Comparative evaluation of different Allium accessions for allicin and other allyl thiosulphinates

Allicin and other allyl thiosulphinates possess broad antimicrobial and health-promoting properties, which makes them natural and safe substitutes for synthetic preservatives. These thiosulphinate compounds were investigated in 33 Allium accessions representing 14 species, and these species differed significantly in their content of allicin, allyl methyl thiosulphinates (AMThs), and allyl trans-1-propenyl thiosulphinates (ATPThs) as ascertained using liquid chromatography tandem mass spectrometry. Total thiosulphinates were the highest in Allium sativum, Allium guttattun, Allium tuberosum, and Zimmu (an interspecific hybrid of Allium cepa L. and Allium sativum L). Allicin and other allyl thiosulphinates content was higher in flat and non-waxy leaves than in fistular and waxy leaves. Total thiosulphinates content was also significantly higher in cultivated and semi-domesticated species. Cluster analysis revealed that both foliage type and thiosulphinate content had played a major role in the clustering. These findings are useful in finding alternative sources of allicin and other thiosulphinates, and some of the accessions may serve as sources of natural preservatives for application in other research-related or commercial activities.