Penicillin

For the Japanese band, see Penicillin (band).
Penicillin core structure, where "R" is the variable group.

Penicillin (sometimes abbreviated PCN or pen) is a group of antibiotics derived from Penicillium fungi,[1] including penicillin G (intravenous use), penicillin V (oral use), procaine penicillin, and benzathine penicillin (intramuscular use).

Penicillin antibiotics were among the first drugs to be effective against many previously serious diseases, such as bacterial infections caused by staphylococci and streptococci. Penicillins are still widely used today, though misuse has now made many types of bacteria resistant. All penicillins are β-lactam antibiotics and are used in the treatment of bacterial infections caused by susceptible, usually Gram-positive, organisms.

Several enhanced penicillin families also exist, effective against additional bacteria: these include the antistaphylococcal penicillins, aminopenicillins and the more-powerful antipseudomonal penicillins.

Medical uses

The term "penicillin" is often used generically to refer to benzylpenicillin (penicillin G, the original penicillin found in 1928), procaine benzylpenicillin (procaine penicillin), benzathine benzylpenicillin (benzathine penicillin), and phenoxymethylpenicillin (penicillin V). Procaine penicillin and benzathine penicillin have the same antibacterial activity as benzylpenicillin but act for a longer period of time. Phenoxymethylpenicillin is less active against gram-negative bacteria than benzylpenicillin.[2][3] Benzylpenicillin, procaine penicillin and benzathine penicillin are given by injection (parenterally), but phenoxymethylpenicillin is given orally.

Susceptibility

Despite the expanding number of penicillin resistant bacteria, penicillin can still be used to treat a wide range of infections caused by certain susceptible bacteria. Some of these bacteria include Streptococci, Staphylococci, Clostridium, and Listeria genera. The following list illustrates minimum inhibitory concentration susceptibility data for a few medically significant bacteria:[4][5]

Adverse effects

Common adverse drug reactions (≥ 1% of patients) associated with use of the penicillins include diarrhoea, hypersensitivity, nausea, rash, neurotoxicity, urticaria, and superinfection (including candidiasis). Infrequent adverse effects (0.1–1% of patients) include fever, vomiting, erythema, dermatitis, angioedema, seizures (especially in people with epilepsy), and pseudomembranous colitis.[6]

Mechanism of action

Bacteria that attempt to grow and divide in the presence of penicillin fail to do so, and instead end up shedding their cell walls.
Penicillin and other β-lactam antibiotics act by inhibiting penicillin-binding proteins, which normally catalyze cross-linking of bacterial cell walls.

Bacteria constantly remodel their peptidoglycan cell walls, simultaneously building and breaking down portions of the cell wall as they grow and divide. β-Lactam antibiotics inhibit the formation of peptidoglycan cross-links in the bacterial cell wall; this is achieved through binding of the four-membered β-lactam ring of penicillin to the enzyme DD-transpeptidase. As a consequence, DD-transpeptidase cannot catalyze formation of these cross-links, and an imbalance between cell wall production and degradation develops, causing the cell to rapidly die.

The enzymes that hydrolyze the peptidoglycan cross-links continue to function, even while those that form such cross-links do not. This weakens the cell wall of the bacterium, and osmotic pressure becomes increasingly uncompensated—eventually causing cell death (cytolysis). In addition, the build-up of peptidoglycan precursors triggers the activation of bacterial cell wall hydrolases and autolysins, which further digest the cell wall's peptidoglycans. The small size of the penicillins increases their potency, by allowing them to penetrate the entire depth of the cell wall. This is in contrast to the glycopeptide antibiotics vancomycin and teicoplanin, which are both much larger than the penicillins.[7]

Gram-positive bacteria are called protoplasts when they lose their cell walls. Gram-negative bacteria do not lose their cell walls completely and are called spheroplasts after treatment with penicillin.

Penicillin shows a synergistic effect with aminoglycosides, since the inhibition of peptidoglycan synthesis allows aminoglycosides to penetrate the bacterial cell wall more easily, allowing their disruption of bacterial protein synthesis within the cell. This results in a lowered MBC for susceptible organisms.

