PYRITHIONE BIOCIDE INTERACTIONS WITH BACTERIAL PHOSPHOLIPID HEAD GROUPS

Sodium pyrithione and zinc pyrithione (NaPT and ZnPT, respectively) ar e antimicrobial agents widely used in both the cosmetics and fuel indu stries. They are also utilized in the mining industry because of their metal chelating properties. They have been shown to depolarize membra ne electropotential in fungi and are also known to inhibit fungal and bacterial substrate transport processes. Recent work has shown that bo th pyrithiones cause the leakage of intracellular material (potassium ions and O.D.(260nm) absorbing material) from exposed bacterial cells. The work here reports studies on the interactions between the pyrithi ones and the bacterial phospholipid head group structures, at both a p ractical and a theoretical level, utilizing tube dilution neutralizer studies, scanning spectrophotometry and molecular modelling. The tube dilution neutralizer studies exhibited a decrease in minimum inhibitor y concentration (MIC) for both pyrithiones in the presence of extracel lular phosphatidylethanolamine and EDTA. Scanning spectrophotometry ex hibited the chelation of the central zinc atom from the ZnPT chelate b y the addition of EDTA. Molecular modelling studies exhibited the chel ation of the phosphatidyl-ethanolamine head group by ZnPT. Zinc pyrith ione also exhibited an interaction with the ammonium tail of the head group structures. Sodium pyrithione exhibited electrostatic interactio ns with the phospholipid head groups in the molecular modelling studie s.