arsenite

Arsenite refers to the class of inorganic compounds containing **arsenic in the +3 oxidation state**, classically represented as arsenic oxyanions such as AsO₂⁻ or AsO₃³⁻[9]. These compounds are highly **toxic** and occur naturally, as well as synthetically, and are encountered in both environmental contamination (e.g., groundwater) and occupational settings[8][4]. Arsenite ions disrupt biological processes by binding with sulfhydryl groups on cysteine residues of proteins and enzymes, inhibiting their activity—particularly in energy metabolism and cellular signaling[2][4]. This mechanism underlies the toxicity and carcinogenicity of arsenite. Arsenite compounds (and related salts, e.g., potassium arsenite) have been used historically as pesticides and therapeutic agents, but their medical use is now obsolete due to severe toxicity[3]. Arsenite is slightly more toxic than arsenate (+5 form), but both pose substantial health risks; they are easily interconverted in biological and environmental systems[4]. No major pharmaceutical brands currently use arsenite as an active drug.

Other names

arsenic(III)arsenic trioxide (when hydrated or in common pharmaceutical form)arsenous acid (when protonated)AsO₂⁻ (main oxyanion form)AsO₃³⁻ (another oxyanion form)arsenic oxyanion (+3 state)