Antibacterial Activity of Triarylmethane Derivatives on Staphylococcus aureus.

PL PÁEZ; IM AIASSA MARTÍNEZ; I ALBESA; MC BECERRA; GA ARGÜELLO

Ciudad de Córdoba. Argentina.

Congreso; 1st International Meeting on Pharmaceutical Sciences (1º RICiFa).; 2010

Departamento de Farmacia - Facultad de Ciencias Químicas - Universidad Nacional de Córdoba

Photodynamic therapy (PDT) is based on the concept that certain photosensitizers (PS) can be localized in neoplasic tissue and subsequently be activated with the appropriate wavelength of light to generate active molecular species that produce toxicity in cells and tissues. Antimicrobial PDT research has increased in the last 20 years. The control of infections by chemotherapic agents is often jeopardized by the spreading of bacterial strains resistant to many conventional antibiotics. As PDT is a multi-target process, it is unlikely to induce resistance in microorganisms. Staphylococcus aureus was found to be susceptible to NF+ with a MIC and MBC of 1 µg/mL. Malachite green (MG+) showed the highest activity with a MIC of 0.002µg/mL and a MBC of 0.063µg/mL while Crystal Violet (CV+) showed a MIC of 0.098µg/mL and a MBC of 0.39µg/mL. When S. aureus cultures without NF, were illuminated for 24 h, they did not decrease the number of viable cells. In the presence of NF and light treatment, the percentages of survivors after 1, 6, 18 and 24 h were reduced by 1.4 %, 1.5%, 93.2% and 93.9%, respectively. Thus, increasing the time of the contact between the PS and the bacterial cells has improved the performance of the PS against the mentioned bacteria. An efficient photoinactivation of S. aureus was obtained from a light exposure time of 6 h. shorter irradiation times did not further affect the percentage of photoinactivated bacteria. The results obtained for ROS generation at all concentrations and times assayed showed similar values to the controls.