Allicin

Allicin
Names
Preferred IUPAC name
2-Propene-1-sulfinothioic acid S-2-propenyl ester
Systematic IUPAC name
3-[(Prop-2-ene-1-sulfinyl)sulfanyl]prop-1-ene
Identifiers
539-86-6 N
1752823
ChEBI CHEBI:28411 YesY
ChEMBL ChEMBL359965 YesY
ChemSpider 58548 YesY
EC Number 208-727-7
2419
Jmol interactive 3D Image
Image
KEGG C07600 YesY
MeSH Allicin
PubChem 65036
UNII 3C39BY17Y6 YesY
Properties
C6H10OS2
Molar mass 162.26 g·mol−1
Appearance Colourless liquid
Density 1.112 g cm−3
Melting point <25 °C
Boiling point decomposes
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YesYN ?)
Infobox references

Allicin is an organosulfur compound obtained from garlic, a species in the family Alliaceae.[1] It was first isolated and studied in the laboratory by Chester J. Cavallito and John Hays Bailey in 1944.[2][3] When fresh garlic is chopped or crushed, the enzyme alliinase converts alliin into allicin, which is responsible for the aroma of fresh garlic.[4] The allicin generated is very unstable and quickly changes into a series of other sulfur-containing compounds such as diallyl disulfide.[5] It is under preliminary research for its potential to have antibacterial, antifungal, antiviral or antiprotozoal activity.[6] Allicin is garlic's defense mechanism against attacks by pests.[7]

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.[3] The racemic form can also be generated by oxidation of diallyl disulfide:[8]

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

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.[9][10] Furthermore, allicin can be unstable, breaking down within 16 h at 23 °C.[11]

Biosynthesis of Allicin

Allicin is an oily, slightly yellow liquid that gives garlic its unique odor. It is a thioester of sulfenic acid and is also known as allyl thiosulfinate.[12] Its biological activity can be attributed to both its antioxidant activity and its reaction with thiol containing proteins.[13]

In the biosynthesis of allicin (thio-2-propene-1-sulfinic acid S-allyl ester), cysteine is first converted into alliin (+ S-allyl-L-cysteine sulfoxide). The enzyme alliinase, which contains pyridoxal phosphate (PLP), cleaves alliin, generating allysulfenic acid, pyruvate, and ammonium.[13] At room temperature allysulfenic acid is unstable and highly reactive, which cause two molecules of it to spontaneously combine in a dehydration reaction to form allicin.[12]

Allicin is produced in garlic cells when they are damaged, which is why garlic’s scent is most potent once it is being cut or cooked. It is believed that alliin and alliinase are kept in separate compartments of the cells and can only combine once these compartments have been ruptured.[14]

Biosynthesis of Allicin

Potential health benefits

Several animal studies published between 1995 and 2005 indicate that allicin may reduce atherosclerosis and fat deposition,[15][16] normalize the lipoprotein balance, decrease blood pressure,[17][18] have anti-thrombotic[19] and anti-inflammatory activities, and function as an antioxidant to some extent.[20][21][22] Other animal studies have shown a strong oxidative effect in the gut that can damage intestinal cells, though many of these results were obtained by excessive amounts of allicin, which has been clearly shown to have some toxicity at high amounts, or by physically injecting the lumen itself with allicin, which may not be indicative of what would happen via oral ingestion of allicin or garlic supplements.[23][24] A randomized clinical trial found that the consumption of garlic in any form did not reduce blood cholesterol levels in patients with moderately high baseline cholesterol levels.[25] The fresh garlic used in this study contained substantial levels of allicin, so the study casts doubt on the ability of allicin when taken orally to reduce blood cholesterol levels in human subjects.

Antibacterial activity

In laboratory studies, allicin has been found to have numerous antimicrobial properties, and has been studied in relation to both its effects and its biochemical interactions.[26] One potential application is in the treatment of methicillin-resistant Staphylococcus aureus (MRSA), an increasingly prevalent concern in hospitals. A screening of allicin against 30 strains of MRSA found antimicrobial activity, including against strains resistant to other chemical agents.[27]

Antiviral activity

Allicin is under preliminary research for its potential antiviral activity. Among viruses being investigated are Herpes simplex type 1 and 2, Parainfluenza virus type 3, human Cytomegalovirus, Influenza B, Vaccinia virus, Vesicular stomatitis virus and Human rhinovirus type 2.[28]

See also

Wikimedia Commons has media related to allicin.

