Abstract: The various embodiments of the present invention are directed to pentavalent antimonials, purified pentavalent antimonials, and pentavalent antimonials that are comprised of an antimonial portion and an organic moeity portion. Alternatively the present invention is directed to agents and methods of screening agents which mimic the activity of pentavalent antimonials, particularly sodium stibogluconate and glucatime. An appropriate organic moeity may be selected based upon a desired interaction (e.g. steric action) with active site of a cellular component (e.g. a PTPase). In a preferred embodiment of the present invention the active site includes a cysteine residue which may be impacted by the compositions of the present invention.