Hydrogen peroxide produced by oral commensal streptococci can react with nitrite to form other reactive nitrogen species such as:

Hydrogen peroxide produced by oral commensal streptococci can react with nitrite to form other reactive nitrogen species such as:

• A. Hypochlorous acid
• B. Nitrous oxide
• C. Peroxynitrite
• D. Ozone

Answer: (C)

Nitrogen-centered reactive species are produced when nitric oxide and superoxide combine to form peroxynitrite. In the oral environment, nitrite can be reduced by bacteria to nitric oxide, providing NO, while hydrogen peroxide from commensal streptococci helps generate reactive oxygen species such as superoxide. The rapid reaction between NO and superoxide yields peroxynitrite (ONOO−), a potent reactive nitrogen species that can modify biomolecules. Among the options, peroxynitrite fits this nitrite–H2O2–ROS interaction best. The other choices involve species formed through different pathways (hypochlorous acid relies on chloride and MPO, nitrous oxide is a different N-oxide, and ozone is not produced by this microbial interaction).

Nitrogen-centered reactive species are produced when nitric oxide and superoxide combine to form peroxynitrite. In the oral environment, nitrite can be reduced by bacteria to nitric oxide, providing NO, while hydrogen peroxide from commensal streptococci helps generate reactive oxygen species such as superoxide. The rapid reaction between NO and superoxide yields peroxynitrite (ONOO−), a potent reactive nitrogen species that can modify biomolecules. Among the options, peroxynitrite fits this nitrite–H2O2–ROS interaction best. The other choices involve species formed through different pathways (hypochlorous acid relies on chloride and MPO, nitrous oxide is a different N-oxide, and ozone is not produced by this microbial interaction).