Penicillins, like other β-lactam antibiotics, block not only the division of bacteria, including cyanobacteria, but also the division of cyanelles, the photosynthetic organelles of the glaucophytes, and the division of chloroplasts of bryophytes. In contrast, they have no effect on the plastids of the highly developed vascular plants. This supports the endosymbiotic theory of the evolution of plastid division in land plants.[8]

The chemical structure of penicillin is triggered with a very precise, pH-dependent directed mechanism, effected by a unique spatial assembly of molecular components, which can activate by protonation. It can travel through bodily fluids, targeting and inactivating enzymes responsible for cell-wall synthesis in gram-positive bacteria, meanwhile avoiding the surrounding non-targets. Penicillin can protect itself from spontaneous hydrolysis in the body in its anionic form, while storing its potential as a strong acylating agent, activated only upon approach to the target transpeptidase enzyme and protonated in the active centre. This targeted protonation neutralizes the carboxylic acid moiety, which is weakening of the β-lactam ring N–C(=O) bond, resulting in a self-activation. Specific structural requirements are equated to constructing the perfect mouse trap for catching targeted prey.[9]

Structure

Chemical structure of Penicillin G. The sulfur and nitrogen of the five-membered thiazolidine ring are shown in yellow and blue respectively. The image shows that the thiazolidine ring and fused four-membered β-lactam are not in the same plane.

The term "penam" is used to describe the common core skeleton of a member of the penicillins. This core has the molecular formula R-C9H11N2O4S, where R is the variable side chain that differentiates the penicillins from one another. The penam core has a molecular weight of 243 g/mol, with larger penicillins having molecular weights near 450—for example, cloxacillin has a molecular weight of 436 g/mol. The key structural feature of the penicillins is the four-membered β-lactam ring; this structural moiety is essential for penicillin's antibacterial activity. The β-lactam ring is itself fused to a five-membered thiazolidine ring. The fusion of these two rings causes the β-lactam ring to be more reactive than monocyclic β-lactams because the two fused rings distort the β-lactam amide bond and therefore remove the resonance stabilisation normally found in these chemical bonds.[10]

Biosynthesis

Penicillin G biosynthesis

Overall, there are three main and important steps to the biosynthesis of penicillin G (benzylpenicillin).

Production

Penicillin is a secondary metabolite of certain species of Penicillium and is produced when growth of the fungus is inhibited by stress. It is not produced during active growth. Production is also limited by feedback in the synthesis pathway of penicillin.

α-ketoglutarate + AcCoA → homocitrate → L-α-aminoadipic acid → L-lysine + β-lactam

The by-product, l-lysine, inhibits the production of homocitrate, so the presence of exogenous lysine should be avoided in penicillin production.

The Penicillium cells are grown using a technique called fed-batch culture, in which the cells are constantly subject to stress, which is required for induction of penicillin production. The available carbon sources are also important: Glucose inhibits penicillin production, whereas lactose does not. The pH and the levels of nitrogen, lysine, phosphate, and oxygen of the batches must also be carefully controlled.

The biotechnological method of directed evolution has been applied to produce by mutation a large number of Penicillium strains. These techniques include error-prone PCR, DNA shuffling, ITCHY, and strand-overlap PCR.

Semisynthetic penicillins are prepared starting from the penicillin nucleus 6-APA.

History

Discovery

Main article: History of penicillin
Alexander Fleming, who is credited with discovering penicillin in 1928.
Sample of penicillium mould presented by Alexander Fleming to Douglas Macleod, 1935

In 1897 a French physician, Ernest Duchesne at École du Service de Santé Militaire in Lyons, published a medical thesis entitled Contribution à l’étude de la concurrence vitale chez les micro-organismes : antagonisme entre les moisissures et les microbes (Contribution to the study in vital competition in microorganisms: antagonism between molds and microbes) in which he specifically studied the interaction between Escherichia coli and Penicillium glaucum. He independently discovered healing properties of P. glaucum, even curing infected guinea pigs from typhoid. His dissertation[16] was ignored by the Institut Pasteur. Although he is the precursor to antibiotic-mediated therapy and penicillin in particular, his works were subsequently forgotten.[17] Italian physician Vincenzo Tiberio from the University of Naples published a study on the effects of this mold that he saw in a well near his house in Arzano, Italy, in 1985.[18][19][20]

