User:TCO/Sandbox/Working: Fluorine

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Lead
Fluorine plays a very minor role in organismal biochemistry, but has many biological impacts resulting from man's use of the element. The carbon–fluorine chemical bond is the strongest bond in organic chemistry, and organofluorines are very stable. Save a few exceptions, the C–F bond does not exist in nature, meaning the entire field is essentially "man-made"; A very small number of plants and bacteria make monofluorinated compounds that are poisons, primarily monofluoroacetate. Fluorine is not a part of human or animal biochemistry, but the fluoride ion

Para on natural and bone and dental
 * Topic sentence on minor in biochemistry and major in applications.
 * Background on the carbon-fluorine bond of organic chemistry and formation (with refnote)
 * 40 organisms
 * bones and teeth

Para on medical
 * pharma (Lipitor and Prozac)
 * drug design
 * other classes
 * aenesthetics
 * PET scanning
 * liquid perfluorocarbon research

Para on agrichem and poisons and hazards
 * designed agrichemicals
 * fluoracetate

Para on hazards and biopersistance
 * fluorine
 * HF
 * fluoride
 * para on biopersistance

Biopersistance
Because of the strength of the carbon–fluorine bond, organofluorines endure in the environment. Perfluoroalkyl acids (PFAAs) have attracted particular attention as persistent global contaminants. These compounds can enter the environment from their direct uses in waterproofing treatments and firefighting foams or indirectly from leaks from fluoropolymer production plants (where they are intermediates). Because of the acid group, PFAAs are water soluble in low concentrations. While there are other PFAAs, the lion's share of environmental research has been done on the two most well-known: perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA). The U.S. Environmental Protection Agency classifies these materials as "emerging contaminants" based on the growing but still incomplete understanding of their environmental impact.

Trace quantities of PFAAs have been detected worldwide, from polar bears in the Arctic to the global human population. Both PFOS and PFOA has been detected in breast milk and the blood of newborns. A 2013 review showed widely varying amounts of PFOS and PFOA in different soils and groundwater, with no clear pattern of one chemical dominating. PFAA concentration was generally higher in areas with more human populations or industrial activity, and areas with more PFOS generally also had more PFOA. Human populations also showed different concentrations of the two chemicals; for example one study showed more PFOS than PFOA in Germans, while another study showed the reverse for Americans. PFAAs may be starting to decrease in the biosphere: one study indicated that PFOS levels in wildlife in Minnesota were going down, presumably because of ceased production of the chemical by 3M.

In the body, PFAAs bind to proteins such as serum albumin. Their tissue distribution in humans is unknown, but studies in rats suggest it is present mostly in the liver, kidney, and blood. They are not metabolized by the body but are excreted by the kidneys.

The potential health impact of PFAAs is unclear. Unlike chlorinated hydrocarbons, PFAAs are not lipophilic (stored in fat), nor genotoxic (damaging genes). Both PFOA and PFOS in high doses cause cancer and the death of newborns in rodents. However, studies on humans have not been able to prove an impact at current exposures. Bottlenose dolphins have some of the highest PFOS concentrations of any wildlife studied; one study suggests an impact on their immune systems.

The biochemical causes of toxicity are also unclear and may differ by molecule, health effect, and even animal. Significant research has been done looking at PPAR-alpha (a protein that interacts with PFAAs and is commonly implicated in contaminant-caused rodent cancers.

Less fluorinated chemicals (not perfluorinated compounds) are also detectable in the environment. Because biological systems do not metabolize fluorinated molecules easily, fluorinated pharmaceuticals (often antibiotics and antidepressants) are among the major fluorinated organics found in treated city sewage and wastewater. Fluorine-containing agrichemicals are measurable in farmland runoff and nearby rivers.

Pharmaceuticals
About 20% of modern pharmaceuticals contain fluorine, including commercially significant drugs in many different pharmaceutical classes. One of these, the cholesterol-reducer atorvastatin (Lipitor), was the number one money-making drug for nearly a decade. The branded asthma medication Serevent (Advair), a top-ten revenue drug as of the mid-2000s, also contains a fluorinated molecule: fluticasone.

Even a single atom of fluorine, added to a drug molecule, can greatly change its chemical properties and thus how it interacts with the body. Because of the considerable stability of the carbon-fluorine bond, many drugs are fluorinated to delay their metabolism and elimination by the body. This allows longer times between doses. Also, adding fluorine to organics increases their lipophilicity (ability to dissolve in fats) because the carbon–fluorine bond is even more hydrophobic than the carbon–hydrogen bond. This effect often increases a drug's bioavailability because of increased cell membrane penetration.



