D2 Aspirin and Penicillin Flashcards
who was penicillin discovered by and how
alexander fleming, noticed that a fungus that contaminated some of his cultures generated a clear region w/o bacterial growth
structure of penicillin
dipeptide formed from two amino acids: cysteine + valine.
molecule consists of a Sulfur atom,
attached to a four-membered ring containing a cyclic amide group known as beta-lactam.
The ring consists of 1 nitrogen and 3 carbon atoms – these parts are responsible for antibacterial properties.
structure of penicillin: unusual structure of beta-lactam
bond angles are reduced to 90-degrees, and despite having sp2 and sp3 hybridised atomic orbitals the angles seek to form bonds with angles of 120-degrees and 109.5-degrees
disadvantages of penicillin 2
- broken down by stomach acid = has to be injected into bloodstream
- use is limited bc sig. no. of ppl have allergic responses
areas of body for action of penicillin
infections in
- ear
- nose
- throat
- mouth
- wound infections
whats up with some bacteria having antibiotic resistance? like how
-beta-lactam ring – crucial to penicillin’s antibacterial action = ring broken = no activity
- shown in some bacteria: produce an enzyme, penicillinase – can open the ring = inactive.
responses to antibiotic resistance
- discourage over prescription: make it prescription only
- synthesis of different forms of penicillin to withstand the action of penicillinase eg methicillin
- education of patients of the importance of completing the full course of treatment with an antibiotic = patient compliance
describe the process of penicillin action 4
- disrupt formation of cell walls of bacteria by inhibiting bacterial enzyme transpeptidase.
- High reactivity of amide group in ring causes it to bind irreversibly near the active site of the enzyme as the ring breaks.
- Inactivation of enzyme blocks cell wall construction within the bacterium.
- Cell walls unable to support the bacterium = bursts and dies.
how to describe the action of penicillin in a structural equation type beat
the enzyme –> corner of square connected to =O, arrows from the corner to O and N
becomes N-, breaks that bond.
corner becomes C, enzyme (E) is connected to it
brefily describe penicillin and aspirin
penicillin: an early antibiotic
aspirin: a mild analgesic (pain relief)
how does pain work
nerve messages sent from various pain receptors – stimulated by Prostaglandins
what are prostaglandins and what do they do
- released from cells damaged thermally/mechanically/chemically
- mediates inflammatory response – causes dilation of blood vessels near injury
- leads to swelling and incr pain
- affects temp regulation = can cause Fever
describe action of aspirin
- prevents stimulation of nerve endings at site of pain
- inhibits release of prostaglandins from injury site
= intercepts/blocks pathway between source and receptors of pain
does aspirin interfere with brain function?
no = known as non-narcotics
development of aspirin
- 400BCE –> chewing willow bark for pain/fever relief
- early 1800s –> active ingredient in bark is salicin, salicylic acid for treatment
- 1890 –> bayer company in germany: made ester derivative – aspirin
how is aspirin synthesised
Salicylic acid is converted into aspirin through esterification (condensation reaction). Process usually uses ethanoic anhydride, (CH3CO)2O.
conc sulfuric acid / phosphoric acid added –> mixture is warmed gently –> cooled to form crystals –> suction filtered and washed with chilled water.
= prevents loss of product (low solubility of aspirin at low temp)
word equation for synthesis of aspirin bc i cant add the chem one withot pics
salicylic acid + ethanoic anhydride –> aspirin + ethanoic acid
how has aspirin been modified for absorption and distribtion
- avail in many formations: various coatings, buffer components
= delay activity until its in small intestine = alleviates some side effects
how is aspirin purified
- recrystallisation –> dissolving impure crystals in min. vol. of hot ethanol (better solvent for impurities)
= forms saturated aspirin –> cooled slowly –> aspirin crystalises out first –> seperated by filtration
how is purity of aspirin determined
melting point determination
- pure substance: aspirin 138-140 degC, salicylic 159 degC
- mixture: lower, less defined melting point
infrared spectrascopy (IR) of aspirin
- used to characterise – absorption of particular wavenumbers of IR radiation – helps identify presence of certain functional grps
- early on OH trough: for –OH in acid
- 2 large spikes starting at around 1800, left: ester grp, right: C=O in acid
synergistic effects of ethanol and aspirin
more acute physiological effects – synergy (care advised when consm. alcohol w meds)
- can cause incr bleeding of stomach lining, incr risk of ulcers
positive physiological effects of aspirin 2
- anticoagulant – reduces bloods ability to clot
- useful for patients at risk of heart disease, stroke
- potentially dangerous for ppl whose blood does not clot easily - regular intake of low doses – may reduce risk of colon cancer
negative physiological effects of aspirin 3
- irritation, even dev of ulcers in stomach, duodenum – possible bleeding
- large no. of ppl esp. asthma – allergic to aspirin
- linked to Reye’s syndrome in children under 12 (liver + brain disorder, po. fatal)
