Allyl thiosulfinate

Methyl allyl thiosulfinate (0.3 mg/g) -Allyl trans-l-propenyl thiosulfinate (0.05-1.0mg/g)... 

Sl-propenyl allyl thiosulfinate-ff.Z) + Allyl 1-propenyl thiosulfinate-( ) 19.6... 

Canizares, R, Gracia, I., Gomex, L.A. et al. (2004). Allyl thiosulfinates, the bacteriostatic compounds of garlic against Helicobacter pylori Biotechnol. Prog., 20, 397 01. 

The thermolysis of acyclic- and/or six- and larger ring sulfoxides to yield olefins and sulfenic acids is well documented . The formation of allylic sulfenic acids and thiosulfinates in the thermolysis of thiirane oxides containing hydrogen on the a-carbon of the ring substituent (which is syn to the S—O bond) has been discussed previously in terms of /i-elimination of hydrogen, which is facilitated by relief of strain in the three-membered ring (Section llI.C.l). 

Garlic also contains S-propylcysteine-sulfoxide (PCSO) and S-methylcysteine-sulfoxide (MCSO). PCSO can generate over 50 compounds depending on temperature and water content. The action of allinase on the mixture of alliin, PCSO, and MCSO can produce many other molecules, including allyl methane thiosulfinate, methyl methanethiosulfinate, and other mixed or symmetrical thiosulfinates (R-S-S-R ), where R and R are methyl, propyl, and allyl groups. 

Members of the allium family (onions, garlic, and leeks) contain cysteine sulfoxide derivatives (allyl sulfur compounds), such as allicin and alliin (see Figure 14.9). When the plant cells are damaged, the enzyme alliinase is released from vacuoles and catalyzes the formation of thiosulfinates and thiols, including the lachrymator thiopropanal S-oxide. Their function in the plant is presumably to provide protection against attack by pests. 

Calvey, E.M., Matusik, J.E., White, K.D., DeOrazio, R., Sha, D. and Block, E. (1997) Allium chemistry supercritical fluid extraction and LC-APCI-MS of thiosulfinates and related compounds from homogenates of garlic, onion, and ramp. Identification in garlic and ramp and synthesis of 1-propanesulfinothioic acid S-allyl ester. J. Agric. Food Chem. 45(11) 4405-4413. 

The thiosulfinates (e.g., allicin) arc vray reactive, combining with reducing agents and vmdergoing spontaneous reactiorrs in various solvents and media (Lawson, in Koch and Lawson, 1996, pp. 59-65). The reaction products are more stable than the thiosulfinates but still contain the thioallyl groups (5-allyl) or thiomethyl groups, and are active components in garlic oils. 

At room temperature the thiosulfinates (e.g., allicin) convert to variorrs diallyl and allyl sulfides, etc., which may be accelerated by heating. Pnre allicin itself is an unstable oily liquid, lasting less than 20 hours at room temperature (equivalent to say a half-life of a few hours, as has been reported). The decomposition products include various organic sulfides, and it is also been observed that allicin is very reactive with the amino acid cysteine. 

The transformation products of allicin and odier thiosulfinates present in crushed garlic is greatly accelerated and expanded upon heating such as during steam distillation or cooking. As many as 20 different sulfides have been identified in the steam distillate and include diallyl mono to hexasulfides, allyl methyl mono to hexasulfides dimethyl mono to hexasulfides, and allyl 1-propenyl di and trisulfides [38]. 

Most of the studies on allicin have been conducted in-vitro, however, in-vivo studies on the activity of allicin carried out prove diat allicin has been transformed to other sulfides, S-allylmercaptocysteine (SAMC), or allyl mercaptan [37, 92]. Later, it has been demonstrated not to be an active compound in the body [91]. Neither allicin nor any other thiosulfinate has been detected in the human blood circulation [92] nor in the human breath [55] which shows that it reacts very rapidly with other species in the stomach, or intestine and its metabolites are thus considered the actual active compounds [93]. Surprisingly, allicin was shown that it might be harmful and that the iron in hemoglobin may rapidly be oxidized by the interaction with allicin in a dose of 0.2 mg/ml [91]. 

The flavor precursors, 5 -alk(en)yl-L-cysteine sulfoxides, themselves do not have any specific flavor. However, when garlic or onion cells are damaged by cutting or crushing and the 5 -alk(en)yl-L-cysteine sulfoxides meet the C-S lyase (alliinase), they are converted into various volatile sulfuric compounds. Stoll and Seebeck (1951) first proposed the production of diallyl thiosulfinate (allicin) from the 5 -allyl-L-cysteine sulfoxide (alliin) by the C-S lyase. Through the reaction catalyzed by the C-S lyase, 5 -alk(en)yl-L-cysteine sulfoxides yield alk(en)yl sulfenic acid and aminoacrylic acid, the latter being spontaneously degraded... 

Similar to the S-allyl-L-cysteine sulfoxide in garlic, the C-S lyase can also catalyze the flavor formation from the 5 -methyl-L-cysteine sulfoxide. Therefore, when garlic is cut or crushed, methyl sulfenic acid and allyl sulfenic acid can be produced from 5 -methyl-L-cysteine sulfoxide and S-allyl-L-cysteine sulfoxide, respectively (Figure 18.5). As sulfenic acids are quite reactive, methyl sulfenic acid and allyl sulfenic acid will quickly form the metiiyl 2-propenethiosulfinate and allyl methaneth-iosulfinate. With the similar reaction to that from diallyl thiosulfinate, these thiosulfinates produce allyl methyl disulfide and allyl methyl trisulfide. 

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