Pharmaceutical and medicinal chemistry Flashcards
What is chemotherapy?
It is the use of drugs to selectively kill infectious cells or invading organisms whithout causing injury to the host.
Examples of organic arsenicals
Suramin and Trypasamide
What is penicillin isolated from ?
Penicillium notatum
Examples of beta lactam antibiotics include?
Penicillins
Cephalosporins
Difference between a bacterial and animal cell
-A bacteria cell has a cell wall and a membrane while an animal cell only has a membrane
- An animal has a nucleus while a bacteria cell has no nucleus
What are the mechanism of antibacterial activity
1) inhibition of antemetabolites
egsulphonamide, they inhibit the enzyme catalysed reactions
2)inhibition of cell wall synthesis-eg penicillin and cephalosporins, this leads to bursting or the cell and death
3)inhibition of protein synthesis eg aminogycosides ,tetracyclines
Disruption of protein synthesis eg aminoglycosides and tetracycline, the essential enzymes for cell growth can no longer be synthesized
Inhibition of nucleic acid, replication and transcription-eg quinolones , they stop cell division
What is the Moa of sulphonamide
They act as competitive enzyme inhibitors and block the biosynthesis of folic acid in bacterial cell.
Sulphonamide has a similar structure to paba which allows it to mimic and bind to dihydrofolate preventing it from producing folic acid.
What is the common side effect of sulphonamide
Steven Johnson syndrome
Eg of sulphonamide
Sufadiazine-it’s zinc and silver salts are used to treat burns and wounds
Quinolones
-used as antimalarial agents
-they inhibit synthesis of bacterial dna by interfering with the action of dna gyrase and topoisomerase 2 or 4
What are antibiotics
They are anti infective chemical substances derived from natural sources to kill or stop the activity of bacteria in the host cell
Classification of antibiotics
Can be classified based on
Biogenetic precursors eg amino acid,sugar polypeptide
Moa eg inhibition of cell wall synthesis, protein,nucleic acid,injury to plasma membrane and essential metabolites synthesis inhibitors
Chemical basis eg beta lactam antibiotics,non lactam,unclassified
Examples of beta lactam antibiotics
Penicillins
Cephalosporins
Clavunalic acids
Monobactam
Carbapenams
Penam
Examples of non lactam
Tetracyclines
Aminoglycosides
Polypeptides
Macrolides
Polyene
Examples of non classified
Chloramphenicol
Fusidic acid
Novobiocin
Beta lactam ring contains how many cyclic amides
4 membered cyclic amide
Alpha lactam
3 rings
Gamma lactam
5 rings
Structure of penicillin
It contain a highly strained 4-membered β -lactam ring fused to a 5-membered thiazolidine ring
Characteristics of penicillin’s
They are not lipid soluble so do not crossthe blood Brain barrier
They are excreted and unchanged by the kidneys
solubility and other physical properties are affected by the acyl side chains
How many chiral centers are in penicillin
3
Cephalosporins
Four-membered ring (3-lactam ring) fused
to a six-membered dihydrothiazine ring
Cephalosporins are considered broad
spectrum antibiotic with high potency against gram negative organism
Clavulanic acid
Clavulanic acid is a β-lactam antibiotic produced by Streptomyces clavuligerus.
It is the first clinically used inhibitor