Allicin

Last updated
Allicin
R-allicin-2D-skeletal.svg
R-allicin-3D-balls.png
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. [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. I 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]

In a small clinical trial, a daily high dose of extracted allicin (20 times the amount in a garlic clove) showed effectiveness to prevent the common cold. [14] A Cochrane review found this to be insufficient to draw conclusions. [15]

A study from 2021 has shown "a combination of the short half-life, high reactivity and non-specificity to particular proteins are reasons most bacteria cannot deal with allicin’s mode of action and develop effective defence mechanism" and argue "that could be the key to sustainable drug design addressing serious problems with escalating emergence of multidrug-resistant bacterial strains". [16]

History

It was first isolated and studied in the laboratory by Chester J. Cavallito and John Hays Bailey in 1944. [17] [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. [18] : 302 

See also

Related Research Articles

<span class="mw-page-title-main">Garlic</span> Species of edible plant

Garlic is a species of bulbous flowering plant in the genus Allium. Its close relatives include the onion, shallot, leek, chive, Welsh onion, and Chinese onion. It is native to South Asia, Central Asia and northeastern Iran and has long been used as a seasoning worldwide, with a history of several thousand years of human consumption and use. It was known to ancient Egyptians and has been used as both a food flavoring and a traditional medicine. China produces 76% of the world's supply of garlic.

<span class="mw-page-title-main">Allyl group</span> Chemical group (–CH₂–CH=CH₂)

In organic chemistry, an allyl group is a substituent with the structural formula −CH2−HC=CH2. It consists of a methylene bridge attached to a vinyl group. The name is derived from the scientific name for garlic, Allium sativum. In 1844, Theodor Wertheim isolated an allyl derivative from garlic oil and named it "Schwefelallyl". The term allyl applies to many compounds related to H2C=CH−CH2, some of which are of practical or of everyday importance, for example, allyl chloride.

<span class="mw-page-title-main">Allyl isothiocyanate</span> Chemical compound

Allyl isothiocyanate (AITC) is an organosulfur compound (formula CH2CHCH2NCS). The colorless oil is responsible for the pungent taste of mustard, radish, horseradish, and wasabi. This pungency and the lachrymatory effect of AITC are mediated through the TRPA1 and TRPV1 ion channels. It is slightly soluble in water, but more soluble in most organic solvents.

<span class="mw-page-title-main">Ajoene</span> Chemical compound

Ajoene is an organosulfur compound found in garlic (Allium sativum) extracts. It is a colorless liquid that contains sulfoxide and disulfide functional groups. The name (and pronunciation) is derived from "ajo", the Spanish word for garlic. It is found as a mixture of up to four stereoisomers, which differ in terms of the stereochemistry of the central alkene (E- vs Z-) and the chirality of the sulfoxide sulfur (R- vs S-).

<span class="mw-page-title-main">Alliin</span> Chemical compound

Alliin is a sulfoxide that is a natural constituent of fresh garlic. It is a derivative of the amino acid cysteine. When fresh garlic is chopped or crushed, the enzyme alliinase converts alliin into allicin, which is responsible for the aroma of fresh garlic. Allicin and other thiosulfinates in garlic are unstable and form a number of other compounds, such as diallyl sulfide (DAS), diallyl disulfide (DADS) and diallyl trisulfide (DAT), dithiins and ajoene. Garlic powder is not a source of alliin, nor is fresh garlic upon maceration, since the enzymatic conversion to allicin takes place in the order of seconds.

<span class="mw-page-title-main">Diallyl disulfide</span> Chemical compound

Diallyl disulfide is an organosulfur compound derived from garlic and a few other genus Allium plants. Along with diallyl trisulfide and diallyl tetrasulfide, it is one of the principal components of the distilled oil of garlic. It is a yellowish liquid which is insoluble in water and has a strong garlic odor. It is produced during the decomposition of allicin, which is released upon crushing garlic and other plants of the family Alliaceae. Diallyl disulfide has many of the health benefits of garlic, but it is also an allergen causing garlic allergy. Highly diluted, it is used as a flavoring in food. It decomposes in the human body into other compounds such as allyl methyl sulfide.

<i>S</i>-Allylcysteine Chemical compound

S-Allylcysteine (SAC) is an organosulfur compound that has the formula HO2CCH(NH2)CH2SCH2C=CH2. It is the S-allylated derivative of the amino acid cysteine. As such only the L-enantiomer is significant biologically. SAC constituent of aged garlic. A number of related compounds are found in garlic, including the disulfide S-"allylmercaptocysteine" and γ-glutamyl-S-allylcysteine" (GSAC).

<span class="mw-page-title-main">Stainless steel soap</span> Piece of stainless steel

Stainless steel soap is a piece of stainless steel, in the form of a soap bar or other hand-held shape. Its purported purpose is to neutralize or reduce strong odors such as those from handling garlic, onion, durian, guava, salami, or fish.

<span class="mw-page-title-main">Sulfenic acid</span> Organosulfur compound of the form R–SOH

In chemistry, a sulfenic acid is an organosulfur compound and oxoacid with the general formula R−S−OH. It is the first member of the family of organosulfur oxoacids, which also include sulfinic acids and sulfonic acids, respectively. The base member of the sulfenic acid series with R = H is hydrogen thioperoxide.

