Carboxyl-containing quinazolines and related heterocycles as carriers of anti-inflammatory activity

Abstract

Active pharmaceutical ingredients whose structure combines aromatic or heterocyclic fragments with pharmacophore carboxylic group are widespread on pharmaceutical market. The isolation of COX-NSAIDs complexes and following X-ray studies allowed to explain the key role of pharmacophore carboxylic group in the formation of enzyme-ligand interactions and the effect of its presence on the activity and selectivity. The introduction of selective COX-2-inhibitors to medicinal practice resulted in a significant decrease of side effects and complication frequencies. However, the problem of NSAIDs toxicity has not been solved. Thus, the search for the novel anti-inflammatory drugs using in silico methods and approaches including structural modification of known NSAIDs by “bioisosteric” replacements of aromatic and heterocyclic fragments with other structural elements with carboxylic group as the carrier of pharmacological effect, is a current trend of medicinal chemistry.

The aim of present study is to purposefully search for anti-inflammatory agents among carboxyl-containing quinazolines and related heterocycles using in silico and in vivo methods, as well as to evaluate carboxylic group effect on the level of anti-inflammatory activity.

Materials and methods. Quinazoline-4(3H)-ylidene)hydrazides of mono-(di-)carboxylic acids, 2-R-[1,2,4]triazolo[1,5-c]quinazolines, 3-R-5-(2-aminophenyl)-1H-1,2,4-triazoles, 5-carboxyalkyl[1,2,4]triazolo[1,5-c]quinazolines and 2-R-7-oxo-6,7-dihydropyrrolo[1,2-a][1,2,4]triazolo[1,5-c]quinazoline-4a(5H)-carboxylic acids were screened for their anti-inflammatory activity. MarvinSketch 20.19.0, AutoDock Vina and AutoDockTools 1.5.6, HyperChem 7.5, Discovery Studio were used for in silico research. “Drug-like” characteristics were evaluated using an online service. Prediction of toxicity and Ames mutagenicity of the studied compounds were performed in silico using Test software. Evaluation of the anti-inflammatory activity of the synthesized compounds was carried out on white Wistar rats (150–160 g of weight) using carrageenan induced paw edema model. Phlogogen (1 % aqueous solution of λ-carrageenan) was subplantarly injected in the dose of 0.1 ml in the rats’ hind right paw. The left one was used as a control. The studied compounds were intragastrically administered with atraumatic probe as water solution or finely dispersed suspension stabilized by Tween-80 in the dose of 10 mg/kg 1 hour before the injection of phlogogen. The reference drug Diclofenac sodium was administered intragastrically in a recommended for pre-clinical studies dose of 8 mg/kg. The paw volume was measured before the experiment and in 4 hours after phlogogen injection. The activity of these substances was determined by their ability to reduce the swelling compared with control group and was expressed in percentage. The experiments were carried out with respect to Bioethical rules and norms.

Results. The search for anti-inflammatory agents among carboxylic-containing quinazolines and related heterocycles was theoretically substantiated using results of molecular docking, druglike criteria calculations and predicted parameters of toxicity. Experimental in vivo methods (“carrageenan” test) confirmed the anti-inflammatory activity of studied compounds and showed that (quinazoline-4(3H)-ylidene)hydrazides of dicarboxylic acids inhibit edema by 17.0–50.0 %, 2-carboxyalkyl-(phenyl-)-[1,2,4]triazolo[1,5-c]quinazolines – by 0.00–40.63 %, 2-(5-(2-aminophenyl)-1H-1,2,4-triazol-3-yl)alkyl-(phenyl-)carboxylic acids – by 2.43–49.65 %, 2-R-5-carboxyalkyl[1,2,4]triazolo[1,5-c]quinazolines – by 0.47–22.93 % and 2-R-7-oxo-6,7-dihydropyrrolo[1,2-a][1,2,4]triazolo[1,5-c]quinazoline-4a(5H)-carboxylic acids – by 0.94–17.16 %. Among them, there are compounds that compete with the reference drug “Diclofenac sodium”. The SAR analysis showed that both conformation of the molecule and the nature of the “pharmacophore” moiety (carboxyalkyl residue length) at the corresponding positions of the heterocycle have a significant effect on the anti-inflammatory activity. It was shown that the test compounds, according to molecular docking visualization data, have other enzyme-ligand interactions and probably a different mechanism of activity.

Conclusions. The predicted affinity values, calculated “drug-like” criteria and toxicity parameters, visualization of the docking of studied molecules in active site of biological targets as well as experimental studies results showed that investigated compounds are promising in scope of purposeful search for anti-inflammatory drugs. The conducted in vivo screening of anti-inflammatory activity among carboxyl-containing quinazolines and related heterocyclic compounds allowed to detect series of substances that by the level of anti-inflammatory activity compete with reference-compound “Diclofenac sodium” on the carrageenan-induced paw edema model. Presented data may be considered as a theoretical basis for further structural modification of studied compounds aimed on elaboration of novel anti-inflammatory agents and evaluation of their activity mechanism (lipoxygenase inhibitors, phospholipase inhibitors, etc.).