PHOTODYNAMIC INACTIVATION OF GRAM POSITIVE AND GRAM NEGATIVE BACTERIAS BY THE AMINOPORPHYRIN A4 AND A4+

GHIO LARA CAROLINA; MORA, JIMENA; ALVAREZ MARÍA GABRIELA; DURANTINI EDUARDO; LOMBARDO, MARÍA ELISA; MARÍA DEL CARMEN MARTINEZ

Mar del Plata

Congreso; LXIV Reunión Anual de la Sociedad Argentina de Investigación Clínica; 2019

SAIC

Photodynamic inactivation (PDI) is an alternative therapy to antibiotics treatment against for localized infections, particularly those caused by conventional antimicrobial agents resistant organisms. PDI is based on a preferential accumulation of a photosensitizer (PS) by microbial cells; illumination induces photodynamic activity producing lethal damage in the cells. Porphyrins, due to their molecular structure, are used as PS in PDI. In this study the effect of the synthetic porphyrin 5,10,15,20-tetrakis [4-(3-N, Dimethylaminopropoxy)phenyl] porphyrin (A4) and its protonated form (A4+) as PS to inactivate S. aureus and E. coli were studied. Microbial viability was determined by CFU/ml Petri dish counting.As light source, fluorescent tubes placed 20 cm from the sample (0.5 mW/cm2) were use. Microorganisms were incubated with PSs and exposed 15 minin darkness and 15 minin light or 30 min in darkness. Inhibitory concentration 50 (IC50) values PS uptake by bacterias and oxidative damage were evaluated.To calculate Selectivity index, cytotoxicity in Vero cells was studied. Porphyrins showed low cytotoxicity in mammal cells. IC50 values for to S. aureus in light condition were 2.4±0.6 μM for A4 and 6.0± 0.7 μM for A4+.No inhibition was shown by E. coli with the concentrations studied. High uptakes levels of A4 and A4+ were observed independently of the illumination, around 2.0 umol/ml of inoculum for S. aureus; while in E. coli the A4+ uptake was 3 times greater than for A4. PS uptake correlated with an increase in the cells internal oxidative status. Porphyrins plus light treatment increased 500% the lipid peroxidation levels in S. aureus compared to controls, while in E coli TBARS levels were 300% for A4 and 500% for A4+. Both porphyrins were more effective against S. aureus than for E. coli, but A4+ showed a remarkable toxic effect in E. coli without reaching high mortality. In conclusion A4 and A4+ could be used for PDI against Gram positive bacteria.