Garlic :)

[albert_dao]

Allicine (2-propene-1-sulfinothioic acid S-2-propenyl ester)
this is a chemical in garlic that when you cut it up
an enzyme in the garlic alliinase cleaves allicine into a new product
alliin this is a powerful antimicrobial and anti fungal agent

Some reading:

http://www.health-reports.com/allicin.html

Also note that allicin, when generated from fresh Garlic, is unstable, and quickly turns into other sulphur containing compounds. Due to Allicin's instability it is difficult for garlic based products to contain and maintain an Allicin content. I'm sure we can put two and two together on this one.