Onion (Allium cepaL.)

Onions are a very common and rich source of dietary flavonoids, and contain three diverse and highly valuable phytochemicals in perfect proportion: flavonoids, fructans, and organosulfur compounds. Phytochemicals have the potential to promote health benefits in humans and offer protection from a variety of diseases, including cancer. Apart from the main sulfur and flavonoid constituents, several other constituents of intact onion, such as lectins (the most abundant proteins in onion), prostaglandins, fructan, pectin, adenosine, vitamins B1, B2, B6, C, and E, biotin, nicotinic acid, fatty acids, glycolipids, phospholipids, and essential amino acids, have been studied for their biological effects over several decades. Several epidemiologic studies have reported that the antiplatelet activity of onions is considered to be a property of organosulfur compounds. In particular, a class of α-sulfinyl-disulfides (cepaenes), found in onion extracts, has demonstrated antithrombotic activity.