Effects of safrole on the defensive functions of human neutrophils

The effects of safrole on the defensive functions of human neutrophils were examined. At the concentrations employed in this study, safrole did not significantly affect the viability of peripheral blood neutrophils as verified by their ability to exclude trypan blue dye. However, exposure of neutrophils to safrole inhibited their bactericidal activity against oral pathogens, including Actinobacillus actinomycetemcomitans and Streptococcus mutans, in a dose dependent manner. In addition, safrole inhibited the production of bactericidal superoxide anion by neutrophils as measured by cytochrome c reduction. In conclusion, the results demonstrated that safrole reduced the antibacterial activity and the superoxide anion production of neutrophils. Inhibition of the defensive functions of neutrophils may be one possible mechanism by which safrole compromises the oral health.