Penicillin

Penicillin consists of two aromatic groups, two amide groups, one sulfide group, and one carboxylic acid group.
Penicillin antibiotics were among the first medications to be effective against many bacterial infections caused by staphylococci and streptococci.
About 10% of people report that they are allergic to penicillin, but these reactions are usually easily controlled.
Penicillin and other β-lactam antibiotics act by inhibiting penicillin-binding proteins, which normally catalyze cross-linking of bacterial cell walls.
Side effects include diarrhoea, hypersensitivity, nausea, rash, neurotoxicity, urticaria, and superinfection.
Penicillin was discovered in 1928 by Scottish scientist Alexander Fleming. People began using it to treat infections in 1942. Penicillin is still used today.
There are several enhanced penicillin families which are effective against additional bacteria; these include the antistaphylococcal penicillins, aminopenicillins and the antipseudomonal penicillins. They are derived from Penicillium fungi.
Penicillin is FDA approved.

References:

Penicillin: Project