Table 2.
Reactive chemical species. During regular cellular activity living cells generate numerous reactive chemical species containing oxygen, nitrogen, sulfur, carbonyl, halogen, or selenium. Reactive sulfur species can contain thiols or nitrothiols. Free radicals possess at least one unpaired electron that makes highly reactive and short-lived. Nonradicals are oxidizing chemicals or easily converted to free radicals. Superoxide, reactive sulfur species, or reactive selenium species can be reducing agents as reactive nucleophilic species.
| Reactive Chemical Species | |
|---|---|
| Reactive Oxygen Species (ROS) | Free Radicals |
| Superoxide anion (O2−•), Hydroxyl radical (OH•), Alkoxyl radical (RO•), Peroxyl radical (ROO•) | |
| Nonradicals | |
| Hydrogen peroxide (H2O2), Organic hydroperoxide (ROOH), Organic peroxide (ROOR), Singlet oxygen (O21Δg), Ozone (O3) | |
| Reactive Nitrogen Species (RNS) | Free Radicals |
| Nitric oxide radical (NO•), Nitrogen dioxide radical (NO2•) | |
| Nonradicals | |
| Nitrite (NO2−), Nitrate (NO3−), Nitroxyl anion (NO−), Nitrosyl cation (NO+), Peroxynitrite (ONOO−), Peroxynitrate (O2NOO−), Nitrosoperoxycarbonate (ONOOCO2−), Dinitrogen trioxide (N2O3), Dinitrogen tetraoxide (N2O4), Nitryl chloride (NClO2) | |
| Reactive Sulfur Species (RSN) | Free Radicals |
| Thiyl radical (RS•), Peroxysulphenyl radical (RSOO•) | |
| Nonradicals | |
| Hydrogen sulfide (H2S), Thiolate anion (RS−), Thiol (RSH), Hydropersulfide (RSSH), Disulfide (RSSR), Hydropolysulfide (RSSnH), Dialkyl polysulfide (RSSnR), Polysulfide (H2Sx), Sulfenate (RSO−), Sulfinate (RSO2−), Sulfonate (RSO3−), Thiosulmonate (S2O32−), Sulfite (RS2O32−), Sulfate (SO42 −), Thiosulfinate (C6H10OS2), S-nitrosothiols (RSNOs), Nitrosopersulfide (SSNO−), Dinitrosylated sulfite adduct (SULFI/NO) | |
| Reactive Carbonyl Species (RCS) | Nonradicals |
| Acetaldehyde (CH3CHO), Acrolein (Proponel+: C3H4O), Methylglyoxal 4-Hydroxy-nonenal (C9H16O2), 3-Deoxyglucosone (C6H10O5), Glyoxal (C2H2O2), Methylgyoxal (C3H4O2), Electronically excited triplet carbonyls (3L=O*) | |
| Reactive Halogen Species (RHS) | Free Radicals |
| Atomic chlorine (Cl•), Atomic bromine (Br•) | |
| Nonradicals | |
| Hypochlorite (OCl−), Chloramines (RNHCl), Hypobromite (OBr−), Hypoiodite (IO−), Hypohalogenite (XO−; X = F, Cl, Br, or I) | |
| Reactive Selenium Species (RSeS) | Nonradicals |
| Selenite (O3Se−2), Selenate (SeO42−), Selenocysteine (C3H7NO2Se), Selenomethionine (C5H11NO2Se) | |
| Reactive Nucleophilic Species | Free Radicals |
| Superoxide anion (O2−•) | |
| Nonradicals | |
| Hydrogen sulfide (H2S), Thiolate (RS−), Hydropersulfide (RSS−), Disulfide (RSSR), Selenite (O3Se−2), Selenate (SeO42−), Selenocysteine (C3H7NO2Se), Selenomethionine (C5H11NO2Se) | |