title: Antioxidant constituents in distillation residue of Awamori spirits.
abstract: Constituents in a distillation residue of Awamori (millet spirits) and their antioxidant activity are investigated in this study. The supernatant of the distillation residue obtained by centrifugation was partitioned with n-hexane, chloroform, ethyl acetate, and n-butanol against water to afford the corresponding solubles. Among them, n-hexane and chloroform solubles showed higher antioxidant potency than l-ascorbic acid by the bleomycin-Fe method. In chloroform solubles, seven cyclic dipeptides were identified along with ethyl 2-pyrrolidione-5-carboxylate, tyrosol, and ethyl p-hydoroxyphenyllactate. Antioxidant activity of ethyl p-hydoroxyphenyllactate was 4.2 times that of l-ascorbic acid, whereas cyclic dipeptides showed activity 0.89-1.29 times as strong as that of l-ascorbic acid. On the other hand, scavenging effect of cyclic dipeptides against O(2)(-.) and OH(.) by using electron spin resonance was also investigated. In the results, cyclo(l-Ile-l-Pro) showed significantly strong inhibitory effect against OH(.) (95.4% at 2.5 x 10-3 M) and cyclo(l-Phe-l-Pro), cyclo(l-Pro-l-Val), and cyclo(l-Leu-l-Pro) inhibited OH(.) 64.9, 54.1, and 51.0%, respectively, whereas alpha-tocopherol showed 37.7% inhibition, though only a few cyclic dipeptides weakly inhibited O(2)(-.).
authors.affiliation: Faculty of Pharmacy, Meijo University, Tempaku, Nagoya 468-8503, Japan.
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Takaya
authors.forename: Tadashi
authors.initials: T
authors.lastname: Furukawa
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Miura
authors.forename: Takashi
authors.initials: T
authors.lastname: Akutagawa
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Hotta
authors.forename: Naohisa
authors.initials: N
authors.lastname: Ishikawa
authors.forename: Masatake
authors.initials: M
authors.lastname: Niwa
mesh_terms: D000434:Alcoholic Beverages / Q000032:analysis*; D000975:Antioxidants / Q000032:analysis*; D001230:Aspergillus / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D005285:Fermentation; D016166:Free Radical Scavengers / Q000032:analysis; D012275:Oryza; D012995:Solubility
chemical_list: D000975:Antioxidants; D016166:Free Radical Scavengers