Many modern antidepressants are fluorinated molecules that selectively limit the body's binding of serotonin (low serotonin availability in brain cells is a cause of depression). Prior to the 1980s, traditional antidepressants, such as the tricyclics, altered not only serotonin uptake but also affected several other neurotransmitters. This non-selective interaction caused many side effects. One of the first drugs to alter only serotonin uptake—and be free of most side effects of previous drugs—was fluorine-containing Prozac (fluoxetine). It became the best-selling antidepressant and prompted the popular book Listening to Prozac. Some other selective serotonin reuptake inhibitor (SSRI) antidepressants that are fluorinated are Celexa (and its isomer Lexapro), Luvox, and Paxil.

Quinolones are artificial compounds that are broad-spectrum antibiotics. Most of the currently used quinolones are fluorinated to make the drugs more powerful. Prominent examples include ciprofloxacin (Cipro) and levofloxacin (Levaquin). The latter was the highest selling U.S. antibiotic in 2010.

Fluorine also finds use in many steroidal drugs. Florinef (fludrocortisone) is a mineralocorticoid (a compound used to retain sodium and water and thus raise blood pressure). Kenalog (triamcinolone) and dexamethasone are potent glucocorticoids (anti-inflammatories).

Several inhaled anesthetics, including the most common ones, are heavily fluorinated. The first fluorinated anesthetic, halothane, proved to be much safer (neither explosive nor flammable) and longer-lasting than those previously used. Modern fluorinated anesthetics are longer-lasting still and almost insoluble in blood, which accelerates the awakening. Examples include sevoflurane, desflurane, enflurane, and isoflurane, all fluorinated ethers.

Other biological aspects
An estimated 30% of agrichemical compounds contain fluorine. Most of them are herbicides and fungicides, but a few regulate crop growth. Fluorine substitution (usually of just a single atom or at most a trifluoromethyl group) is a powerful tool for new molecule design. The molecular effects—increasing biological stay time, membrane crossing, altering molecular recognition—are similar to fluorinated pharmaceuticals. Trifluralin is a prominent example, used widely in the United States as a weedkiller. However, its suspected carcinogenic properties have caused many European countries to ban it.



Sodium monofluoroacetate (brand name 1080) is a powerful commercial mammalian poison. The molecule, similar to vinegar but with a hydrogen changed out for fluorine, was first synthesized in the late 19th century. 1080 was recognized as an insecticide in the early 20th century. Later, it was widely used to control mammalian pests (e.g. rats). 1080 is now banned in the European community and the United States, but it is still used in Australia and some other countries. Fluoroacetate deprives cells of energy by replacing acetate in the Krebs cycle, halting a key part of cell metabolism. Several insecticides contain sodium fluoride, which is much less toxic than fluoroacetate.

Artificial blood and liquid breathing research make use of perfluorocarbons (PFCs) because they can hold more oxygen or carbon dioxide than blood does. A blood substitute, Oxycyte, has been through initial clinical trials. PFCs have the potential to aid endurance athletes and are therefore banned from sports; the near death of cyclist Mauro Gianetti was investigated because PFC use was suspected. A liquid breathing effort (but with only partial filling of the lungs) by Alliance Pharmaceuticals reached clinical trials but was abandoned. Several fictional treatments of PFC breathing exist; the 1989 film The Abyss faked deep sea divers breathing PFC but showed a real rat surviving 30 minutes immersion.

3. fluorine dating

Because groundwater contains fluorine ions, organic items such as bone that are buried in soil will absorb those ions over time. As such, it is possible to determine the relative age of an object by comparing the amount of fluoride with another object found in the same area. It is important as a separation technique in intra-site chronological analysis and inter-site comparisons.

However, if no actual age of any object is known, the ages can only be expressed in terms of one of the objects being older or younger than the other. The fluctuating amount of fluoride found in groundwater means the objects being compared must be in the same local area in order for the comparisons to be accurate. This technique is not always reliable, given that not all objects absorb fluoride at the same rates.

To do list
1. pharma rewrite, below.

2. fact check all

3. source the orgo content (research it to allow this)

4. fluorine piping picture (donation)

5. tweak the two new F bonding graphics.

6. archive all website content (books and journals, no need). Make a list. Get Sunny to help.

7. Dashes (get a bot to run).

8. Dabs. (bot)

9. final copyedit for style. (Prune some where possible).

10. Grammar check copyedit.

11. Link checks:
 * all needed
 * going to right article
 * avoid redirects
 * first place used (do MS word or run Ucabot to check).
 * cut second uses

12. Learn, and then check and fix all ref format.

13. Commission Wiki peer review.

14. Commission external peer review. (maybe one of the video guys or the German from donation request).

pharma references
(cut and paste from user talk page)

Bold for already in article

italics for obtained

There is a brief description of the use of fluorine in pharmaceuticals in Organofluorine#Biological_role, which might be a place to start. I did a quick literature search and found several general review articles. I don't know how easy it will be to find any of these, but if you don't have access to any of them through your library, just let me know and I'll see if I can get them. -- Ed (Edgar181) 13:02, 3 January 2012 (UTC)

