Design synthesis and antibacterial activity studies of new thiadiazoloquinolone compounds

Abstract

New 9-(alkyl/aryl)-4-fluoro-6-oxo [1,2,5]thiadiazolo [3,4-h]quinoline-5-carboxylic acids and their esters were designed and synthesized. A detailed discussion of the reactions utilized in the preparation of the intermediate and target compounds is reported. All the newly synthesized compounds were fully characterized using all the physico-chemical means needed. All the intermediates and the final esters and acids were tested against bacterial and fungal strains. The acids 25a and 25c proved to be very active against Gram positive and Gram negative bacteria with MIC 0.15-3 mg/mL. The structure-activity relationship of antibacterial thiadiazoloquinolones shows that compounds 25a and 25c are twice less potent than the corresponding cyclopropyl derivative 16. Therefore, the cyclopropyl moiety on N-9 seems to be the most suitable substituent.

Quinolone derivatives and their antifungal activities: An overview

“…The Schiff bases and thiazolidinones of 1‐cyclopropyl‐6‐fluoro‐7‐[4‐(2,3‐dichlorophenyl)piperazin‐1‐yl]‐4‐quinolones 17–19 showed moderate‐to‐weak activities against A. niger , A. clavatus , and C. albicans with MIC values ranging from 100 to >1000 μg/ml . The SAR indicated that the antifungal activity of 17 , 18, and 19 (Figure ) was at the same level, suggesting the introduction of a basic nitrogen heterocycle at the C‐7 position could not increase the activity.…”

The crystal structure of 3-(1H-benzo[d]imidazol-2-yl)-7-chloro-1-cyclopropyl-6-fluoro-1,4-dihydroquinolin — dimethylsulfoxide (1/1), C21H19ClFN3O2S

“…Various derivatives prove to be very potent against bacterial and fungal strains and currently in clinical use [6,7]. In a program aimed to synthesize biologically active compounds, in detail we are searching for a hybridization of the fluroquinolone with benzimidazole [8][9][10][11]. Herein, the carboxylic acid moiety was coupled with o-phenylenediamine and thereafter cyclized to produce the target compound.…”