Phosphatidylcholine

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1-Oleoyl-2-palmitoyl-phosphatidylcholine

Phosphatidylcholines (PC) are a class of phospholipids that incorporate choline as a headgroup. They are a major component of

soybeans, from which they are mechanically or chemically extracted using hexane. They are also a member of the lecithin group of yellow-brownish fatty substances occurring in animal and plant tissues. Dipalmitoylphosphatidylcholine (lecithin) is a major component of the pulmonary surfactant, and is often used in the lecithin–sphingomyelin ratio to calculate fetal lung maturity. While phosphatidylcholines are found in all plant and animal cells, they are absent in the membranes of most bacteria,[1] including Escherichia coli.[2] Purified phosphatidylcholine is produced commercially.[citation needed
]

The name lecithin was derived from

Theodore Nicolas Gobley, a French chemist and pharmacist of the mid-19th century, who applied it to the egg yolk phosphatidylcholine that he identified in 1847. Gobley eventually completely described his lecithin from chemical structural point of view, in 1874. Phosphatidylcholines are such a major component of lecithin that in some contexts the terms are sometimes used as synonyms. However, lecithin extracts consist of a mixture of phosphatidylcholine and other compounds. It is also used along with sodium taurocholate for simulating fed- and fasted-state biorelevant media in dissolution studies of highly lipophilic
drugs.

Phosphatidylcholine is a major constituent of cell membranes and pulmonary surfactant, and is more commonly found in the exoplasmic or outer leaflet of a cell membrane. It is thought to be transported between membranes within the cell by phosphatidylcholine transfer protein (PCTP).[3]

Phosphatidylcholine also plays a role in membrane-mediated cell signaling and PCTP activation of other enzymes.[4]

Structure and physical properties

Palmitoyl-oleyl-sn-phosphatidylcholine, a phosphatidylcholine

This phospholipid is composed of a choline head group and glycerophosphoric acid, with a variety of fatty acids. Usually, one is a

unsaturated fatty acid (here oleic acid, or 9Z-octadecenoic acid, as in Gobley's original egg yolk lecithin). However, there are also examples of disaturated species. Animal lung phosphatidylcholine, for example, contains a high proportion of dipalmitoylphosphatidylcholine.[5]

phosphatidic acid (PA), releasing the soluble choline headgroup into the cytosol.[citation needed
]

Possible health benefits

Senescence

A 2009

clinical trials in humans found that there was not enough evidence to support supplementation of lecithin or phosphatidylcholine in dementia. The study found that a moderate benefit could not be ruled out until further large scale studies were performed.[6]

Lipolysis

Though phosphatidylcholine has been studied as an alternative to

lipomas has been studied, but the results have been mixed.[9][10]

Ulcerative colitis

Treatment of ulcerative colitis with oral intake of phosphatidylcholine has been shown to result in decreased disease activity.[11]

Biosynthesis

Although multiple pathways exist for the biosynthesis of phosphatidylcholine, the predominant route in eukaryotes involves condensation between diacylglycerol (DAG) and cytidine 5'-diphosphocholine (CDP-choline or citicoline). The conversion is mediated by the enzyme diacylglycerol cholinephosphotransferase. Another pathway, mainly operative in the liver involves methylation of phosphatidylethanolamine with S-adenosyl methionine (SAM) being the methyl group donor.[12]

Additional images

  • General structural formula of phosphatidylcholines
    General structural formula of phosphatidylcholines
  • Membrane lipids
    Membrane lipids
  • Choline metabolism
    Choline metabolism
  • Phosphatidate
    Phosphatidate
  • Choline
    Choline

See also

References

  1. ISBN 978-0-444-89321-5
    .
  2. PMID 19940943
    .
  3. PMID 1883207
    .
  4. PMID 17704541
    .
  5. ^ Christie WW. "Phosphatidylcholine and Related Lipids: Structure, Occurrence, Biochemistry and Analysis". Invergowrie, Dundee (DD2 5DA), Scotland.: James Hutton Institute. Archived from the original on 2014-12-11. Retrieved 2012-08-06.{{cite web}}: CS1 maint: location (link)
  6. PMID 12917896
    .
  7. S2CID 9994696
    . Recent laboratory investigations17 demonstrate that sodium deoxycholate, a bile salt also used as a laboratory detergent,102,103 was just as potent at causing adipocyte lysis and cell death as the complete phosphatidylcholine formula, which contains both phosphatidylcholine and deoxycholate (Figure 3). This bile salt is used to solubilize phosphatidylcholine by forming mixed micelles composed of phosphatidylcholine and deoxycholate.102,104 It is common practice to combine intravenous medications with bile salts to improve their water solubility.105,106 These findings suggest that sodium deoxycholate is the primary active ingredient in the phosphatidylchloline preparations.
  8. S2CID 22619355
    . The author, when discussing phosphatidylcholine as a part of mesotherapy concludes: 'Although there is a preliminary report contradictory to this result, there was no body contouring observed in this study. There were no statistically significant changes in thigh girth, cross-sectional area, or laboratory values for the lipid profile except for a decrease in the triglyceride level in the blood, which might be an indirect effect of the method of aminophylline absorption into the systemic circulation.'
  9. PMID 25013540
    .
  10. PMID 21976907
    .
  11. S2CID 4074211
    .
  12. OCLC 940961458.{{cite book}}: CS1 maint: location missing publisher (link
    )

External links