Diallyl SulphidesThe diallyl sulphides (sulfides) obtained from garlic are less powerful than allicin but can still reportedly provide some benefits to health.
Diallyl sulphides are also less volatile than allicin. They do not degrade as quickly and, importantly, the health benefits survive cooking. Note that garlic still needs to be chopped or crushed to produce the sulphides - if garlic is cooked whole then it has almost no medicinal value or health benefits.
Diallyl sulphides do not share the antifungal properties of allicin. However they are reportedly good for the blood and circulation in some cases. The sulphides might also help to lower the levels of "bad" cholesterol, hence garlic might help to keep the heart and cardiovascular system healthy.
Diallyl suphides also have a reputation for boosting the immune system.
The garlic sulphides break down in the body within a few hours so for maximum health benefit it is best to have "a little often" as opposed to one large daily dose.
Before taking garlic or any other supplement, consult your doctor.