Allicin decomposition

Alliin-inosine 5 -monophosphate thermal interactions, 188-197 Allium chemistry allicin decomposition, 67-68 previous studies, 64-66 natural flavor identification, 63-64 product formation from chopped garlic, 65... 

Allicin 1. 3-Acetyl-6- methoxybenz- aldehyde 1. Ethylene 1. Decomposition products of amygdalin... 

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. 

Attempts by Brodnitz et al. in 1971 to determine allicin by gas chromatography-mass spectrometry (GC-MS) provided evidence for an unusual mode of decomposition (70). They indicated that GC caused diallyl thiosulfinate to dehydrate according to the reaction C6HiqS20 -> C gS2 + H2O, affording a 2.4 1 mixture of two compounds, claimed (incorrectly as we shall see below) to be 3-vinyl-4H-l,2-dithiin (10, equation 1) and 3-vinyl-6H-l,2-dithiin (10a, equation 1) (70). Analytical methods for allicin quantitation that rely on GC detection of compounds 10 and 10a are still used (77), even though serious problems exist with this method and more accurate high-performance liquid chromatographic (HPLC) methods have been developed (see below). 

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