 Ultrasound-assisted and microwave-assisted extraction methods provide more rapid extraction rates with lower energy costs.Other important essential oil constituents of clove oil include acetyl eugenol, beta-caryophyllene, vanillin, crategolic acid, tannins such as bicornin, gallotannic acid, methyl salicylate (painkiller), the flavonoids eugenin, kaempferol, rhamnetin, and eugenitin, triterpenoids such as oleanolic acid, stigmasterol, and campesterol and several sesquiterpenes.Eugenol has not been classified for its potential toxicity.