A NOVEL ASSAY FOR THE DISTRIBUTION OF PYRITHIONE BIOCIDES IN BACTERIAL-CELLS

Sodium pyrithione and zinc pyrithione (NaPT and ZnPT, respectively) ar e widely used as cosmetic preservatives and metal chelating agents, Th ey are commonly assayed using thin layer chromatography (TLC) and high performance liquid chromatography (HPLC), However, a simple quantitat ive colorimetric assay has not been previously reported for these comp ounds, This paper describes the development of a spectrophotometric as say for the quantification of the pyrithiones which is based on the ch elation of copper (II) ions by the biocides, This assay was developed in order to facilitate the determination of the distribution of these biocides in the Gram-negative bacteria Escherichia coli NCIMB 10000 an d Pseudomonas aeruginosa NCIMB 10548. Sodium pyrithione was exhibited only in the cytosol of E, coli and Ps, aeruginosa. Zinc pyrithione, ho w-ever, was assayed in the cytosol of both bacteria and was found in t he cell envelope of Ps, aeruginosa. These findings suggest that the py rithione biocides are active within bacterial cells as well as at the cell membrane.