title: Isolation and identification of phenolic compounds accumulated in brown rice grains ripened under high air temperature.
abstract: This study aimed to examine the compounds increasing or decreasing in concentration in brown rice grains ripened under high air temperature during ripening using a heat-tolerant cultivar Fusaotome, a heat-intolerant cultivar Hatsuboshi, and an intermediate cultivar Koshihikari. 6-O-Feruloylsucrose (1), 3',6-di-O-sinapoylsucrose (2), 3'-O-sinapoyl-6-O-feruloylsucrose (3), 3',6-di-O-feruloylsucrose (4), cycloartenyl ferulate (5), and 24-methylenecycloartanyl ferulate (6) were isolated from the extracts of brown rice grains. The structures of the isolated compounds (1-6) were elucidated on the basis of spectroscopic analyses. The mean concentrations of compounds 2, 3, and 6 in the grains ripened under high air temperature were markedly higher than those ripened under normal air temperature. In contrast, the mean concentration of compound 5 in the grains ripened under high air temperature was markedly lower than those ripened under normal air temperature. Thus, compounds 2, 3, 5, and 6 constitute potential biomarkers of heat stress in the cultivars used. The mean concentrations of compound 4 in the grains of Fusaotome were the highest in all cultivars. In contrast, the mean concentration of compound 5 in the grains of Fusaotome was the lowest. Therefore, the unique composition of heat-tolerant Fusaotome combines a high concentration of compound 4 with a low concentration of compound 5.
authors.affiliation: NARO Institute of Crop Science , 2-1-18 Kannondai, Tsukuba, Ibaraki 305-8518, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nakano
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ono
authors.forename: Norio
authors.initials: N
authors.lastname: Iwasawa
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Takai
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Arai-Sanoh
authors.forename: Motohiko
authors.initials: M
authors.lastname: Kondo
mesh_terms: D000388:Air / Q000032:analysis*; D006358:Hot Temperature; D012275:Oryza / Q000737:chemistry* / Q000254:growth & development / Q000378:metabolism; D010636:Phenols / Q000737:chemistry* / Q000378:metabolism; D010936:Plant Extracts / Q000737:chemistry* / Q000378:metabolism; D012639:Seeds / Q000737:chemistry / Q000254:growth & development* / Q000378:metabolism
chemical_list: D010636:Phenols; D010936:Plant Extracts