DOXYCYCLINE

and other Tetracyclines

Why is it important?

In the wake of the attacks on the TwinTowers in New York on 11th September 2001, several letters containing anthrax spores were sent to two U. S. Senators and to various media outlets. Five people died of inhalational anthrax and seventeen others were taken ill. Bruce Edwards Ivins, a scientist at the U. S.government's bio-defence laboratories at Fort Detrick, Maryland, came under suspicion, and he committed suicide on July 27th 2008.

The anthrax outbreaks led to people suspected of exposure to anthrax being given the drug Cipro (Ciprofloxacin) but Doxycycline was recommended as an equally effective and cheaper alternative. Doxycycline (vibramycin) is effective against several diseases, including Yersinia pestis (bubonic plague), Lyme disease and Rocky Mountain spotted fever, as well as anthrax.

Is it a natural medicine?

Doxycycline is synthetic, but some tetracyclines are produced naturally by Streptomyces bacteria, such as chlorotetracycline (Aureomycin), which was the first one to be discovered; it was isolated from Streptomyces aurofaciens obtained from samples of Missouri soil in 1945 and marketed as a medicine in 1948.

In 1952 it was found that you could hydrogenate chlorotetracycline under mild conditions (H2; Pd/C catalyst) and produce tetracycline itself (link to October 2001 MOTM here). Pfizer isolated oxytetracycline from Streptomyces rimosus in the soil near their Indiana plant. A research team led by the great R. B. Woodward of Harvard went to work to solve the structure and published it in 1953.

Woodward picture at

or

Another Nobel laureate, D. H. R. Barton, said that “The most brilliant analysis ever done on a structural puzzle was surely the solution (1953) of the terramycin problem.”

Why were they being searched for?

At that time, a gold rush was on to discover antibiotics from natural sources.

Hadn’t penicillin just been discovered?

Chlorotetracycline had advantages over the other antibiotics that were available at the time (including penicillin) as it could be taken orally and was also effective against both Gram-positive and Gram-negative bacteria. By that time, resistance to penicillin had already been noted, so alternative antibiotics were a must.

How do you make doxycycline?

In 2005, Andrew Myers’ group at HarvardUniversitydescribed an 18-step synthesis, starting from benzoic acid.

The benzoic acid molecule forms the basis of the B ring of the doxycycline, around which the A, C and D rings are added by various ring-forming reactions. First the benzoic acid undergoes microbial dihydroxylation, followed by further steps including epoxidation and the introduction of protecting tert-butyldimethylsilyl groups (TBS) to afford an enantiomerically-pure epoxyester. A deprotonated dimethylamino substituted isoxazole is then added, subsequent ring closure in the successive reactions with lithium triflategenerating the A ring, and trifluoroacetic acid removing a TBS group. The C and D rings were then added by means of a coupling reaction with another carbanionic reagent via a Michael-Dieckmann sequence. Removal of the protecting groups (TBS = tert-butyldimethylsilyl; BOC = tert-butyloxycarbonyl, COtC4H9) afforded doxycycline, stereoselectively. The yield in this virtuoso demonstration of synthetic organic chemistry was 8.3%.

How do tetracyclines work?

Tetracyclines inhibit bacterial protein synthesis. They bind to the 16S part of the 30S subunit in the ribosome, and interfere with the binding of amino acylated tRNA, stopping the messenger-RNA codon reading the t-RNA anticodon. This is a key step of protein synthesis, and means that new aminoacids cannot be added to the nascent polypeptide chain. This explains why tetracyclines are effective against a wide range of both gram-positive and gram-negative bacteria.

So why don’t we hear more about them?

The tetracyclines are not used as widely as they once were, because of the emergence of resistant strains of bacteria. In part, this is due to the use of small amounts of antibiotics in animal feeds of animals such as pigs, chicken and cattle, in order to control disease and promote growth.

