Figure 18: Production of peroxynitrite anion radical (ONOO▪-) from NO radical combines with superoxide anion radical (O2▪-). Peroxynitrite anion radical (ONOO▪-) causes nitration and hydroxylation, which cases deformation of protein or nucleic acids and results in sterilization. Nitration and hydroxylation are oxidation reactions. Peroxynitrite anion radical (ONOO▪-) may be the precursor of OH radical if H+ combines to ONOO▪- and degrades to •OH and •NO2.