1. ANTIBIOTICS Dr.Tawfeq A. Al-Howiriny Associate Professor talhowiriny@yahoo.com

2. β- Lactam Antibiotics - Lactam is an amide, it is a cyclic amide and not open chain amide - Any nitrogen bound to carbonyl group is always neutral - In ammonia, This pair of electron is responsible about the basicity, loss of this pair leads to loss of basicity

3. β - Lactam Antibiotics - β- lactam antibiotics : 1- Penicillins 2- Cephalosporins 3- Carbapenems 4- Monobactams - Penicillins 1- Natural penicillins 2- Biosynthetic penicillins 3- Semisynthetic penicillins

4. β- Lactam Antibiotics Natural penicillins : - Alexander Fleming : P. notatum, Penicillin, S.aureus - In the world war II wounded soldiers S. aureus - In 1939, Florey and chain examined penicillin chemically penicillin “ mixture “ - The mixture has one major component that was called “ British pen “, or, “ Penicillin I “, or “ Penicillin F “ - It was active against S. aureus as well as many other G+ve organisms - It is excreted very fast from the body and the yield from the fungus is low - Therefore, in early 40 ’ s, Penicillin I was restricted for military use only

5. β - Lactam Antibiotics - -They tried to find another fungus that can pnduce the same penicillin in high yield - -They found a similar but not identical to P. notatum, it was P. chrysogenum - -The fungus was cultured in a media containing corn steep liqour - It produced one major component, American pen, penicillin II, or penicillin G