The perspectives of synthetic aducts (salts) of Nitroxoline^TM and 2-Aminoquinolin-8-ol as promising antibacterial agents.

The threatening phenomenon of antibiotic failure in the future determines the intensive research of antibacterial active compounds to be promising candidates as antibiotics. Quinolines with only representative in clinical practice – Nitroxoline^TM are, in addition to successful beta-lactams, macrolides, tetracyclines and other antibiotic categories forgotten antibiotics. The perspective the antibacterial efficiency of Nitroxoline^TM and 2-aminoquinolin-8-ol on eight selected, the most problematic, highly resistant bacterial species (Klebsiella ssp., Enterococcus ssp., Pseudomonas aeruginosa, Acinetobacter baumannii and Staphylococcus aureus) could lead to higher solubility and thus bioavailability and increasing of antibacterial effect. In the first phase, basic salts of Nitroxoline^TM with sodium hydroxide, benzylamine, 4-(aminomethyl)pyridine and other primary amines were synthesized. Within the second phase, opposite acidic salts of 2-aminoquinolin-8-ol were synthesized with following acids: oxalic acid, pyrazine-2,3-dicarboxylic acid, chelidonic acid, quinaldic acid, 3,5-dinitrosalycilic acid, pyridine-3,4-dicarboxylic acid, quinoline-2-carboxylic acid, quinoline-3-carboxylic acid, kynurenic acid, xanthurenic. Nitroxoline^TM and 2-aminoquinolin-8-ol both expressed flat antibacterial effect with average value on eight mentioned bacterial strains: 6,1 mg/L (32 mM), respectively 14,2 mg/L (88 mM). The synthetized salts of both quinolinols expressed significantly higher solubility and slightly increased antibacterial activity. The identity and purity of prepared products were determined by NMR and IR spectroscopy. The MW values of both quinolinols are relatively low and offer better use of the largest molecule limit, defined by Lipinski´s rule of five at 500 g/M. The options of the choice of amines or acids offers the achievement of quarternary salts with improved antibacterial activity.