title: Eugenol and isoeugenol, characteristic aromatic constituents of spices, are biosynthesized via reduction of a coniferyl alcohol ester.
abstract: Phenylpropenes such as chavicol, t-anol, eugenol, and isoeugenol are produced by plants as defense compounds against animals and microorganisms and as floral attractants of pollinators. Moreover, humans have used phenylpropenes since antiquity for food preservation and flavoring and as medicinal agents. Previous research suggested that the phenylpropenes are synthesized in plants from substituted phenylpropenols, although the identity of the enzymes and the nature of the reaction mechanism involved in this transformation have remained obscure. We show here that glandular trichomes of sweet basil (Ocimum basilicum), which synthesize and accumulate phenylpropenes, possess an enzyme that can use coniferyl acetate and NADPH to form eugenol. Petunia (Petunia hybrida cv. Mitchell) flowers, which emit large amounts of isoeugenol, possess an enzyme homologous to the basil eugenol-forming enzyme that also uses coniferyl acetate and NADPH as substrates but catalyzes the formation of isoeugenol. The basil and petunia phenylpropene-forming enzymes belong to a structural family of NADPH-dependent reductases that also includes pinoresinol-lariciresinol reductase, isoflavone reductase, and phenylcoumaran benzylic ether reductase.
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, University of Michigan, 830 North University Street, Ann Arbor, MI 48109-1048, USA.
authors.forename: Takao
authors.initials: T
authors.lastname: Koeduka
authors.forename: Eyal
authors.initials: E
authors.lastname: Fridman
authors.forename: David R
authors.initials: DR
authors.lastname: Gang
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Vassão
authors.forename: Brenda L
authors.initials: BL
authors.lastname: Jackson
authors.forename: Christine M
authors.initials: CM
authors.lastname: Kish
authors.forename: Irina
authors.initials: I
authors.lastname: Orlova
authors.forename: Snejina M
authors.initials: SM
authors.lastname: Spassova
authors.forename: Norman G
authors.initials: NG
authors.lastname: Lewis
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Noel
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Baiga
authors.forename: Natalia
authors.initials: N
authors.lastname: Dudareva
authors.forename: Eran
authors.initials: E
authors.lastname: Pichersky
mesh_terms: D004952:Esters / Q000378:metabolism; D005054:Eugenol / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism*; D017343:Genes, Plant / Q000235:genetics; D006841:Hydrocarbons, Aromatic / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018649:Ocimum basilicum / Q000201:enzymology* / Q000235:genetics; D032306:Petunia / Q000201:enzymology* / Q000235:genetics; D010636:Phenols / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017365:Spices; D013379:Substrate Specificity
chemical_list: D004952:Esters; D006841:Hydrocarbons, Aromatic; D010636:Phenols; D010940:Plant Proteins; D005054:Eugenol; C036643:isoeugenol; C010559:coniferyl alcohol; D009247:NADH, NADPH Oxidoreductases