The discovery of penicillin is attributed to Scottish scientist and Nobel laureate Alexander Fleming in 1928.[21] He showed that, if Penicillium rubens[22] were grown in the appropriate substrate, it would exude a substance with antibiotic properties, which he dubbed penicillin. This serendipitous observation began the modern era of antibiotic discovery. The development of penicillin for use as a medicine is attributed to the Australian Nobel laureate Howard Walter Florey, together with the German Nobel laureate Ernst Chain and the English biochemist Norman Heatley.[23]

Fleming recounted that the date of his discovery of penicillin was on the morning of Friday, September 28, 1928.[24] The traditional version of this story describes the discovery as a fortuitous accident: in his laboratory in the basement of St Mary's Hospital in London (now part of Imperial College), Fleming noticed a Petri dish containing Staphylococcus that had been mistakenly left open, was contaminated by blue-green mould from an open window, which formed a visible growth.[25] There was a halo of inhibited bacterial growth around the mould. Fleming concluded that the mould released a substance that repressed the growth and caused lysing of the bacteria.[23]

Scientists now suspect that Fleming’s story of the initial discovery of the antibacterial properties of the penicillium mould is inaccurate. With a modern understanding of how the bacteria and the mould interact, scientists know that if bacteria were already present on the petri dish they would have inhibited the growth of the mould and Fleming would not have noticed any mould on the plate at all. A more likely story is that a spore from a laboratory one floor below, run by C. J. La Touche, was transferred to Fleming's petri dish before the bacteria were added. At the time of the initial discovery La Touche was working with the same mould found in Fleming's petri dish.[25]

Once Fleming made his discovery he grew a pure culture and discovered it was a Penicillium mould, now known to be Penicillium notatum. Fleming coined the term "penicillin" to describe the filtrate of a broth culture of the Penicillium mould. Fleming asked C. J. La Touche to help identify the mould, which he incorrectly identified as Penicillium rubrum (later corrected by Charles Thom). He expressed initial optimism that penicillin would be a useful disinfectant, because of its high potency and minimal toxicity in comparison to antiseptics of the day, and noted its laboratory value in the isolation of Bacillus influenzae (now called Haemophilus influenzae).[26][25]

Fleming was a famously poor communicator and orator, which meant his findings were not initially given much attention.[25] He was unable to convince a true chemist to help him extract and stabilize the antibacterial compound found in the broth filtrate. Despite the lack of a true chemist, he remained interested in the potential use of penicillin and presented a paper entitled "A Medium for the Isolation of Pfeiffer’s Bacillus" to the medical research club of London, which was met with little interest and even less enthusiasm by his peers. Had Fleming been more successful at making other scientists interested in his work, penicillin for medicinal use would possibly have been developed years earlier.[25]

Despite the lack of interest of his fellow scientists, he did conduct several experiments on the antibiotic substance he discovered. The most important result proved it was nontoxic in humans by first performing toxicity tests in animals and then on humans. His following experiments on penicillin's response to heat and pH allowed Fleming to increase the stability of the compound.[26] The one test that modern scientists would find missing from his work was the test of penicillin on an infected animal, the results of which would likely have sparked great interest in penicillin and sped its development by almost a decade.[25]

Medical application

Florey (pictured), Fleming and Chain shared a Nobel Prize in 1945 for their work on penicillin.

In 1930, Cecil George Paine, a pathologist at the Royal Infirmary in Sheffield, attempted to use penicillin to treat sycosis barbae, eruptions in beard follicles, but was unsuccessful. Moving on to ophthalmia neonatorum, a gonococcal infection in infants, he achieved the first recorded cure with penicillin, on November 25, 1930. He then cured four additional patients (one adult and three infants) of eye infections, and failed to cure a fifth.[27][28][29]

In 1939, Australian scientist Howard Florey (later Baron Florey) and a team of researchers (Ernst Boris Chain, Arthur Duncan Gardner, Norman Heatley, M. Jennings, J. Orr-Ewing and G. Sanders) at the Sir William Dunn School of Pathology, University of Oxford made progress in showing the in vivo bactericidal action of penicillin. In 1940 they showed that penicillin effectively cured bacterial infection in mice.[30][31] In 1941 they treated a policeman, Albert Alexander, with a severe face infection; his condition improved, but then supplies of penicillin ran out and he died. Subsequently, several other patients were treated successfully.[32]

Mass production

A technician preparing penicillin in 1943

By late 1940, the Oxford team under Howard Florey had devised a method of mass-producing the drug, but yields remained low.[32] In 1941, Florey and Heatley traveled to the U.S. in order to interest pharmaceutical companies in producing the drug and inform them about their process.[32]

Florey and Chain shared the 1945 Nobel Prize in Medicine with Fleming for their work.