Apart from doxycycline, several tetracyclines still find wide application. Many members of the tetracycline family have been made by semisynthesis, using a naturally produced molecule to provide the core, then modifying its structure. Among the newer tetracyclines, tigecycline (Tygacil; 2005) is active against resistantbacteria such as Staphylococcus aureus.

Like other tetracyclines, minocycline is used as an oral antibiotic for acne, but in 2011 Canadian scientists carried out a screening of combinations of minocycline with other drugs and showed that a combination of minocycline with the well-known anti-diarrhoea drug loperamide was a potent antibacterial. Tests have not been carried out on human yet, but it is possible that such combinations could give new life to tetracyclines in medicine.

Recently Andrew Myers’ group have synthesised five-ring pentacyclines that show promise against pathogens that are resistant to some other medications.

But tetracyclines have actually been used for over 1500 years. It turns out that tetracycline was present in ancient Nubian beer and contributed to low rates of infectious disease.

I know that G------was good for you, but not Nubian beer!

The Nubian beer wasn’t like the present-day stuff; it was more like a syrupy gruel. 30 years ago, scientists at EmoryUniversity detected a green fluorescence when UV light was shone on bones from Nubian skeletons, dating from between 350 and 550 AD. This indicated the presence of tetracycline.

Reproduced by permission of Professor George J.Armelagos.

It was found that the beer was made by fermenting grain which contained streptomyces bacteria, found in soil. Further research indicated there were high levels of tetracycline in the bones of even small children. The ancient Nubians recognised the health effects of the beer and deliberately produced it, even if they did not know about tetracycline.

Acknowledgements Thanks are due to Professor George Armelagos of EmoryUniversity to reproduce an illustration, and to Professor James Anderson of UCL for advice.

Bibliography: -

Chapman and Hall Combined Chemical Dictionary compounds code numbers: -

tetracycline BDQ00-F; chlorotetracycline CKR88-Y; oxytetracycline CLB98-G; doxycycline BDT97-C; tigecycline KKB19-M; minocycline CKJ08-M (props, bibliography)

General

A. Gringauz, Introduction to Medicinal Chemistry: How Drugs Act and Why, New York, Wiley-Blackwell, 2nd edition, (1996), pp 243-247 (structure-activity relationship)

M. Nelson. W. Hillen and R.A. Greenwald (eds), Tetracyclines in Biology, Chemistry and Medicine, Basel, Birkhäuser Verlag, (2001).

G. L. Patrick, An Introduction to Medicinal Chemistry, 2nd edition, Oxford, OUP, (2001), pp 425-426.

J. Mann, Life Saving Drugs: The Elusive Magic Bullet, Cambridge, RSC, (2004), pp.70-71.

J. J. Li, Laughing Gas, Viagra, and Lipitor: The Human Stories Behind the Drugs We Use, New York, OUP USA, (2006), pp 67-69.

E. J. Corey, B. Czako and N. Kürti, Molecules and Medicine, Hoboken, New Jersey, (2007), p. 133.

K. C. Nicolaou and T. Montagnon, Molecules that changed the World, Weinheim, Wiley VCH, (2008), pp 290-291

Reviews

M. L. Nelson, Ann. Rep. Med. Chem., (2002), 37, 105- 114.

L. B. Pickens and Y. Tang, Metab. Eng., (2009), 11, 69-75 (biosynth rev.)

M. O. Griffin, E. Fricovsky, G. Ceballos and F. Villarreal, Am. J. Physiol CellPhysiol., (2010), 299, C539 - 548.

Synthesis of doxycycline

C. Khosla and Y. Tang, Science, (2005), 308, 367-368

M. G. Charest, C. D. Lerner, J. D. Brubaker, D. R. Siegel and A.G. Myers, Science, (2005), 308, 395-398.

D. F. Taber, Organic Chemistry Highlights, November 7 2005, at: -

Synthesis and biosynthesis of tetracyclines

F. A. Hochstein, C. R. Stephens, L. H. Conover, P. P. Regna, R. Pasternack, P. Gordon, F. J. Pilgrim, K. J. Brunings and R. B. Woodward, J. Am. Chem. Soc., (1953), 75, 5455–5475 (structure of terramycin, oxytetracycline)

