The characteristic odor and flavor of ginger is caused by a mixture of zingerone, shogaols and gingerols, volatile oils that compose one to three percent of the weight of fresh ginger. In laboratory animals, the gingerrols increase the motility of the gastrointestinal tract and have analgesic, sedative, antipyretic and antibacterial properties.Ginger oil has been shown to prevent skin cancer in mice and a study at the University of Michigan demonstrated that gingerrols can kill ovarian cancer cells. Ginger contains up to three percent of a fragrant essential oil whose main constituents are sesquiterpenoids, with (-)-zingiberene as the main component. Smaller amounts of other sesquiterpenoids (β- sesquiphellandrene, bisabolene and farnesene) and a small monoterpenoid fraction (β-phelladrene, cineol, and citral) have also been identified. (Wikipedia)