The potentiation of action of antimicrobial preservatives/antiseptics by, respectively, antioxidants and metal ions has been established. In this investigation the antimicrobial effect of two antioxidants (Butylated hydroxyanisole and Propyl Gallate) and zinc ions, both separately and combined, was determined against three organisms at 37 degrees C. With the exception of Escherichia coli at low zinc concentrations, definite potentiation occurred, as reflected by a decrease in killing times.

The effects of copper and zinc ions on the rate of killing of Gram-negative bacterium Pseudomonas aeruginosa, Gram-positive bacterium Staphylococcus aureus and fungal yeast Candida albicans by antiseptic agents cetylpyridinium chloride and povidone-iodine (Betadine) were investigated. In the 48 test cases copper and zinc ions clearly potentiated the antiseptic agents in 28 (58.3%) cases and exhibited an improved (not clear potentiation) activity in 15 (31.3%) cases. In five (10.4%) cases there was no change in the antiseptics' antimicrobial activity. In general zinc potentiated the antiseptic agents more than copper. If an 'improved activity' was the only criterion for this study, then a more rapid antimicrobial effect was observed in 43 out of the 48 test cases, i.e., 90%.