References

  1. 1 2 3 Eric Block (1985). "The chemistry of garlic and onions". Scientific American 252 (March): 114–9. doi:10.1038/scientificamerican0385-114. PMID 3975593.
  2. ↑ Cavallito, Chester J.; Bailey, John Hays (1944). "Allicin, the Antibacterial Principle of Allium sativum. I. Isolation, Physical Properties and Antibacterial Action". Journal of the American Chemical Society 66 (11): 1950. doi:10.1021/ja01239a048.
  3. 1 2 Eric Block (2010). Garlic and Other Alliums: The Lore and the Science. Cambridge: Royal Society of Chemistry.
  4. ↑ Kourounakis, PN; Rekka, EA (November 1991). "Effect on active oxygen species of alliin and Allium sativum (garlic) powder". Res Commun Chem Pathol Pharmacol. 74 (2): 249–252. PMID 1667340.
  5. ↑ Ilic, Dusica; Nikolic, Vesna; Nikolic, Ljubisa; Stankovic, Mihajlo; Stanojevic, Ljiljana; Cakic, Milorad (2011). "Allicin and related compounds: Biosynthesis, synthesis and pharmacological activity" (PDF). Facta Universitatis 9 (1): 9–20. doi:10.2298/FUPCT1101009I.
  6. ↑ Salama, A. A.; Aboulaila, M; Terkawi, M. A.; Mousa, A; El-Sify, A; Allaam, M; Zaghawa, A; Yokoyama, N; Igarashi, I (2014). "Inhibitory effect of allicin on the growth of Babesia and Theileria equi parasites". Parasitology Research 113 (1): 275–83. doi:10.1007/s00436-013-3654-2. PMID 24173810.
  7. ↑ What is Allicin?. Phytochemicals.info. Retrieved on 2012-12-26.
  8. ↑ Cremlyn, R. J. W. (1996). An introduction to organosulfur chemistry. Wiley. ISBN 0-471-95512-4.
  9. ↑ Brodnitz, M.H., Pascale, J.V., Derslice, L.V. (1971). "Flavor components of garlic extract". Journal of Agricultural and Food Chemistry 19 (2): 273–5. doi:10.1021/jf60174a007.
  10. ↑ Yu, Tung-HSI; Wu, Chung-MAY (1989). "Stability of Allicin in Garlic Juice". Journal of Food Science 54 (4): 977. doi:10.1111/j.1365-2621.1989.tb07926.x.
  11. ↑ 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 0-683-18147-5.
  12. 1 2 Nikolic, V; Stankovic, M; Nikolic, Lj; Cvetkovic, D (Jan 2004). "Mechanism and kinetics of synthesis of allicin". Pharmazie 59 (1): 10–4. PMID 14964414.
  13. 1 2 Rabinkov, A; Miron, T; Konstantinovski, L; Wilchek, M; Mirelman, D; Weiner, L (Feb 1998). "The mode of action of allicin: trapping of radicals and interaction with thiol containing proteins". Biochim Biophys Acta 1379 (2): 233–44. doi:10.1016/s0304-4165(97)00104-9. PMID 9528659.
  14. ↑ Focke, M; Feld, A; Lichtenthaler, K (Feb 1990). "Allicin, a naturally occurring antibiotic from garlic, specifically inhibits acetyl-CoA synthetase". FEBS Lett 261 (1): 106–8. doi:10.1016/0014-5793(90)80647-2. PMID 1968399.
  15. ↑ S. Eilat, Y. Oestraicher, A. Rabinkov, D. Ohad, D. Mirelman, A. Battler, M. Eldar and Z. Vered (1995). "Alteration of lipid profile in hyperlipidemic rabbits by allicin, an active constituent of garlic". Coron. Artery Dis. 6 (12): 985–990. PMID 8723021.
  16. ↑ D. Abramovitz, S. Gavri, D. Harats, H. Levkovitz, D. Mirelman, T. Miron, S. Eilat-Adar, A. Rabinkov, M. Wilchek, M. Eldar and Z. Vered, (1999). "Allicin-induced decrease in formation of fatty streaks (atherosclerosis) in mice fed a cholesterol-rich diet". Coron. Artery Dis. 10 (7): 515–9. doi:10.1097/00019501-199910000-00012. PMID 10562920.