The challenge of mass-producing this drug was daunting. On March 14, 1942, the first patient was treated for streptococcal septicemia with US-made penicillin produced by Merck & Co.[33] Half of the total supply produced at the time was used on that one patient. By June 1942, just enough US penicillin was available to treat ten patients.[34] In July 1943, the War Production Board drew up a plan for the mass distribution of penicillin stocks to Allied troops fighting in Europe.[35] The results of fermentation research on corn steep liquor at the Northern Regional Research Laboratory at Peoria, Illinois, allowed the United States to produce 2.3 million doses in time for the invasion of Normandy in the spring of 1944. After a worldwide search in 1943, a mouldy cantaloupe in a Peoria, Illinois market was found to contain the best strain of fungus for production using the corn steep liquor process.[36] Large-scale production resulted from the development of deep-tank fermentation by chemical engineer Margaret Hutchinson Rousseau.[37] As a direct result of the war and the War Production Board, by June 1945, over 646 billion units per year were being produced.[35]

Penicillin was being mass-produced in 1944.

G. Raymond Rettew made a significant contribution to the American war effort by his techniques to produce commercial quantities of penicillin.[38] During World War II, penicillin made a major difference in the number of deaths and amputations caused by infected wounds among Allied forces, saving an estimated 12%–15% of lives. Availability was severely limited, however, by the difficulty of manufacturing large quantities of penicillin and by the rapid renal clearance of the drug, necessitating frequent dosing. Methods for mass production of penicillin were patented by Andrew Jackson Moyer in 1945.[39][40][41] Florey had not patented penicillin, having been advised by Sir Henry Dale that doing so would be unethical.[32]

Penicillin is actively excreted, and about 80% of a penicillin dose is cleared from the body within three to four hours of administration. Indeed, during the early penicillin era, the drug was so scarce and so highly valued that it became common to collect the urine from patients being treated, so that the penicillin in the urine could be isolated and reused.[42] This was not a satisfactory solution, so researchers looked for a way to slow penicillin excretion. They hoped to find a molecule that could compete with penicillin for the organic acid transporter responsible for excretion, such that the transporter would preferentially excrete the competing molecule and the penicillin would be retained. The uricosuric agent probenecid proved to be suitable. When probenecid and penicillin are administered together, probenecid competitively inhibits the excretion of penicillin, increasing penicillin's concentration and prolonging its activity. Eventually, the advent of mass-production techniques and semi-synthetic penicillins resolved the supply issues, so this use of probenecid declined.[42] Probenecid is still useful, however, for certain infections requiring particularly high concentrations of penicillins.[6]

After World War II, Australia was the first country to make the drug available for civilian use. In the U.S., penicillin was made available to the general public on March 15, 1945.[43]

Dorothy Hodgkin determined the chemical structure of penicillin.

Structure determination and total synthesis

In 1945 the chemical structure of penicillin was determined using X-ray crystallography by Dorothy Crowfoot Hodgkin, who was also working at Oxford.[44] She later received the Nobel prize for this and other structure determinations.

Chemist John C. Sheehan at the Massachusetts Institute of Technology (MIT) completed the first chemical synthesis of penicillin in 1957.[45][46][47] Sheehan had started his studies into penicillin synthesis in 1948, and during these investigations developed new methods for the synthesis of peptides, as well as new protecting groups—groups that mask the reactivity of certain functional groups.[47][48] Although the initial synthesis developed by Sheehan was not appropriate for mass production of penicillins, one of the intermediate compounds in Sheehan's synthesis was 6-aminopenicillanic acid (6-APA), the nucleus of penicillin.[47][49][50] Attaching different groups to the 6-APA 'nucleus' of penicillin allowed the creation of new forms of penicillin.

