Allicin

Last updated
Allicin
Structural formula of R-allicin R-allicin-2D-skeletal.svg
Structural formula of R-allicin
Ball and stick model of R-allicin R-allicin-3D-balls.png
Ball and stick model of R-allicin
Names
Preferred IUPAC name
S-(Prop-2-en-1-yl) prop-2-ene-1-sulfinothioate
Other names
2-Propene-1-sulfinothioic acid S-2-propenyl ester
3-[(Prop-2-ene-1-sulfinyl)sulfanyl]prop-1-ene
S-Allyl prop-2-ene-1-sulfinothioate
Identifiers
3D model (JSmol)
1752823
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.007.935 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 208-727-7
KEGG
MeSH Allicin
PubChem CID
UNII
  • InChI=1S/C6H10OS2/c1-3-5-8-9(7)6-4-2/h3-4H,1-2,5-6H2 Yes check.svgY
    Key: JDLKFOPOAOFWQN-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/C6H10OS2/c1-3-5-8-9(7)6-4-2/h3-4H,1-2,5-6H2
    Key: JDLKFOPOAOFWQN-UHFFFAOYAO
  • O=S(SC\C=C)C\C=C
  • C=CCSS(=O)CC=C
Properties
C6H10OS2
Molar mass 162.26 g·mol−1
AppearanceColourless liquid
Density 1.112 g cm−3
Melting point <25 °C (77 °F; 298 K)
Boiling point decomposes
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

Allicin is an organosulfur compound obtained from garlic and leeks. [1] When fresh garlic is chopped or crushed, the enzyme alliinase converts alliin into allicin, which is responsible for the aroma of fresh garlic. [2] Allicin is unstable and quickly changes into a series of other sulfur-containing compounds such as diallyl disulfide. [3] Allicin is an antifeedant, i.e. the defense mechanism against attacks by pests on the garlic plant. [4]

Contents

Allicin is an oily, slightly yellow liquid that gives garlic its distinctive odor. It is a thioester of sulfenic acid. It is also known as allyl thiosulfinate. [5] Its biological activity can be attributed to both its antioxidant activity and its reaction with thiol-containing proteins. [6]

Structure and occurrence

Allicin features the thiosulfinate functional group, R-S-(O)-S-R. The compound is not present in garlic unless tissue damage occurs, [1] and is formed by the action of the enzyme alliinase on alliin. [1] Allicin is chiral but occurs naturally only as a racemate. [7] The racemic form can also be generated by oxidation of diallyl disulfide: [8] [9]

(SCH2CH=CH2)2 + 2 RCO3H + H2O → 2 CH2=CHCH2SOH + 2 RCO2H
2 CH2=CHCH2SOH → CH2=CHCH2S(O)SCH2CH=CH2 + H2O

Alliinase is irreversibly deactivated below pH 3; as such, allicin is generally not produced in the body from the consumption of fresh or powdered garlic. [10] [11] Furthermore, allicin can be unstable, breaking down within 16 hours at 23 °C. [12]

Biosynthesis

The biosynthesis of allicin commences with the conversion of cysteine into S-allyl-L-cysteine. Oxidation of this thioether gives the sulfoxide (alliin). The enzyme alliinase, which contains pyridoxal phosphate (PLP), cleaves alliin, generating allylsulfenic acid (CH2=CHCH2SOH), pyruvate, and ammonium ions. [6] At room temperature, two molecules of allylsulfenic acid condense to form allicin. [5] [9]

Research

Allicin has been studied for its potential to treat various kinds of multiple drug resistance bacterial infections, as well as viral and fungal infections in vitro, but as of 2016, the safety and efficacy of allicin to treat infections in people was unclear. [13]

A Cochrane review found there to be insufficient clinical evidence regarding the effects of allicin in preventing or treating common cold. [14]

History

It was first isolated and studied in the laboratory by Chester J. Cavallito and John Hays Bailey in 1944. [15] [7] Allicin was discovered as part of efforts to create thiamine derivatives in the 1940s, mainly in Japan. Allicin became a model for medicinal chemistry efforts to create other thiamine disulfides. The results included sulbutiamine, fursultiamine (thiamine tetrahydrofurfuryl disulfide) and benfothiamine. These compounds are hydrophobic, easily pass from the intestines to the bloodstream, and are reduced to thiamine by cysteine or glutathione. [16] : 302 