L. H. Conover, K. Butler, J. D. Johnston, J. J. Korst and R. B. Woodward, J. Am. Chem. Soc., (1962), 84, 3222-3224 (total synth. of sancycline (6-demethyl-6-deoxytetracycline))

H. Muxfeldt, G. Hardtmann, F. Kathawala, E. Vedejs and J. B. Mooberry, J. Am. Chem. Soc., (1968), 90, 6534- 6536 (total synth. of terramycin)

J. D. Brubaker, D. R. Siegel and A.G. Myers, Org. Lett., (2007), 9, 3523-3525.

C. Sun, Q. Wang, J. D. Brubaker, P. M. Wright, C. D. Lerner, K. Noson, M. Charest, D. R. Siegel, Y.-M. Wang and A. G. Myers, J. Am. Chem. Soc., (2008), 130, 17913-17927.

C. Sun, D. Hunt, R. Clark, D. Lofland, W. O'Brien, L. Plamondon, and X.-Y. Xiao, J. Med. Chem., (2011),54, 3704–3731(pentacyclin)

Means of action of tetracycline

D. E. Brodersen,W. M. Clemons,A. P. Carter,R. J. Morgan-Warren,B. T. WimberlyandV. Ramakrishnan,Cell, (2000), 103, 1143-1154.

M. Pioletti, F. Schlünzen, J. Harms, R. Zarivach, M. Glühmann, H. Avila, A. Bashan, H. Bartels, T. Auerbach, C. Jacobi, T. Hartsch, A. Yonath and F. Franceschi, EMBO J., (2001), 20, 1829 – 1839. (cryst. struct. of tetracycline complex of the small ribosomal subunit)

Tetracyclines in combinational therapy.

L. Principe, S. D'Arezzo, A. Capone, N. Petrosillo and P. Visca, Ann. Clin. Microbiol. Antimicrob., (2009), 8, 18 – 27. (tigecycline)

L. Ejim, M. A. Farha, S. B Falconer, J. Wildenhain, B. K Coombes, M. Tyers, E. D. Brown and G. D. Wright, Nature Chem. Biol., (2011), 7, 348-350 (minocycline).

Tetracycline in Nubian bones and beer.

E. J. Bassett, M. S. Keith, G. J. Armelagos, D. L. Martin and A. R. Villanueva, Science, (1980),209, 1532–1534.

G. J. Armelagos, Natural History, (2000),109, 50-53.

G. J. Armelagos, K. Kolbacher, K. Collins, J. Cook andM. Krafeld-Daugbeny, Tetracycline consumption in prehistory, in M. Nelson. W. Hillen and R.A. Greenwald (eds), Tetracyclines in Biology, Chemistry and Medicine, Basel, Birkhauser Verlag, (2001), pp 219-236.

M. L. Nelson, A. Dinardo, J. Hochberg and G. J. Armelagos, Amer. J. Phys. Anthropol., (2010), 143, 151 – 154. (mass spec. characterization of tetracycline)

(summary)

Doxycycline

DOXYCYCLINE: AN OLD DRUG WITH A NEW ROLE IN IDIOPATHIC

PULMONARY FIBROSIS

GYANSHANKAR P. MISHRA AND JASMIN D. MULANI, Int. J. Pharma and Bio, Sci., 2010, 1, pp 1-6.

Tetracycline (INN) (/ˌtɛtrəˈsaɪkliːn/) is a broad-spectrum polyketideantibiotic produced by the Streptomycesgenus of Actinobacteria, indicated for use against many bacterial infections. It is a protein synthesis inhibitor. It is commonly used to treat acne today, and, more recently, rosacea, and played a historical role in reducing the incidence of mortality because of cholera. It is marketed under the brand names Sumycin, Terramycin, Tetracyn, and Panmycin, among others. Actisite is a thread-like fiber form, used in dental applications. It is also used to produce several semisynthetic derivatives, which together are known as the tetracycline antibiotics.