'''*Hagmann, William K. The Many Roles for Fluorine in Medicinal Chemistry. Journal of Medicinal Chemistry (2008), 51(15), 4359-4369''' '''*Filler, Robert; Saha, Rituparna. Fluorine in medicinal chemistry: a century of progress and a 60-year retrospective of selected highlights. Future Medicinal Chemistry (2009), 1(5), 777-791.'''
 * Purser, Sophie; Moore, Peter R.; Swallow, Steve; Gouverneur, Veronique. Fluorine in medicinal chemistry. Chemical Society Reviews (2008), 37(2), 320-330.
 * Yamazaki, Takashi; Taguchi, Takeo; Ojima, Iwao. Unique properties of fluorine and their relevance to medicinal chemistry and chemical biology. Fluorine in Medicinal Chemistry and Chemical Biology (2009), 3-46.
 * Pattan, S. R.; Dighe, N. S.; Shinde, H. V.; Hole, M. B.; Gaware, V. M. Significance of fluorine in medicinal chemistry: a review. Asian Journal of Research in Chemistry (2009), 2(4), 376-379.
 * Shah, Poonam; Westwell, Andrew D. The role of fluorine in medicinal chemistry. Journal of Enzyme Inhibition and Medicinal Chemistry (2007), 22(5), 527-540.
 * Boehm, Hans-Joachim; Banner, David; Bendels, Stefanie; Kansy, Manfred; Kuhn, Bernd; Mueller, Klaus; Obst-Sander, Ulrike; Stahl, Martin. Fluorine in medicinal chemistry. ChemBioChem (2004), 5(5), 637-643.

Drugs and agrichemicals


Several important pharmacueticals contain fluorine. Of drugs that have been commercialized in the past 50 years, 5–15% contain fluorine, and the percentage of currently available fluorine-containing drugs is increasing.

(add importance examples. resolve issues with amounts)  th 2008 sales of US$12.4 billion, Lipitor was the top-selling branded pharmaceutical in the world. (text from other article).

Because of the considerable stability of the carbon-fluorine bond, many drugs are fluorinated to prevent their metabolism and prolong their half-lives, allowing for longer times between dosing and activation. For example, an aromatic ring may add to prevent the metabolism of a drug, but this presents a safety problem, because enzymes in the body metabolize some aromatic compounds into poisonous epoxides. Substituting a fluorine into a para position, however, protects the aromatic ring and prevents the epoxide from being produced. For instance, Diflunisal has two fluorines on one of its rings and has a half-life of 13 hours. This is much much longer than most other non-steroidal anti-inflammatory drugs and allows doses at 12 hour intervals. Since the carbon–fluorine bond is strong, organofluorides are generally very stable, although the potential of the fluorine to be released as a fluoride leaving group is heavily dependent on its position in the molecule.

Adding fluorine to biologically active organics increases their lipophilicity, because the carbon–fluorine bond is even more hydrophobic than the carbon–hydrogen bond. This effect often increases a drug's bioavailability due to increased cell membrane penetration. (blood brain barriar and tranquilizers.) (Mention trifluoromethyl group.)

For example, fludrocortisone is one of the most common mineralocorticoids, a class of drugs that mimics the actions of aldosterone. The anti-inflammatories dexamethasone and triamcinolone, which are among the most potent of the synthetic corticosteroids class of drugs, contain fluorine. (mineralcorticoid is a subset of corticosteroid, which are steroids made in the adrenal cortex, mineral ones affect salt balance. Other one is gluco, need to straighten out this section.)

Many SSRI antidepressants are fluorinated organics, including citalopram, escitalopram, fluoxetine, fluvoxamine, and paroxetine. (give a little the explanation of what an SSRI is)

Fluoroquinolones are a commonly used family of broad-spectrum antibiotics. (Give some explanation of hospital use, drug-resistant bacteria, when others fail. Modification of quinolones, most now fluoro.)

(make a para on aenesthetics, fire issue, market prevalence, trends, timing) Several inhaled general anesthetic agents, including the most commonly used inhaled agents, also contain fluorine. Examples include sevoflurane, desflurane, and isoflurane, which are hydrofluorocarbon derivatives.

In addition to pharmaceuticals, an estimated 30% of agrochemical compounds contain fluorine.

Because biological systems do not metabolize fluorinated molecules easily, fluorinated pharmaceuticals (often antibiotics and antidepressants) are among the major fluorinated organics found in treated city sewage and wastewater. Because of these, water from agricultural sites contaminates rivers with runoff organofluorines.

ORG (figure out combinations):
 * 1) pharma prevalence and increase
 * 2) ring stability
 * 3) lipophilicity
 * 4) notable classes and members (is there a linkage of rationale and class?)
 * 5) aenesthetics and rationale
 * 6) agrichemicals (prevalence, rationale, cost issue, examples)
 * 7) (all) stability in environment and detection