Effects of areca nut extracts on the functions of human neutrophils in vitro

Aqueous extracts of ripe areca nut without husk (ripe ANE) and fresh and te nder areca nut with husk (tender ANE) were examined for their effects on th e defensive functions of human neutrophils. Exposure of peripheral blood ne utrophils to ripe ANE and tender ANE inhibited their bactericidal activity against oral pathogens, including Actinobacillus actinomycetemcomitans and Streptococcus mutans, in a dose-dependent manner. At the concentrations tes ted, ripe and tender ANEs did not significantly affect the viability of neu trophils as verified by their ability to exclude trypan blue dye. However, both ANEs inhibited the production of bactericidal superoxide anion by neut rophils as measured by cytochrome c reduction. Moreover, the ripe ANE inhib ited neutrophils more effectively than did tender ANE. Arecoline, a major a lkaloid of areca nut, only exhibited an inhibitory effect on the functions of neutrophils when high concentrations were used. Therefore, arecoline cou ld not be used to explain the inhibitory effects observed for ANEs. In conc lusion, our results demonstrated that ripe and tender ANEs reduced the anti bacterial activity and the superoxide anion production of neutrophils. This effect may contribute to a less efficient elimination of bacteria from the periodontal environment. Inhibition of the antimicrobial functions of neut rophils may alter the microbial ecology of the oral cavity, and this may be one possible mechanism by which areca nut compromises the oral health of u sers of areca nut products.