The Alliin-alliinase system

Allium species, such as onions, garhc and leeks are a rich source of sulphur-containing compounds, many of which are volatile and give rise to the characteristic flavour and aroma of these species. The volatile compounds are formed by the hydrolysis of non-volatile alkyl- 

The human metabolism of these sulphur compounds is complex and far from understood. Moreover, due to the complexity and number of potential products, it is difficult to generalize. Several compounds probably conjugate with glutathione post-absorption, and are metabolized via the mercapturic acid pathways, in a similar manner to isothiocyanates. N-acetyl-S-aUyl-L-cysteine (allylmercapturic acid), derived from diallyl disulphide, has been detected in urine from humans who have consumed garlic (de Rooji et al. 1996). The characteristic breath and perspiration odours foimd following garlic consumption are 

Dipropyl sulphide Dipropyl disulphide Dipropyl trisulphide 

Propyl methyl sulphide Propyl methyl disulphide 

Allyl methyl sulphide Allyl methyl disulphide Allyl methyl trisulphide 

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