  17. ↑ Silagy CA, Neil HA (1994). "A meta-analysis of the effect of garlic on blood pressure". J Hypertens 12 (4): 463–8. doi:10.1097/00004872-199404000-00017. PMID 8064171.
  18. ↑ A. Elkayam, D. Mirelman, E. Peleg, M. Wilchek, T. Miron, A. Rabinkov, M. Oron-Herman and T. Rosenthal (2003). "The effects of allicin on weight in fructose-induced hyperinsulinemic, hyperlipidemic, hypertensive rats". Am. J. Hypertens. 16 (12): 1053–6. doi:10.1016/j.amjhyper.2003.07.011. PMID 14643581.
  19. ↑ Srivastava KC (1986). "Evidence for the mechanism by which garlic inhibits platelet aggregation". Prostaglandins Leukot Med 22 (3): 313–321. doi:10.1016/0262-1746(86)90142-3. PMID 3088604.
  20. ↑ U. Sela, S. Ganor, I. Hecht, A. Brill, T. Miron, A. Rabinkov, M. Wilchek, D. Mirelman, O. Lider and R. Hershkoviz (2004). "Allicin inhibits SDF-1alpha-induced T cell interactions with fibronectin and endothelial cells by down-regulating cytoskeleton rearrangement, Pyk-2 phosphorylation and VLA-4 expression". Immunology 111 (4): 391–399. doi:10.1111/j.0019-2805.2004.01841.x. PMC 1782446. PMID 15056375.
  21. ↑ Lindsey J. Macpherson, Bernhard H. Geierstanger, Veena Viswanath, Michael Bandell, Samer R. Eid, SunWook Hwang, and Ardem Patapoutian (2005). "The pungency of garlic: Activation of TRPA1 and TRPV1 in response to allicin]". Current Biology 15 (10): 929–934. doi:10.1016/j.cub.2005.04.018. PMID 15916949.
  22. ↑ Bautista DM, Movahed P, Hinman A, Axelsson HE, Sterner O, Hogestatt ED, Julius D, Jordt SE and Zygmunt PM (2005). "Pungent products from garlic activate the sensory ion channel TRPA1". Proceedings of the National Academy of Sciences of the United States of America 102 (34): 12248–52. doi:10.1073/pnas.0505356102. PMC 1189336. PMID 16103371.
  23. ↑ Banerjee, SK; Mukherjee, PK; Maulik, SK (2001). "Garlic as an Antioxidant: The Good, The Bad and The Ugly". Phytotherapy Research 17 (2): 97–106. doi:10.1002/ptr.1281. PMID 12601669.
  24. ↑ Amagase, H; Petesch, BL; Matsuura, H; Kasuga, S; Itakura, Y (2003). "Intake of garlic and its bioactive components". J Nutr 131 (3s): 955S–62S. PMID 11238796.
  25. ↑ Gardner CD, Lawson LD, Block E; et al. (2007). "Effect of raw garlic vs commercial garlic supplements on plasma lipid concentrations in adults with moderate hypercholesterolemia: a randomized clinical trial". Arch. Intern. Med. 167 (4): 346–53. doi:10.1001/archinte.167.4.346. PMID 17325296.
  26. ↑ Ankri, S; Mirelman D (1999). "Antimicrobial properties of allicin from garlic". Microbes Infect 2 (2): 125–9. doi:10.1016/S1286-4579(99)80003-3. PMID 10594976.
  27. ↑ Cutler, RR; P Wilson (2004). "Antibacterial activity of a new, stable, aqueous extract of allicin against methicillan-resistant Staphylococcus aureus" (PDF). British Journal of Biomedical Science 61 (2): 71–4. PMID 15250668.
  28. ↑ Ilić, Dušica; Nikolić, Vesna; Ćirić, Ana; Soković, Marina; Stanojković, Tatjana; Kundaković, Tatjana; Stanković, Mihajlo; Nikolić, Ljubiša (9 January 2012). "Cytotoxicity and antimicrobial activity of allicin and its transformation products". Journal of Medicinal Plants Research 6 (1): 59–65. doi:10.5897/JMPR11.917.

External links

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