Falcarinol

Falcarinol (1,9-heptadecadiene-4,6-diyn-3-ol) is a natural pesticide and fatty alcohol found in carrots and red ginseng (Panax ginseng), which protects them from fungal diseases, such as liquorice rot that causes black spots on the roots during storage. Falcarinol is a polyyne with two carbon carbon triple bonds and two double bonds. At higher concentrations like in ivy, falcarinol is capable to induce a allergic reaction (contact dermatitis).

Falcarinol is thought to reduce the risk of developing cancer, as a research team from the University of Newcastle upon Tyne found in February 2005.

See the BBC article: Carrots may help ward off cancer