Sulfonamides, also known as sulfa drugs, are synthetic antimicrobial agents derived from sulfonic acid. In bacteria, these drugs are competitive inhibitors of para-aminobenzoic acid (PABA), a substrate of the enzyme dihydropteroate synthetase. This reaction is necessary in these organisms for the synthesis of folic acid. more...
The first sulfonamide was trade named prontosil. The first experiments with prontosil began in 1932 by the German chemist Gerhard Domagk, and the results were published in 1935 (after his employer, IG Farben, had obtained a patent on the compound). Prontosil was a red azo dye, and in mice had a protective action against streptococci. It had no effect in the test tube, and only exerted an antibacterial effect in the live animal itself. And, with war on the horizon, there was interest among the Allies to break the German patent.
Soon it was discovered (1936) that prontosil's active agent was a smaller, more effective compound known as sulfanilamide:
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