Contents

[hide]
  • 1Mechanism of action
  • 2History
  • 3Cautions, contraindications, side effects
  • 4Indications
  • 5Other uses
  • 6Cell culture
  • 7Notes

[edit]Mechanism of action

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Tetracyclines bind to the 30S subunit of microbial ribosomes. They inhibit protein synthesis by blocking the attachment of charged aminoacyl-tRNA. Thus they prevent introduction of new amino acids to the nascent peptide chain. The action is usually inhibitory and reversible upon withdrawal of the drug. Resistance to the tetracyclines results from changes in permeability of the microbial cell envelope. In susceptible cells, the drug is concentrated from the environment and does not readily leave the cell. In resistant cells, the drug is not actively transported into the cell or leaves it so rapidly that inhibitory concentrations are not maintained. This is often plasmid-controlled. Mammalian cells are not vulnerable to the effect of tetracyclines as these contain no 30S ribosomal subunit and therefore do not actively concentrate the drug. Tetracycline is also being used in recent years as a scar tissue remover. The Tetracycline breaks down scar tissue and promotes healthy skin growth that causes a semi-rapid normal skin tissue growth that makes any scars unnoticeable.

[edit]History

The tetracyclines are a large family of antibiotics that were discovered as natural products by Benjamin Minge Duggar and first described in 1948.[1] Under Yellapragada Subbarao, Benjamin Duggar made his discovery of the world's first tetracycline antibiotic, Aureomycin, in 1945.

In 1950, Harvard Professor Robert Woodward determined the chemical structure of Terramycin, the brand name for a member of the tetracycline family; the patent[2] protection for its fermentation and production was also first issued in 1950. A research team of seven scientists (Drs. K.J. Brunings, Francis A. Hochstein, C.R. Stephens, L.H. Conover, Abraham Bavley, Richard Pasternack, and Peter P. Regna) at Pfizer,[3][4] in collaboration with Woodward, participated in the two-year research leading to the discovery.[5]

Nubian mummies studied in the 1990s were found to contain significant levels of tetracycline; there is evidence that the beer brewed at the time could have been the source.[6] Tetracycline sparked the development of many chemically altered antibiotics, and in doing so has proved to be one of the most important discoveries made in the field of antibiotics.[citation needed] It is used to treat many Gram-positive and Gram-negative bacteria and some protozoa.[citation needed] It, like some other antibiotics, is also used in the treatment of acne.[citation needed]

[edit]Cautions, contraindications, side effects

Are as those of the tetracycline antibiotics group:[citation needed]

  • Can stain developing teeth (even when taken by the mother during pregnancy)
  • Can cause permanent teeth discoloration (yellow-gray-brown); infancy and childhood to eight years old
  • Inactivated by Ca2+ion, not to be taken with milk, yogurt, and other dairy products
  • Inactivated by aluminium, iron and zinc, not to be taken at the same time as indigestion remedies
  • Inactivated by common antacids and over-the-counter heartburn medicines
  • Skinphotosensitivity; exposure to the sun or intense light is not recommended
  • Drug-induced lupus, and hepatitis
  • Can induce microvesicular fatty liver.
  • Tinnitus
  • May interfere with methotrexate by displacing it from the various protein binding sites
  • Can cause breathing complications as well as anaphylactic shock in some individuals
  • Should be avoided during pregnancy as it may affect bone growth of the fetus
  • Passes into breast milk and is harmful to breast-fed infants, and should therefore be avoided during breastfeeding if possible[7]

In 2010, the FDA added tetracycline to its Adverse Event Reporting System (AERS).[8] The AERS contains a list of medications under investigation by the FDA for potential safety issues. The list is published quarterly and available online. The AERS cites a potential link between the use of tetracycline products and Stevens-Johnson syndrome, toxic epidermal necrolysis and erythema multiforme.[8]