Developments from penicillin

The narrow range of treatable diseases or "spectrum of activity" of the penicillins, along with the poor activity of the orally active phenoxymethylpenicillin, led to the search for derivatives of penicillin that could treat a wider range of infections. The isolation of 6-APA, the nucleus of penicillin, allowed for the preparation of semisynthetic penicillins, with various improvements over benzylpenicillin (bioavailability, spectrum, stability, tolerance).

The first major development was ampicillin in 1961. It offered a broader spectrum of activity than either of the original penicillins. Further development yielded β-lactamase-resistant penicillins, including flucloxacillin, dicloxacillin, and methicillin. These were significant for their activity against β-lactamase-producing bacterial species, but were ineffective against the methicillin-resistant Staphylococcus aureus (MRSA) strains that subsequently emerged.

Another development of the line of true penicillins was the antipseudomonal penicillins, such as carbenicillin, ticarcillin, and piperacillin, useful for their activity against Gram-negative bacteria. However, the usefulness of the β-lactam ring was such that related antibiotics, including the mecillinams, the carbapenems and, most important, the cephalosporins, still retain it at the center of their structures.[51]

See also

Notes

  1. ↑ Penicillin at the Free Dictionary
  2. ↑ Garrod, L. P. (1960). "Relative Antibacterial Activity of Three Penicillins". British Medical Journal 1 (5172): 527–29. doi:10.1136/bmj.1.5172.527.
  3. ↑ Garrod, L. P. (1960). "The Relative Antibacterial Activity of Four Penicillins". British Medical Journal 2 (5214): 1695–6. doi:10.1136/bmj.2.5214.1695. PMC 2098302. PMID 13703756.
  4. ↑ "Penicillin (Benzylpenicillin, Penicillin G, Bicillin C-R/L-A, Pfizerpen, Wycellin)". The Antimicrobial Index. Knowledgebase. Retrieved 4 March 2014.
  5. ↑ "Penicillin G sodium salt Susceptibilty and Resistance Data" (PDF). TOKU-E. Retrieved 4 March 2014.
  6. ↑ 6.0 6.1 Rossi S, editor, ed. (2006). Australian Medicines Handbook. Adelaide: Australian Medicines Handbook. ISBN 0-9757919-2-3.
  7. ↑ http://www.facm.ucl.ac.be/Full-texts-FACM/Vanbambeke-1999-3.pdf
  8. ↑ Kasten, Britta; Reski, Ralf (March 30, 1997). "β-lactam antibiotics inhibit chloroplast division in a moss (Physcomitrella patens) but not in tomato (Lycopersicon esculentum)". Journal of Plant Physiology 150 (1–2): 137–140. doi:10.1016/S0176-1617(97)80193-9.
  9. ↑ Mucsi, z; Chass, GA; Ábrányi-Balogh, P; Jójárt, B; Fang, DC; Ramirez-Cuesta, AJ; Viskolcz, B; Csizmadia, IG (2013). "Penicillin's catalytic mechanism revealed by inelastic neutrons and quantum chemical theory". Phys Chem Chem Phys 15 (47): 20447–20455. doi:10.1039/c3cp50868d. PMID 23760063.
  10. ↑ Nicolaou (1996), pg. 43.
  11. ↑ 11.0 11.1 11.2 Al-Abdallah, Q., Brakhage, A. A., Gehrke, A., Plattner, H., Sprote, P., Tuncher, A. (2004). "Regulation of Penicillin Biosynthesis in Filamentous Fungi". In Brakhage AA. Molecular Biotechnolgy of Fungal beta-Lactam Antibiotics and Related Peptide Synthetases (88). pp. 45–90. doi:10.1007/b99257. ISBN 3-540-22032-1.
  12. ↑ 12.0 12.1 Brakhage, A. A. (1998). "Molecular Regulation of β-Lactam Biosynthesis in Filamentous Fungi". Microbiol Mol Biol Rev. 62 (3): 547–85. PMC 98925. PMID 9729600.
