STUDIES ON THE STRUCTURE OF FQS SPECIES PRESENT AT DIFFERENT pH´s AND THEIR INTERACTIONS WITH LYSOZYME PROTEIN

HUGO A. PÉREZ; LEDESMA, ANA ESTELA; FRIAS, MARIA ANGELES

Ciudad Autónoma de Buenos Aires

Encuentro; XLVI Reunión Anual de la Sociedad Argentina de Biofísica; 2017

Fluoroquinolones (FQs) are synthetic antimicrobial agents with a broad spectrum of antibiotic activity against Gram-positive and Gram-negative bacteria. They play an important role in the treatment and prevention of disease in both humans and animals. On the other hand, patients often take antibiotics with foods or dairy products such as milk to help swallow easier and to decrease their gastrointestinal side effects. Therefore FQs may be in contact with proteins present in milk as lysozyme (Lyz). It is known, that food?drug interactions may occur by many mechanisms, and they can result in changes both in the rate and the extent of absorption. The pH of the gastric milieu may also be an important determinant of the magnitude of the interaction. In this context the purpose of this work is to study the structure of Ciprofloxacin (Cpx) and Levofloxacin (Lev) species present at basic, acid and neutral pH´s and their interactions with Lyz structure by Fourier transform infrared spectroscopy (FTIR) and Theoretical Calculations. Theoretical calculations using DFT/B3LYP/Lanld2z methodology with gaussian09 program calculate that the more stable structure in solution is the neutral ones for both FQs. Docking Molecular analysis predict that the main forces involved in the interaction between FQs species and Lyz protein are Van der Waals forces and hydrogen bond. These results are in agreement with FTIR in solid phase and buffered solution. The spectra show significant changes in the quinolone carboxylic group and the piperazine amine group. When Lyz is present, it is observed that the FQs modify the secondary structure of Lyz. These theoretical and spectroscopic studies give a deeper understanding of the structural changes occurring between Cpx and Lev molecules with Lyz protein.