| Common reductants are the active metals, hydrogen, hydrogen sulfide, carbon, carbon monoxide, and sulfurous acid. |
| Carbohydrates not only provide the acceptor of sulphide for cysteine biosynthesis, they are the source of reductants for sulphate reduction in non-photosynthetic tissues. |
| Other species can serve as sources of hydrogen or electrons and likewise participate in redox reactions as reductants. |
| Some substances are capable of acting either as reductants or as oxidants, e.g., hydrogen peroxide and nitrous acid. |
| The simultaneous presence of strong oxidants and strong reductants during oxygenic photosynthesis is the basis for regulation. |
| Thiols groups in proteins as endogenous reductants to determine glutathione-protein mixed disulphides in biological systems. |
