title: Medicaol, a strigolactone identified as a putative didehydro-orobanchol isomer, from Medicago truncatula.
abstract: A major strigolactone produced by the model legume Medicago truncatula (barrel medic) has been tentatively identified as a didehydro-orobanchol isomer. In this study, a putative didehydro-orobanchol isomer was isolated from root exudates collected from barrel medic grown hydroponically under phosphate-starved conditions. The structure and absolute configurations of this strigolactone, named medicaol, were determined by a combination of spectroscopic analysis and spectral comparison with 4-deoxymedicaol which was synthesized using solvolysis and rearrangement of hydroxymethylhexahydroindenone to tetrahydroazulenone as a key step. Medicaol has a seven-membered cycloheptadiene in the A ring instead of a typical six-membered cyclohexene. Medicaol and 4-deoxymedicaol showed activity comparable to their corresponding six-membered A ring relatives, orobanchol and 4-deoxyorobanchol (ent-2'-epi-5-deoxystrigol), in inducing hyphal branching of germinating spores of an arbuscular mycorrhizal fungus Gigaspora margarita. Plausible biosynthetic pathways from 4-deoxyorobanchol to medicaol are also proposed.
authors.affiliation: Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan.
authors.forename: Tamami
authors.initials: T
authors.lastname: Tokunaga
authors.affiliation: Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Hayashi
authors.affiliation: Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan. Electronic address: akiyama@biochem.osakafu-u.ac.jp.
authors.forename: Kohki
authors.initials: K
authors.lastname: Akiyama
mesh_terms: D007887:Fabaceae / Q000378:metabolism; D055137:Glomeromycota; D006576:Heterocyclic Compounds, 4 or More Rings; D007783:Lactones / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D046913:Medicago truncatula / Q000737:chemistry* / Q000378:metabolism; D038821:Mycorrhizae / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism; D010937:Plant Growth Regulators / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D018517:Plant Roots / Q000737:chemistry; D013559:Symbiosis
chemical_list: C528323:5-deoxystrigol; D006576:Heterocyclic Compounds, 4 or More Rings; D007783:Lactones; D010710:Phosphates; D010937:Plant Growth Regulators; C000598002:medicaol; C472678:orobanchol
keywords: Barrel medic; Fabaceae; Gigaspora margarita; Glomeromycota; Medicago truncatula; Strigolactone