Dispersive liquid-liquid microextraction of quinolones in porcine blood: Validation of a CE method using univariate calibration or multivariate curve resolution-alternating least squares for overlapped peaks.

In the previously published part of this study, we detailed a novel strategy based on dispersive liquid-liquid microextraction to extract and preconcentrate nine fluoroquinolones in porcine blood. Moreover, we presented the optimized experimental conditions to obtain complete CE separation between target analytes. Consequently, this second part reports the validation of the developed method to determine flumenique, difloxacin, enrofloxacin, marbofloxacin, ofloxacin, ciprofloxacin, through univariate calibration, and enoxacin, danofloxacin, and gatifloxacin through multivariate curve resolution analysis. The validation was performed according to FDA guidelines for bioanalytical assay procedures and the European Directive 2002/657 to demonstrate that the results are reliable. The method was applied for the determination of fluoroquinolones in real samples. Results indicated a high selectivity and excellent precision characteristics, with RSD less than 11.9% in the concentrations, in intra- and interassay precision studies. Linearity was proved for a range from 4.00 to 30.00 mg/L and the recovery has been investigated at four different fortification levels, from 89 to 113%. Several approaches found in the literature were used to determinate the LODs and LOQs. Though all strategies used were appropriate, we obtained different values when using different methods. Estimating the S/N ratio with the mean noise level in the migration time of each fluoroquinolones turned out as the best studied method for evaluating the LODs and LOQs, and the values were in a range of 1.55 to 4.55 mg/L and 5.17 to 9.62 mg/L, respectively.

Tuberculosis: finding a new potential antimycobacterium derivative in a aldehyde-arylhydrazone-oxoquinoline series.

Tuberculosis (TB) is a contagious disease caused by Mycobacterium tuberculosis, which remains a serious public health problem. The emergence of resistant bacterial strains has continuously increased and new treatment options are currently in need. In this work, we identified a new potential aldehyde-arylhydrazone-oxoquinoline derivative (4e) with interesting chemical structural features that may be important for designing new anti-TB agents. This 1-ethyl-N'-[(1E)-(5-nitro-2-furyl)methylene]-4-oxo-1,4-dihydroquinoline-3-carbohydrazide (4e) presented an in vitro active profile against M. tuberculosis H37Rv strain (minimum inhibitory concentration, MIC = 6.25 µg/mL) better than other acylhydrazones described in the literature (MIC = 12.5 µg/mL) and close to other antitubercular agents currently on the market. The theoretical analysis showed the importance of several structural features that together with the 5-nitro-2-furyl group generated this active compound (4e). This new compound and the analysis of its molecular properties may be useful for designing new and more efficient antibacterial drugs.

Actividad in vitro de CQ-EPCA-297-S en comparación con quinolonas y cefalosporinas de tercera generación de 212 bacterias patógenicas aisladas de enfermos de la ciudad de Querétaro / Comparison of the in vitro activity of CQ-EPCA-297-S, with quinolones and third generation cephalosporins against 212 clinical isolates from patients from Querétaro, Mexico

En este estudio se presenta la susceptibilidad in vitro de un nuevo antimicrobiano denominado cefaquinolona (CQ-EPCA-297-S), desarrollado por Laboratorios Aranda mediante la hibridación de un grupo fluoroquinolínico con un derivado del ácido 7-aminocefalosporánico, en 212 bacterias grampositivas y gramnegativas y comparado contra tres cefalosporinas de tercera generación y dos fluoroquinolonas de mayor uso terapéutico. Utilizando el método de difusión en agar (Kirby-Bauer) se observó 100 por ciento de sensibilidad contra bacterias grampositivas y 97.3 por ciento contra gramnegativas. Se concluye que la actividad in vitro de CQ-EPCA fue superior a los otros antimicrobianos evaluados, existiendo la posibilidad de uso terapéutico en el futuro.