of cardiovascular and ocular diseases owing to cytoprotective, anti-ischemic and anti-inflammatory properties of NHE-1 inhibitors. Herein we report novel NHE-1 inhibitors realized via functionalization of N1-alkyl quinazoline-2,4(1H,3H)-dione and quinazoline-4(3H)-one with N-acylguanidine or 3-acyl(5-amino-1,2,4-triazole) side chain. Lead compounds show activity in a nanomolar range. Their pharmacophoric features were elucidated with neural network modeling. Several compounds combine NHE-1 inhibition with antiplatelet activity. Compound 6b reduces intraocular pressure in rats and effectively inhibits the formation of glycated proteins. Compounds 3e and 3i inhibit pro-inflammatory activation of murine macrophages, LPS-induced interleukin-6 secretion and also exhibit antidepressant activity similar to amiloride. Hence, novel compounds represent an interesting starting point for the development of agents against cardiovascular diseases, thrombotic events, excessive inflammation, long-term diabetic complications and glaucoma.