Klarer, Josef

Chrysoidine, which was a deep-red dye, had to be grafted to a sulfonylurea derivative (sulfamidochrysoidine) in order to be active. In 1932, it was studied by two chemists, Fritz Mietzsch and Josef Klarer. Testing the new dye on laboratory rats and rabbits infected with streptococci bacteria, Domagk found that it was highly antibacterial but not toxic. It was called Streptozan , but its name soon changed to Prontosil . 

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