Arsphenamine

Arsphenamine, also known as Salvarsan or compound 606, is a drug that was introduced at the beginning of the 1910s as the first effective treatment for syphilis, and was also used to treat trypanosomiasis. This organoarsenic compound was the first modern chemotherapeutic agent.Arsphenamine was first synthesized in 1907 in Paul Ehrlich's lab by Alfred Bertheim. The antisyphilitic activity of this compound was discovered by Sahachiro Hata in 1909, during a survey of hundreds of newly synthesized organic arsenical compounds. Ehrlich had theorized that by screening many compounds, a drug could be discovered that would have anti-microbial activity but not kill the human patient. Ehrlich's team began their search for such a 'magic bullet' among chemical derivatives of the dangerously toxic drug atoxyl. This project was the first organized team effort to optimize the biological activity of a lead compound through systematic chemical modifications, the basis for nearly all modern pharmaceutical research.Salvarsan has long been assumed to have an As=As double bond, akin to the N=N linkage in azobenzene. However, in 2005, in an extensive mass spectrometric analysis Salvarsan was shown to have As–As single bonds, not As=As double bonds. The drug was also found to be a mixture consisting of cyclo-As3 and cyclo-As5 species.