Antibacterial activity of triarylmethanes derivatives on Staphylococcus aureus

PAEZ, PAULINA LAURA; AIASSA MARTINEZ, IVANA; ALBESA, INÉS; BECERRA, MARÍA CECILIA; ARGÜELLO GA

Córdoba

Congreso; 1º Reunion Internacional de Ciencias Farmaceuticas.; 2010

Introduction Photodynamic therapy (PDT) is based on the concept that certain photosensitizers (PS) can be localized in neoplasic tissue and subsequently these photosensitizers can be activated with the appropriate wavelength of light to generate active molecular species that produce toxicity to cell and tissues (1,2). Antimicrobial PDT research has increased in the last 20 years because of concerns resulting from the emergence of antibiotic-resistant bacterial strains. Control 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 unlike to induce resistance in microorganisms (3). Materials and methods Staphylococcus aureus ATCC 29213 was grown aerobically in trypticase soy broth. The antimicrobial activity of the compounds was evaluated by using the standard tube dilution method on Mueller Hinton Broth. Bacterial growth was observed at 18 h of incubation, following the indications of the Clinical and Laboratory Standards Institute. A macrodilution method was used to determine the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC). Bacterial suspension incubated with New Fuchsin (NF) were irradiated at 0, 1, 6, 18 and 24 h and incubated for 18 h to 37 ¨¬C. Reactive oxygen species (ROS) were investigated by reduction of Nitro blue Tetrazolium. The antimicrobial activity of the compounds was evaluated by using the standard tube dilution method on Mueller Hinton Broth. Bacterial growth was observed at 18 h of incubation, following the indications of the Clinical and Laboratory Standards Institute. A macrodilution method was used to determine the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC). Bacterial suspension incubated with New Fuchsin (NF) were irradiated at 0, 1, 6, 18 and 24 h and incubated for 18 h to 37 ¨¬C. Reactive oxygen species (ROS) were investigated by reduction of Nitro blue Tetrazolium. ATCC 29213 was grown aerobically in trypticase soy broth. The antimicrobial activity of the compounds was evaluated by using the standard tube dilution method on Mueller Hinton Broth. Bacterial growth was observed at 18 h of incubation, following the indications of the Clinical and Laboratory Standards Institute. A macrodilution method was used to determine the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC). Bacterial suspension incubated with New Fuchsin (NF) were irradiated at 0, 1, 6, 18 and 24 h and incubated for 18 h to 37 ¨¬C. Reactive oxygen species (ROS) were investigated by reduction of Nitro blue Tetrazolium. Results S. aureus was found to be susceptible to NF with a MIC and MBC of 1 ¥ìg/mL. Malachite green (MG) showed the highest activity with a MIC of 0.002¥ìg/mL and a MBC of 0.063¥ìg/mL while CV showed MIC of 0.098¥ìg/mL and a MBC of 0.39¥ìg/mL. When S. aureus cultures (106 CFU/mL), not exposed to NF, were illuminated for 24 h, did not decrease the number of viable cells. In the presence of NF and light treatment the reduction percentages of survivors after 1, 6, 18 and 24 h were 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 been improved the performance of the PS against the above 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 obtained results for ROS generation at all concentrations and times assayed showed similar values than the controls. The obtained results for ROS generation at all concentrations and times assayed showed similar values than the controls. 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 obtained results for ROS generation at all concentrations and times assayed showed similar values than the controls. The obtained results for ROS generation at all concentrations and times assayed showed similar values than the controls. When S. aureus cultures (106 CFU/mL), not exposed to NF, were illuminated for 24 h, did not decrease the number of viable cells. In the presence of NF and light treatment the reduction percentages of survivors after 1, 6, 18 and 24 h were 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 been improved the performance of the PS against the above 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 obtained results for ROS generation at all concentrations and times assayed showed similar values than the controls. The obtained results for ROS generation at all concentrations and times assayed showed similar values than the controls. 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 obtained results for ROS generation at all concentrations and times assayed showed similar values than the controls. The obtained results for ROS generation at all concentrations and times assayed showed similar values than the controls. was found to be susceptible to NF with a MIC and MBC of 1 ¥ìg/mL. Malachite green (MG) showed the highest activity with a MIC of 0.002¥ìg/mL and a MBC of 0.063¥ìg/mL while CV showed MIC of 0.098¥ìg/mL and a MBC of 0.39¥ìg/mL. When S. aureus cultures (106 CFU/mL), not exposed to NF, were illuminated for 24 h, did not decrease the number of viable cells. In the presence of NF and light treatment the reduction percentages of survivors after 1, 6, 18 and 24 h were 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 been improved the performance of the PS against the above 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 obtained results for ROS generation at all concentrations and times assayed showed similar values than the controls. The obtained results for ROS generation at all concentrations and times assayed showed similar values than the controls. 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 obtained results for ROS generation at all concentrations and times assayed showed similar values than the controls. The obtained results for ROS generation at all concentrations and times assayed showed similar values than the controls. S. aureus cultures (106 CFU/mL), not exposed to NF, were illuminated for 24 h, did not decrease the number of viable cells. In the presence of NF and light treatment the reduction percentages of survivors after 1, 6, 18 and 24 h were 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 been improved the performance of the PS against the above 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 obtained results for ROS generation at all concentrations and times assayed showed similar values than the controls. The obtained results for ROS generation at all concentrations and times assayed showed similar values than the controls. 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 obtained results for ROS generation at all concentrations and times assayed showed similar values than the controls. Conclusions The photodynamic therapy with the use of NF may be an effective bactericidal method against S. aureus and potentially against other bacterial pathogens. The ROS are not involved in the mechanism of bacterial killing. We conclude that the most important specie involved in the mechanism of bacterial killing is the TAM radical from the TAM triplet principally.S. aureus and potentially against other bacterial pathogens. The ROS are not involved in the mechanism of bacterial killing. We conclude that the most important specie involved in the mechanism of bacterial killing is the TAM radical from the TAM triplet principally.