Candidacidal activities of the glucose oxidase-mediated lactoperoxidase system

The purpose of this study was to investigate the candidacidal activity of the glucose oxidase-mediated lactoperoxidase system at various levels of glucose and glucose oxidase.

Candida albicans ATCC strains 18804, 10231, 11006, bovine lactoperoxidase (25 and 50 μg/mL), and KSCN (1 mM) were used. Different levels of glucose oxidase (1, 5, 10, and 20 units/mL) and glucose (0.03, 0.3, and 3.0 mg/mL) were added to complete the system. The candidacidal activity of the system was examined by preincubating its components for 0-60 min, and then with C. albicans. Candidacidal activity was determined by comparing the numbers of CFU and calculating the percent loss of cell viability.

The system displayed 13.9-27.4% (without preincubation) to 28.6-34.3% (preincubation for 60 min) loss of viability at 25 μg/mL of bovine lactoperoxidase, 10 units/mL of glucose oxidase, and 0.03 mg/mL of glucose; similar results were obtained with 20 units/mL of glucose oxidase or 0.06 mg/mL of glucose. The candidacidal activity of the system increased markedly as the glucose concentration increased. The candidacidal activity displayed 87.2% (without preincubation) to 100.0% (preincubation for 60 min) at 3.0 mg/mL of glucose. At 3.0 mg/mL of glucose, the system containing 1 or 5 units of glucose oxidase also showed significant levels of candidacidal activity.

The candidacidal activity of the glucose oxidase-mediated lactoperoxidase system at physiological concentrations of salivary glucose was moderate, but was greatly elevated with increases of glucose level.