Penicillin is one the world’s first antibiotic agents, discovered accidently by a Scottish bacteriologist who goes by the name Alexander Fleming in 1928. The drugs are also the most widely used antibiotic agents to this day. They include penicillin G, penicillin V, procaine penicillin and benzathine penicillin. They all derive from the same source which is penicillium mold (fungus), and when isolated in a fluid medium, it produces a substance capable enough of killing many common bacteria that infected humans. Primarily penicillin molecular formula is written as C9H11N2O4S.
Previously stating, penicillin was discovered accidently by Alexander Fleming. Fleming had just return from a vacation and he and his family were sorting out the petri dishes he isolated on his work desk. While sterilizing petri dishes one in particular caught his attention. Fleming accidentally left a dish of staphylococcus bacteria uncovered for a few days. He returned to find the dish coated with bacterial growth, except from a particular area where a patch of mold (penicillium) was growing which left a bacteria free zone. Conclusively this was the stepping stone on the development of the antibiotic penicillin we know today.
Fleming’s discovery went dormant for a short period of time before researchers from Oxford took the opportunity to examine the chemical properties and the characteristics to develop ideas to make penicillin a medical phenomenon. The two scientists were Howard Florey an Australian scientist and Ernst Boris Chain a German who fled Germany during WW2 to work as a scientist in England.
Now looking at penicillin at a microscopic level we can view its function precisely. Penicillin’s are bactericidal antibiotics, as their main function comprises of killing microorganisms. The synthesis of the cell wall of bacteria is dependent on the enzyme transpeptidas. Penicillin inhibits the formation of the cell wall as it blocks transpeptidase from binding to a specific protein called penicillin binding protein (PBP), and as a result the bacteria cells die from cell lysis. Penicillin doesn’t kill other cells in the human body as our cells don’t contain a cell wall.
Furthermore, the chemistry and fundamental structure around penicillin gives us a better understanding on how penicillin functions in different environments. Pharmacophore is “a part of a molecular structure that is responsible for a particular biological or pharmacological interaction that it undergoes”. Therefore the pharmacophore of penicillin’s is known as the penicillin nucleus. The three fundamental structure requirements are the ?-lactam ring & thiazolidine ring structure, a free carboxyl acid group and a minimum of one amino acid side chain.
The most vital structure is the ?-lactam ring. This is a four membered cyclic amide that is unstable in both acidic and alkaline environments. As the ring is under a colossal amount of stress, the amide group is more susceptible to hydrolysis, which results in the formation of open chained compound.
Overtime bacteria can become resistant to penicillin due to many reasons one being frequent prescriptions, the more antibiotic used the more resistant the bacteria becomes. This is due to the weaker bacteria dying and leaving the stronger bacteria that can resist the treatment to grow and multiply. ?-Lactamase is an enzyme produced by some penicillin resistant bacteria which disrupts the ?-lactam ring resulting in a non-functioning antibiotic. However the with the introduction of the compound clavulanic acid the penicillin can function again. Conclusively clavulanic acid allows penicillin to function by inhibiting the enzyme that makes the bacteria resistant to penicillin which is ?-lactamase.