S-Allyl-L-cysteine

As a flavor ingredient

Identification Description: White powder; cooked roasted brown aroma.

Regulatory Status:
CoE: n/a
FDA: n/a
FDA (other): n/a
JECFA: ADI: Acceptable. No safety concern at current levels of intake when used as a flavoring agent (2007).

Reported uses (ppm): (FEMA, 2007)   Natural occurrence: Reported found in garlic.

Description

L-Deoxyalliin is a water soluble organosulfur compound derived from garlic and is the most abundant constituent of aged garlic extracts. It has neuroprotective and antioxidative activities, reducing edema formation in the ischemic brain by inhibiting free radical-mediated lipid peroxidation and preventing neuronal cell death in cerebral ischemic insult by specifically scavenging peroxynitrite at concentrations up to 100 μM. L-Deoxyalliin also demonstrates various anti-amyloidogenic properties in experimental models of Alzheimer’s disease.

Chemical Properties

White powder; cooked roasted brown aroma.

Occurrence

Reported found in garlic

Uses

antineoplastic

Uses

A water-soluble organosulfur

Uses

L-Deoxyalliin is a organosulfur compound that naturally occurs in garlic. L-Deoxyalliin is known to exhibit neuroprotective and antioxidative properties.

Definition

ChEBI: An S-hydrocarbyl-L-cysteine that is L-cysteine in which the hydrogen attached to the sulphur is replaced by a prop-2-enyl group. It commonly occurs in garlic and has been found to exhibit antineoplastic activity.

Aroma threshold values

High strength odor; recommend smelling in a 0.10% solution or less

General Description

S-Allyl-L-cysteine has anti-inflammatory properties. It inhibits prooxidant enzymes and chelates metals. S-Allyl-L-cysteine exhibits hypoglycemic and cholesterol-lowering effects. It prevents apoptosis, lowers the activity of inducible nitric oxide synthase and blocks nuclear factor kappa B activity.

Biochem/physiol Actions

S-allyl-L-cysteine is a sulfur containing amino acid found in garlic with antioxidant, anti-cancer, antihepatotoxic, neuroprotective and neurotrophic activity. S-allyl-L-cysteine has potent activity in several animal models of ischemic injury and Alzhemer′s disease.

Synthesis

BocSacOMe (9.92 g, 36.02 mmol) was used as raw material and dissolved in CH2Cl2 (100 mL) in a 250 mL round bottom flask. TFA (10 mL) was added to the solution under argon protection and the reaction mixture was stirred at room temperature for 3 hours. The progress of the reaction was monitored by TLC (unfolding agent: 150% EtOAc in petroleum ether solution) to confirm complete consumption of raw materials (Rf = 0.4). Subsequently, the solvent was removed by rotary evaporation and the yellow residue obtained was dried briefly under vacuum. The viscous residue was dissolved in THF (30 mL) and cooled to 0 °C. LiOH (72 mL, 5M aqueous solution) was added to the stirred solution. The ice bath was removed and the reaction mixture continued to stir for 1 h at room temperature. Upon completion of the reaction, it was diluted with 100 mL of H2O and neutralized to pH < 7 (detected by pH paper) using DOWEX(R) resin. All resin was transferred to an empty column, washed with 500 mL H2O (gravity flow), and the effluent was discarded. The product was eluted with 5% NH4OH aqueous solution and washed with 50% H2O (eluent). The grades containing (R)-3-(allylthio)-2-aminopropionic acid (Rf = 0.6) were collected and concentrated by rotary evaporation to give a yellow solid. Further purification by column chromatography [eluent ratio: 7:2:1 iPrOH:MeOH:NH4OH (25% aqueous solution)] afforded white crystals of Sac (3.29 g, 57%). Melting point: 212-213 °C. 1H NMR (400 MHz, D2O): δH = 2.5-2.70 (2H, ABX system, J = 13.3, 5.3, 6.7 Hz, CH2SAllyl), 3.06 (2H, d, J = 7.2 Hz, CH2CH=CH2), 3.28 (1H, dd, J = 6.7, 5.3 Hz , Hα), 5.02-5.09 (2H, m, HC=CH2), 5.71 (1H, m, HC=CH2).

References

[1] Journal of the American Chemical Society, 2008, vol. 130, # 30, p. 9642 - 9643
[2] Patent: US2012/178913, 2012, A1. Location in patent: Page/Page column 10-11