[edit]Indications

It is first-line therapy for Rocky Mountain spotted fever (Rickettsia), Q fever (Coxiella), psittacosis and lymphogranuloma venereum (Chlamydia), and to eradicate nasal carriage of meningococci. Tetracycline tablets were used in the plague outbreak in India in 1992.[9]

Doxycycline is also one (of many) recommended drugs for chemoprophylatic treatment of malaria in travels to areas of the world where malaria is endemic.[10]

[edit]Other uses

Since tetracycline is absorbed into bone, it is used as a marker of bone growth for biopsies in humans. Tetracycline labeling is used to determine the amount of bone growth within a certain period of time, usually a period of approximately 21 days. Tetracycline is incorporated into mineralizing bone and can be detected by its fluorescence.[11] In double tetracycline labeling, a second dose is given 11–14 days after the first dose, and the amount of bone formed during that interval can be calculated by measuring the distance between the two fluorescent labels.[12]

Tetracycline is also used as a biomarker in wildlife to detect consumption of medicine- or vaccine-containing baits.[13]

In genetic engineering, tetracycline is used in transcriptional activation. Tetracycline is also one of the antibiotics used to treat ulcers caused by bacterial infections. In cancer research at HarvardMedicalSchool, tetracycline has been used to reliably cause regression of advanced stages of leukemia in mice, by placing it in their drinking water.[14]

[edit]Cell culture

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Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (January 2011)

Tetracycline is used in cell biology as selective agent in cell culture systems. It is toxic to prokaryotic and eukaryotic cells and selects for cells harboring the bacterial tetr gene, which encodes a 399-amino acid membrane-associated protein. This protein actively exports tetracycline out of the cell, rendering cells harboring this gene more resistant to the drug. The yellow crystalline powder can be dissolved in water (20mg/ml) or ethanol (5mg/ml) and is routinely used at 10mg/l in cell culture. In cell culture at 37°C (99°F), it is stable for days, half-life ~24 hours.

[edit]Notes

  1. ^ Klajn, Rafal, Chemistry and chemical biology of tetracyclines, retrieved 20 June 2007.
  2. ^U.S. Patent 2,516,080
  3. ^[1]
  4. ^"Scientists Discover Terramycin's Secret: Its Complex Structure".
  5. ^Hochstein, F. A.; Stephens, C. R.; Conover, L. H.; Regna, P. P.; Pasternack, R.; Gordon, P. N.; Pilgrim, F. J.; Brunings, K. J. et al. (November 1953). "The structure of terramycin". Journal of the American Chemical Society75 (22): 5455–75. doi:10.1021/ja01118a001.
  6. ^George Armelagos (May 2000). "Take Two Beers and Call Me in 1,600 Years - use of tetracycline by Nubians and Ancient Egyptians". AmericanMuseum of Natural History. Retrieved 2007-12-19.
  7. ^kidsgrowth.org --> Drugs and Other Substances in Breast Milk Retrieved on June 19, 2009
  8. ^ abFDA Adverse Events Reporting System Retrieved on January 14, 2011
  9. ^ Lippincott's Illustrated Reviews: Pharmacology, 4th ed. Harvery RA, Champe, PC. Lippincott, Williams & Wilkins, 2009
  10. ^Chapter 2 - Malaria - 2010 Yellow Book | CDC Travelers' Health
  11. ^ Mayton CA. Tetracycline labeling of bone
  12. ^The Johns Hopkins Medical Institutions. > Tetracycline Labeling Last updated January 8, 2001.
  13. ^Olson CA, Mitchell KD, Werner PA (October 2000). "Bait ingestion by free-ranging raccoons and nontarget species in an oral rabies vaccine field trial in Florida". J. Wildl. Dis.36 (4): 734–43. PMID11085436.
  14. ^William J. Cromie (February 10, 2000). "Researchers Switch Cancer Off and On -- In Mice". Retrieved 2008-10-25