Antioxidant Constituents in Distillation Residue of Awamori Spirits

• Published in: Journal of agricultural and food chemistry 2007-01, Vol.55 (1), p.75-79
• Main Authors: Takaya, Yoshiaki, Furukawa, Tadashi, Miura, Shunsuke, Akutagawa, Takashi, Hotta, Yoshihiro, Ishikawa, Naohisa, Niwa, Masatake
• Format: Article
• Language: English
• Subjects: Alcoholic Beverages - analysis; antioxidant activity; antioxidants; Antioxidants - analysis; Aspergillus - metabolism; Awamori; Biological and medical sciences; cyclic dipeptides; cyclic peptides; distillation; distillation residues; distilled spirits; Electron Spin Resonance Spectroscopy; Fermentation; Food industries; Free Radical Scavengers - analysis; free radicals; Fundamental and applied biological sciences. Psychology; millets; Oryza; Solubility
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf062029d

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 O2 -• 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 × 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 α-tocopherol showed 37.7% inhibition, though only a few cyclic dipeptides weakly inhibited O2 -•. Keywords: Awamori; distillation residue; Aspergillus awamori; cyclic dipeptide; antioxidant; bleomycin; ESR; hydroxyl radical; superoxide