Inhibition of Clostridium perfringens by naphthoquinones

ABSTRACT The minimum inhibitory concentrations (MICs) of several naphthoquinones (NQ) were determined in the presence or absence of nitrite (NO2−) against various strains of Clostridium perfringens. In fluid thioglycollate medium, MICs ranged from 70–100 ppm for 2‐methyl‐1,4‐NQ (menadione), 200–280 ppm for 1,4‐NQ, 180–250 ppm for 1,2‐NQ, >500 ppm for several water‐soluble derivatives and 100–300 ppm for NO2−. Using a type B strain in homogenized meat medium, MICs were 670 ppm for menadione, 620 ppm for 1,4‐NQ and 770 ppm for NO2−. Nitrite, menadione and 1,4‐NQ exhibited comparable and additive rather than synergistic inhibition. Some NQ compounds may have potential as partial nitrite substitutes subject to safety evaluation.