See also

References

  1. 1 2 3 Block E (March 1985). "The Chemistry of Garlic and Onions". Scientific American. 252 (3): 114–9. Bibcode:1985SciAm.252c.114B. doi:10.1038/scientificamerican0385-114. PMID   3975593.
  2. ↑ Kourounakis PN, Rekka EA (November 1991). "Effect on active oxygen species of alliin and Allium sativum (garlic) powder". Research Communications in Chemical Pathology and Pharmacology. 74 (2): 249–52. PMID   1667340.
  3. ↑ Ilic D, Nikolic V, Nikolic L, Stankovic M, Stanojevic L, Cakic M (2011). "Allicin and related compounds: Biosynthesis, synthesis and pharmacological activity" (PDF). Facta Universitatis. 9 (1): 9–20. doi:10.2298/FUPCT1101009I.
  4. ↑ Borlinghaus J, Albrecht F, Gruhlke MC, Nwachukwu ID, Slusarenko AJ (August 2014). "Allicin: chemistry and biological properties". Molecules. 19 (8): 12591–618. doi: 10.3390/molecules190812591 . PMC   6271412 . PMID   25153873.
  5. 1 2 Nikolic V, Stankovic M, Nikolic L, Cvetkovic D (January 2004). "Mechanism and kinetics of synthesis of allicin". Die Pharmazie. 59 (1): 10–4. PMID   14964414.
  6. 1 2 Rabinkov A, Miron T, Konstantinovski L, Wilchek M, Mirelman D, Weiner L (February 1998). "The mode of action of allicin: trapping of radicals and interaction with thiol containing proteins". Biochimica et Biophysica Acta (BBA) - General Subjects. 1379 (2): 233–44. doi:10.1016/s0304-4165(97)00104-9. PMID   9528659.
  7. 1 2 Block E (2010). Garlic and Other Alliums: The Lore and the Science. Cambridge: Royal Society of Chemistry. ISBN   978-0854041909.
  8. ↑ Cremlyn RJ (1996). An introduction to organosulfur chemistry. Wiley. ISBN   0-471-95512-4.
  9. 1 2 Borlinghaus J, Albrecht F, Gruhlke MC, Nwachukwu ID, Slusarenko AJ (August 2014). "Allicin: chemistry and biological properties". Molecules. 19 (8): 12591–618. doi: 10.3390/molecules190812591 . PMC   6271412 . PMID   25153873.
  10. ↑ Brodnitz MH, Pascale JV, Derslice LV (1971). "Flavor components of garlic extract". Journal of Agricultural and Food Chemistry. 19 (2): 273–5. Bibcode:1971JAFC...19..273B. doi:10.1021/jf60174a007.
  11. ↑ Yu TH, Wu CM (1989). "Stability of Allicin in Garlic Juice". Journal of Food Science. 54 (4): 977. doi:10.1111/j.1365-2621.1989.tb07926.x.
  12. ↑ Hahn G (1996). Koch HP, Lawson LD (eds.). Garlic: the science and therapeutic application of Allium sativum L and related species (2nd ed.). Baltimore: Williams and Wilkins. pp. 1–24. ISBN   978-0-683-18147-0.
  13. ↑ Marchese A, Barbieri R, Sanches-Silva A, Daglia M, Nabavi SF, Jafari NJ, Izadi M, Ajami M, Nabavi SM (2016). "Antifungal and antibacterial activities of allicin: A review". Trends in Food Science and Technology. 52: 49–56. doi:10.1016/j.tifs.2016.03.010.
  14. ↑ Lissiman E, Bhasale AL, Cohen M (November 2014). "Garlic for the common cold". The Cochrane Database of Systematic Reviews. 2020 (11): CD006206. doi:10.1002/14651858.CD006206.pub4. PMC   6465033 . PMID   25386977.{{cite journal}}: CS1 maint: article number as page number (link)
  15. ↑ Cavallito CJ, Bailey JH (1944). "Allicin, the Antibacterial Principle of Allium sativum. I. Isolation, Physical Properties and Antibacterial Action". Journal of the American Chemical Society. 66 (11): 1950. Bibcode:1944JAChS..66.1950C. doi:10.1021/ja01239a048.
  16. ↑ Bettendorff L (2014). "Chapter 7 - Thiamine". In Zempleni J, Suttie JW, Gregory JF, Stover PJ (eds.). Handbook of vitamins (Fifth ed.). Hoboken: CRC Press. pp. 267–324. ISBN   978-1-4665-1557-4.
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