EFEITOS DE MICRO-HIDRATAÇÃO EM PROPRIEDADES CONFORMACIONAIS E ESPECTROSCÓPICAS DO ANTIBIÓTICO MARBOFLOXACINO

Marbofloxacin (MRB) is a fluoroquinolone used as a veterinary antibiotic. Some analytical methods of optical absorption are used for their determination in pharmaceutical formulations. Thus, we decided to study the electronic absorption spectrum of MRB in the UV-Vis region. For this, we use the TD-DFT, COSMO methods - based on the solvation continuum model - and micro-hydration. The interactions of MRB in both water and vacuum were simulated using computational modeling techniques. Ab initio quantum calculations were used to optimize the geometry of the isolated molecule and in the optical transition energy calculations. The solute-solvent simulation was performed with the Molecular Dynamics technique in the NpT ensemble using a temperature of 300 K in the Amber computer package. The system balance was monitored by Root Mean Square Deviation. The analyzes of the absorption spectra were carried out using the micro-hydration method. This method involved the use of different numbers, from 2 to 8, of the water molecules of the first solvation layer to calculate transition energies. The transition energies were calculated using the TD-DFT method at the theory level B3LYP / 6-311G using together the Conductor-like Screening Model solvation model that assesses the effect of the solvent implicit in the system. For all micro-hydration systems, energy absorption decreases as the wavelength increases. Observing the values it is noticed that there was a deviation in the absorption spectrum 325.4 nm (in the isolated molecule) to 274.1 (with the addition of water). These values are within the experimental ones where we have the bands with maximum absorption at 268 nm and 335 nm.