Reactivators

A reactivator is a compound or agent that restores activity to a system that has been temporarily or permanently deactivated. The term is used across several fields, including biochemistry, pharmacology, and industrial catalysis. In biochemical contexts, reactivators are most often discussed in relation to enzymes that have been inhibited by toxic compounds.

In acetylcholinesterase chemistry, organophosphate nerve agents and certain insecticides disable the enzyme by phosphorylating its active-site serine, blocking neurotransmitter breakdown. Reactivators, typically oximes such as pralidoxime (2-PAM), bind to the phosphorylated enzyme and facilitate the removal of the phosphate group, thereby restoring catalytic activity. The effectiveness of reactivators depends on the specific inhibitor, the aging state of the enzyme, and timing. Some agents can cross the blood–brain barrier to address central nervous system inhibition; others act peripherally.

In industrial catalysis, reactivators or regenerants describe substances used to restore a catalyst's activity after deactivation by poisons, sintering, or fouling. Regeneration strategies may involve chemical washing, oxidative or reductive treatments, or ligand exchange, depending on the catalyst system and poisons involved. Although the term reactivator is used less formally in this context, the underlying goal is the same: recover the functional state of a catalyst without replacing it.

Safety and regulatory considerations are important for reactivators used in medicine and industry. In medical use, reactivators are administered under professional supervision and may be effective only if administered before irreversible aging of the inhibited enzyme occurs.

See also: acetylcholinesterase, organophosphate poisoning, oxime, antidote, catalyst regeneration.