arsenous acid

Arsenous acid (H3AsO3) is an inorganic oxoacid of arsenic in which three hydroxy groups are attached to a central arsenic atom in the +3 oxidation state. It exists only in aqueous solution and cannot be isolated as a pure compound; its anhydride form is arsenic trioxide (As2O3). In water, As2O3 slowly hydrolyzes to form arsenous acid. Arsenous acid and its conjugate bases (arsenite ions) have been historically used in medicine—most notably as the active species in Fowler’s solution for conditions such as malaria and syphilis—but their use has been largely discontinued due to toxicity. The biologically active form of intravenous arsenic trioxide therapy for acute promyelocytic leukemia is believed to be arsenous acid formed upon dissolution. Mechanistically, it acts by inhibiting proliferation and inducing apoptosis or differentiation of malignant cells; one identified molecular target is thioredoxin reductase[5][7][9]. Chronic exposure or misuse can cause severe toxicity including carcinogenicity.

Other names

arsenious acidarsorous acidtrihydroxyarsineH3AsO3H-3AsO3H 3AsO3