Beta Lactam Antibiotics

by Adam Le Gresley, PhD

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    Now, we come onto to the final lecture in Module 4. And this relates to beta-lactam antibiotics. Hopefully, you’ll be able to appreciate, having gone through a number of functional groups, some of the structural changes that we make to these antibiotics in order to improve their spectrum of activity, their resistance to beta-lactamases and also, as we will see, their oral bio-availability. As you’ll probably be aware, antibiotics are one of the most-frequently prescribed medications. They achieve this by selective toxicity to the pathogen which is a key concept in antibiotic therapy. And approximately, half of the world’s sales of antibiotics are due to the beta-lactam class of antibiotic, which we’ll be discussing today. They all work in pretty much the same way, that is to say, they disrupt bacterial cell wall synthesis. And they are good examples of enzyme inhibitors that are irreversible. Bacterial cell walls offer a selective target for therapy in the case of bacteria because normal healthy eukaryotic cells, of course, do not have cell walls, consisting of a cell membrane alone. So, let’s touch upon penicillins. Before I go into the full structure of penicillins, I’d like you to pay attention to the sub-structure I’ve shown on the right hand side. This, you should recognise from Module III, is an amide. Note, we have a carbonyl-carbon to which is attached a nitrogen. But, it is a particular type of amide. It is cyclic. And cyclic amides are known as lactams. And it is this beta-lactam, because we have an alpha and a beta carbon separating the carbonyl and the nitrogen components, that are the core component of penicillins. I’ve shown here, at the bottom right hand side, the general structure for penicillins. And these penicillin class were first discovered in 1929 by Fleming, consisting...

    About the Lecture

    The lecture Beta Lactam Antibiotics by Adam Le Gresley, PhD is from the course Medical Chemistry. It contains the following chapters:

    • Beta lactam antibiotics
    • Peptidoglycan
    • Action of transamidase
    • Problems with penecillins
    • The problem of beta lactamases
    • Other approaches to beta lactamase issue
    • Carbapenams

    Included Quiz Questions

    1. Improved spectrum of activity
    2. Reduced aqueous solubility
    3. Greater resistance to bacterial β-Lactamases
    4. Reduced risk of intramolecular β-Lactam hydrolysis
    5. None of the above

    Author of lecture Beta Lactam Antibiotics

     Adam Le Gresley, PhD

    Adam Le Gresley, PhD

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