  13. ↑ Baldwin, J. E., Byford, M. F., Clifton, I., Hajdu, J., Hensgens, C., Roach, P, Schofield, C. J.; Baldwin; Byford; Clifton; Hajdu; Hensgens; Roach (1997). "Proteins of the Penicillin Biosynthesis Pathway". Current Opinion in Structural Biology 7 (6): 857–64. doi:10.1016/s0959-440x(97)80158-3. PMID 9434907.
  14. ↑ 14.0 14.1 Fernandez, F. J., Fierro, F., Gutierrez, S, Kosalkova, K . Marcos, A. T., Martin, J. F., Velasco, J.; Gutiérrez; Fernández; Velasco; Fierro; Marcos; Kosalkova (September 1994). "Expression of Genes and Processing of Enzymes for the Biosynthesis of Penicillins and Cephalosporms". Anton Van Lee 65 (3): 227–43. doi:10.1007/BF00871951. PMID 7847890.
  15. ↑ Baker, W. L., Lonergan, G. T. "Chemistry of Some Fluorescamine-Amine Derivatives with Relevance to the Biosynthesis of Benzylpenicillin by Fermentation". J Chem Technol Biot. 2002, 77, pp1283-1288.
  16. ↑ Duchesne 1897, Antagonism between molds and bacteria. An English translation by Michael Witty. Fort Myers, 2013. ASIN B00E0KRZ0E and B00DZVXPIK.
  17. ↑ Une découverte oubliée : la thèse de médecine du docteur Ernest Duchesne (1874–1912)
  18. ↑ Tiberio V. Sugli estratti di alcune muffe [On certain mold extracts]. Ann Ig Sperim 1895;1:91-102.
  19. ↑ (EN) Bucci R., Galli P., Vincenzo Tiberio: a misunderstood researcher Journal of Public Health, vol. 8, no. 4, IX (2011), pp. 404-406 (Accessed 1 May 2015)
  20. ↑ Migali C.: Gli antibiotici? Una scoperta italiana in Almanacco della Scienza CNR - Rivista OnLine (Accessed 1 May 2015)
  21. ↑ "Alexander Fleming – Time 100 People of the Century". Time. It was a discovery that would change the course of history. The active ingredient in that mold, which Fleming named penicillin, turned out to be an infection-fighting agent of enormous potency. When it was finally recognized for what it is—the most efficacious life-saving drug in the world—penicillin would alter forever the treatment of bacterial infections.
  22. ↑ Houbraken J, Frisvad JC, Samson RA; Frisvad; Samson (2011). "Fleming's penicillin producing strain is not Penicillium chrysogenum but P. rubens". IMA Fungus 2 (1): 87–95. doi:10.5598/imafungus.2011.02.01.12. PMC 3317369. PMID 22679592.
  23. ↑ 23.0 23.1 Bud, Robert (2009). Penicillin: Triumph and Tragedy. Oxford University Press. ISBN 978-0199541614.
  24. ↑ Haven, Kendall F. (1994). Marvels of Science : 50 Fascinating 5-Minute Reads. Littleton, CO: Libraries Unlimited. p. 182. ISBN 1-56308-159-8.
  25. ↑ 25.0 25.1 25.2 25.3 25.4 25.5 Lax, Eric (2004). The Mold in Dr. Florey's Coat: The Story of the Penicillin Miracle. Holt Paperbacks. ISBN 978-0805077780.
  26. ↑ 26.0 26.1 Fleming A. (1929). "On the antibacterial action of cultures of a penicillium, with special reference to their use in the isolation of B. influenzæ". British Journal of Experimental Pathology 10 (31): 226–236. PMC 2566493.
  27. ↑ Wainwright M, Swan HT; Swan (January 1986). "C.G. Paine and the earliest surviving clinical records of penicillin therapy". Medical History 30 (1): 42–56. doi:10.1017/S0025727300045026. PMC 1139580. PMID 3511336.
  28. ↑ Howie, J (1986). "Penicillin: 1929-40". British Medical Journal (Clinical research ed.) 293 (6540): 158–159. doi:10.1136/bmj.293.6540.158. PMC 1340901.
  29. ↑ Wainwright, M (1987). "The history of the therapeutic use of crude penicillin". Medical History 31 (1): 41–50. doi:10.1017/s0025727300046305. PMC 1139683. PMID 3543562.
