Physiological activity of arsenicals

In general As organic derivatives are more toxic than As derivatives. The use of organoarsenicals in medicine dates from the discovery in 1905 by H. W. Thomas that atoxyl (first made by A. Bechamp in 1863) cured experimental trypanosomiasis (e.g. sleeping sickness). In 1907 P. Erlich and A. Bertheim showed that atoxyl was sodium hydrogen 4-aminophenylarsonate 

Erlich and A. Bertheim showed that atoxyl was sodium hydrogen 4-aminophenylarsonate 

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