<i>syn</i>-Propanethial-<i>S</i>-oxide Chemical compound

syn-Propanethial S-oxide (or (Z)-propanethial S-oxide), a member of a class of organosulfur compounds known as thiocarbonyl S-oxides (formerly "sulfines"), is a volatile liquid that acts as a lachrymatory agent (triggers tearing and stinging on contact with the eyes). The chemical is released from onions, Allium cepa, as they are sliced. The release is due to the breaking open of the onion cells and their releasing enzymes called alliinases, which then break down amino acid sulfoxides, generating sulfenic acids. A specific sulfenic acid, 1-propenesulfenic acid, formed when onions are cut, is rapidly rearranged by a second enzyme, called the lachrymatory factor synthase or LFS, giving syn-propanethial S-oxide. The gas diffuses through the air and, on contact with the eye, it stimulates sensory neurons creating a stinging, painful sensation. Tears are released from the tear glands to dilute and flush out the irritant. A structurally related lachrymatory compound, syn-butanethial S-oxide, C4H8OS, has been found in another genus Allium plant, Allium siculum.

<span class="mw-page-title-main">Alliinase</span> Class of enzyme

In enzymology, an alliin lyase is an enzyme that catalyzes the chemical reaction

<span class="mw-page-title-main">Allithiamine</span> Chemical compound

Allithiamine (thiamine allyl disulfide or TAD) is a lipid-soluble form of vitamin B1 which was discovered in garlic (Allium sativum) in the 1950s along with its homolog prosultiamine. They were both investigated for their ability to treat Wernicke–Korsakoff syndrome and beriberi better than thiamine.

Allyl methyl sulfide is an organosulfur compound with the chemical formula CH2=CHCH2SCH3. The molecule features two functional groups, an allyl (CH2=CHCH2) and a sulfide. It is a colourless liquid with a strong odor characteristic of alkyl sulfides. It is a metabolite of garlic, and "garlic breath" is attributed to its presence.

<span class="mw-page-title-main">Thiosulfinate</span> Functional group

In organosulfur chemistry, thiosulfinate is a functional group consisting of the linkage R-S(O)-S-R. Thiolsulfinates are also named as alkanethiosulfinic acid esters.

<span class="mw-page-title-main">Garlic allergy</span> Type of skin allergy caused by garlic

Garlic allergy or allergic contact dermatitis to garlic is a common inflammatory skin condition caused by contact with garlic oil or dust. It mostly affects people who cut and handle fresh garlic, such as chefs, and presents on the tips of the thumb, index and middle fingers of the non-dominant hand. The affected fingertips show an asymmetrical pattern of fissure as well as thickening and shedding of the outer skin layers, which may progress to second- or third-degree burn of injured skin.

Vinyldithiins, more precisely named 3-vinyl-4H-1,2-dithiin and 2-vinyl-4H-1,3-dithiin, are organosulfur phytochemicals formed in the breakdown of allicin from crushed garlic (Allium sativum). Vinyldithiins are Diels-Alder dimers of thioacrolein, H2C=CHCH=S, formed in turn by decomposition of allicin. In garlic supplements, vinyldithiins are only found in garlic oil macerates that are made by incubation of crushed garlic in oil.

<span class="mw-page-title-main">Garlic breath</span> Bad breath induced by the consumption of garlic

Garlic breath is halitosis resulting from the consumption of garlic.

Chester J. Cavallito was an American organic chemist. He was particularly known for his work on the chemistry of garlic. Beginning in 1944, with his colleagues, he reported on the isolation from crushed garlic, synthesis and antibiotic activity of a compound he named allicin. Cavallito established that allicin was a member of a class of organosulfur compounds known as thiosulfinates. He also synthesized and reported on the chemical and biological properties of a series of thiosulfinates related to allicin.

<span class="mw-page-title-main">Laba garlic</span> Vinegar-preserved garlic of Chinese tradition

The Laba garlic is a vinegar-preserved garlic. Its refined color is green or blue and its taste is sour and slightly spicy. Because it is usually made in the 8th day of the 12th month of the Chinese Lunar calendar, the Laba Festival, it was named Laba garlic. In general, green and vinegary garlic is called Laba garlic.

Diallyl trisulfide (DATS), also known as Allitridin, is an organosulfur compound with the formula S(SCH2CH=CH2)2. It is one of several produced by the hydrolysis of allicin, including diallyl disulfide and diallyl tetrasulfide; DATS is one of the most potent.

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. doi:10.1021/jf60174a007.
  11. ↑ Yu T, Wu C (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. ↑ Nahas R, Balla A (January 2011). "Complementary and alternative medicine for prevention and treatment of the common cold". Canadian Family Physician. 57 (1): 31–6. PMC   3024156 . PMID   21322286.
  15. ↑ 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.
  16. ↑ Janská P, Knejzlík Z, Perumal AS, Jurok R, Tokárová V, Nicolau DV, et al. (2021-03-19). "Effect of physicochemical parameters on the stability and activity of garlic alliinase and its use for in-situ allicin synthesis". PLOS ONE. 16 (3): e0248878. Bibcode:2021PLoSO..1648878J. doi: 10.1371/journal.pone.0248878 . PMC   7978267 . PMID   33740023.
  17. ↑ 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. doi:10.1021/ja01239a048.
  18. ↑ 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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