  30. ↑ Clark, Ronald (1985). The Life of Ernst Chain: Penicillin and Beyond.
  31. ↑ "Animal Experiments: Further Views". New York Times. 1992-05-24. Retrieved 2014-10-11.
  32. ↑ 32.0 32.1 32.2 32.3 "Making Penicillin Possible: Norman Heatley Remembers". ScienceWatch. Thomson Scientific. 2007. Archived from the original on 21 February 2007. Retrieved 2007-02-13.
  33. ↑ The First Use of Penicillin in the United States, by Charles M. Grossman. Annals of Internal Medicine July 15, 2008: Volume 149, Issue 2, Pages 135–136.
  34. ↑ John S. Mailer, Jr., and Barbara Mason. "Penicillin : Medicine's Wartime Wonder Drug and Its Production at Peoria, Illinois". lib.niu.edu. Retrieved February 11, 2008.
  35. ↑ 35.0 35.1 John Parascandola (1980). The History of antibiotics: a symposium. American Institute of the History of Pharmacy No. 5. ISBN 0-931292-08-5.
  36. ↑ Mary Bellis. "The History of Penicillin". Inventors. About.com. Retrieved October 30, 2007.
  37. ↑ Chemical Heritage Manufacturing a Cure: Mass Producing Penicillin
  38. ↑ "ExplorePAhistory.com". Retrieved May 11, 2009.
  39. ↑ Andrew Jackson Moyer, Method for Production of Penicillin, United States Patent Office, US Patent 2,442,141, filed 11 May 1945, issued 25 March 1948.
  40. ↑ Andrew Jackson Moyer, Method for Production of Penicillin, United States Patent Office, US Patent 2,443,989, filed 11 May 1945, issued 22 June 1948.
  41. ↑ Andrew Jackson Moyer, Method for Production of Penicillin, United States Patent Office, US Patent 2,476,107, filed 11 May 1945, issued 12 July 1949.
  42. ↑ 42.0 42.1 Silverthorn, DU. (2004). Human physiology: an integrated approach. (3rd ed.). Upper Saddle River (NJ): Pearson Education. ISBN 0-8053-5957-5.
  43. ↑ "Discovery and development of penicillin". American Chemical Society. 1999.
  44. ↑ The Nobel Prize in Chemistry 1964, Perspectives. Retrieved July 14, 2012.
  45. ↑ Sheehan, John C.; Henery-Logan, Kenneth R. (March 5, 1957). "The Total Synthesis of Penicillin V". Journal of the American Chemical Society 79 (5): 1262–1263. doi:10.1021/ja01562a063.
  46. ↑ Sheehan, John C.; Henery-Logan, Kenneth R. (June 20, 1959). "The Total Synthesis of Penicillin V". Journal of the American Chemical Society 81 (12): 3089–3094. doi:10.1021/ja01521a044.
  47. ↑ 47.0 47.1 47.2 E. J. Corey; John D. Roberts. "Biographical Memoirs: John Clark Sheehan". The National Academy Press. Retrieved January 28, 2013.
  48. ↑ Nicolaou, K.C.; Vourloumis, Dionisios; Winssinger, Nicolas; Baran, Phil S. (2000). "The Art and Science of Total Synthesis at the Dawn of the Twenty-First Century**". Angewandte Chemie International Edition 39 (1): 44–122. doi:10.1002/(SICI)1521-3773(20000103)39:1<44::AID-ANIE44>3.0.CO;2-L. PMID 10649349.
  49. ↑ "Professor John C. Sheehan Dies at 76". MIT News. April 1, 1992. Retrieved January 28, 2013.
  50. ↑ Sheehan, John C. (1982). The Enchanted Ring: The Untold Story of Penicillin. MIT Press. ISBN 978-0-262-19204-0.
  51. ↑ James, PharmD, Christopher W.; Cheryle Gurk-Turner, RPh (January 2001). "Cross-reactivity of beta-lactam antibiotics". Baylor University Medical Center Proceedings (Dallas, Texas: Baylor University Medical Center) 14 (1): 106–7. PMC 1291320. PMID 16369597.

References

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