Isol. from leaves of the curryleaf (Murraya koenigii) and from star anise oil (Illicium religiosum) It is a precursor in the synthesis of the insecticide synergist piperonyl butoxide and the recreational drug MDMA ("Ecstacy."); Safrole is a natural plant constituent, found in oil of sassafras and certain other essential oils. It is a member of the methylenedioxybenzene group of compounds, many of which (e.g. piperonyl butoxide) are extensively used as insecticide synergists. A major source of human exposure to safrole is through consumption of spices, such as nutmeg, cinnamon and black pepper, in which safrole is a constituent. Safrole is also present in root beer, and has been used as an additive in chewing gum, toothpaste, soaps and certain pharmaceutical preparations. Safrole is a weak hepatocarcinogen and it is a matter of considerable interest whether the ally1 moiety or the methylenedioxy group, or both, are involved in the mechanism of its carcinogenesis. Safrole is extensively metabolized, giving rise to a large number of metabolites. Metabolism involves essentially two major routes, oxidation of the ally1 side chain, and oxidation of the methylenedioxy group with subsequent cleavage to form the catechol. Safrole undergoes oxidation of the allylic group to yield the 2, 3-epoxide (safrole epoxide). The dihydrodiol is one of the metabolites of safrole, and presumably arises from the hydration of the 2, 3-epoxide. The principal route of metabolism of safrole is through cleavage of the methylenedioxy group, the major metabolites being allylcatechol and its isomer, propenylcatechol. Eugenol and its isomer I-methoxy- 2-hydroxy-4-allylbenzene have been detected as minor metabolites in the rat, mouse and man. (PMID: 6719936); Safrole, also known as shikimol, is a colorless or slightly yellow oily liquid. It is typically extracted from the root-bark or the fruit of sassafras plants in the form of sassafras oil, or synthesized from other related methylenedioxy compounds. It is the principal component of brown camphor oil, and is found in small amounts in a wide variety of plants, where it functions as a natural pesticide. The Ocotea cymbarum[verification needed] oil made of the Ocotea pretiosa[verification needed], a plant growing in Brazil, and sassafras oil made of Sassafras albidum, a tree growing in eastern North America, are the main natural sources for safrole. It has a characteristic "candy-shop" aroma.