UNITEFA   23945
UNIDAD DE INVESTIGACION Y DESARROLLO EN TECNOLOGIA FARMACEUTICA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
MACROMOLECULAR OXIDATION CAUSED BY CITRIC ACID IN BACTERIUM
Autor/es:
RODRÍGUEZ VARELA MACARENA; ALBESA INÉS; AIASSA VIRGINIA
Lugar:
CÓRDOBA
Reunión:
Congreso; XI Congreso Argentino de Microbiología General; 2015
Institución organizadora:
SAMIGE
Resumen:
Citric acid (CA) is a weak organic acid it is a natural preservative which occurs naturally in citrus fruits and is also used to add anacidic or sour taste to foods and drinks. In biochemistry, the conjugate base of CA, citrate, is important as an intermediate in theCA cycle, which occurs in the metabolism of all aerobic organisms. Commonly is used in the food, cosmetic and pharmaceuticalindustries for its pleasant taste and low toxicity. Also, it has been used for its topical antibacterial effect against Pseudomonasaeruginosa multiresistant. Studies show that a greater concentration of 40 mM significantly reduced populations of Cronobactersakazakii and Salmonella enterica serovar Typhimurium. According to the above, the objective of our study was to evaluate ifthe antimicrobial effect of CA could be due to oxidative damage and consequent macromolecular bacterial oxidation. Theminimum inhibitory concentration (MIC) to CA in Staphylococcus aureus 29213 and Escherichia coli 35218 was determinedusing the standard tube dilution method as outlined by the Clinical Laboratory Standards Institute. As markers of proteinoxidation, advanced oxidation protein products (AOPP) can be determined spectrophotometrically by a colorimetric assay withpotassium iodide and acetic acid, while nitrosylation be evaluated by Saville assay. To determine the degree of lipid oxidation inbacterium cells used malondialdehyde (MDA) with thiobarbituric acid which leads to the formation of a colored product whichabsorbs at 535 nm. In all assays were used CA concentrations of 20 (sub MIC), 40 (MIC) and 80 (supraMIC) mM. S. aureus andE. coli showed an CA MIC of 40 mM. As regards the oxidation of macromolecules, it was observed that in S. aureus theoxidative damage was mediated by protein oxidation and nitrosylation while lipid peroxidation was not observed. In contrast in E.coli, a Gram negative bacterium with more lipid exposure, only lipid peroxidation was observed at the different concentrationsassayed CA. The primary antimicrobial action of CA is its ability to inhibit the growth of many bacteria. The undissociated form ofCA penetrates the cell membrane and enters the cytoplasm where it reduces the intracellular pH and disrupts thetransmembrane proton-motive force. In addition, CA acts as a chelating agent and inhibits the growth of bacteria by chelatingdivalent metal ions. The present investigation about the macromolecular oxidation caused by CA may foster the study of theoxidative injure of proteins and lipids as the other factor involved in the action of CA. The results of this study may contribute to abetter understanding of antimicrobial mechanisms of CA.