title: Isolation and identification of flavonoids accumulated in proanthocyanidin-free barley.
abstract: Flavonoids accumulated in proanthocyanidin-free near-isogenic lines iso ant 13, iso ant 17, and iso ant 22 of Nishinohoshi, developed by backcross breeding using a leading cultivar, Nishinohoshi, as a recurrent parent and a proanthocyanidin-free mutant as a nonrecurrent parent in Japan, were examined. A new flavanone, (2RS)-dihydrotricin 7-O-β-D-glucopyranoside (1), known flavanones (2RS)-dihydrotricin (2) and (2RS)-homoeriodictyol (3), and known flavones chrysoeriol 7-O-[α-L-rhamnopyranosyl-(1→6)-β-D-glucopyranoside] (4), chrysoeriol 7-O-β-D-glucopyranoside (5), tricin (6), and chrysoeriol (7) were isolated from iso ant 17 of Nishinohoshi. The structures and stereochemistries of the isolated flavonoids (1-7) were elucidated on the basis of spectroscopic analyses. The concentrations of the isolated flavonoids (1-7) in iso ant 13, iso ant 17, and iso ant 22 of Nishinohoshi were similar to each other, whereas the flavonoids 1-5 and 7 were not detected in Nishinohoshi, an old Japanese cultivar, Amaginijo, and North American cultivar Harrington. The concentration of tricin (6) in Nishinohoshi was a half those in iso ant 13, iso ant 17, and iso ant 22 of Nishinohoshi. Except for iso ant 13, iso ant 17, and iso ant 22 of Nishinohoshi, the concentration of tricin (6) was highest in Nishinohoshi, followed by Amaginijo and Harrington. Thus, tricin (6), its precursor dihydrotricin (2), and its glucopyranoside, dihydrotricin 7-O-β-D-glucopyranoside (1), as well as chrysoeriol (7) and homoeriodictyol (3) were accumulated in iso ant 13, iso ant 17, and iso ant 22 of Nishinohoshi probably by blocking at the step of flavanone 3-hydroxylase in the procyanidin biogenetic pathway, resulting in enhancement of the alternative biogenetic pathway.
authors.affiliation: National Agricultural Research Center for Kyushu Okinawa Region, National Agriculture and Food Research Organization, 496 Izumi, Chikugo, Fukuoka 833-0041, Japan. nakanohr@affrc.go.jp
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nakano
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Kawada
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Yoshida
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ono
authors.forename: Rika
authors.initials: R
authors.lastname: Iwaura
authors.forename: Takuji
authors.initials: T
authors.lastname: Tonooka
mesh_terms: D005419:Flavonoids / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D001467:Hordeum / Q000737:chemistry*; D007564:Japan; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D044945:Proanthocyanidins / Q000032:analysis*; D012639:Seeds / Q000737:chemistry*
chemical_list: D005419:Flavonoids; D044945:Proanthocyanidins; C013221:proanthocyanidin