Latent production of angiotensin I-converting enzyme inhibitors from buckwheat protein

Authors

  • Chun-Hui Li,

    1. Faculty of Agriculture, Division of Bioresource and Bioenvironmental Sciences, Graduate School Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
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  • Toshiro Matsui,

    Corresponding author
    1. Faculty of Agriculture, Division of Bioresource and Bioenvironmental Sciences, Graduate School Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
    • Institute of Food Biotechnology, Division of Bioresource and Bioenvironmental Sciences, Graduate School of Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.
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  • Kiyoshi Matsumoto,

    1. Faculty of Agriculture, Division of Bioresource and Bioenvironmental Sciences, Graduate School Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
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  • Rikio Yamasaki,

    1. Matsumoto Factory, Nikkoku Flour Mills Co. Ltd, 2-6-52 Minamimatsumoto, Matsumoto 390-0832, Japan
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  • Terukazu Kawasaki

    1. Institute of Health and Sport Science Kyushu Sangyo University, 2-3-1 Matsukadai, Higashi-ku, Fukuoka 813-8503, Japan
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Abstract

The latent production of angiotensin I-converting enzyme (ACE) inhibitors from tartary buckwheat (BW) was investigated, and the peptides responsible for ACE inhibition characterized. Intact buckwheat was found to exhibit ACE inhibitory activity having an IC50 value of 3.0 mg/ml. The activity of the protein fraction (IC50: 0.36 mg protein/ml) was not enhanced by pepsin treatment. Pepsin, followed by chymotrypsin and trypsin hydrolysis, resulted in a significant increase in the ACE inhibitory activity (IC50: 0.14 mg protein/ml). The rutin contained in the buckwheat did not exhibit any ACE inhibition. A single oral administration of BW digest lowered the systolic blood pressure of a spontaneously hypertensive rat. Thus, BW proteins offer a potential resource for producing ACE inhibitory peptides during the digestion process. From the di-/tri-peptide fraction (DTPF) of the BW digest, inhibitory peptides were identified. The magnitude (%) of the total ACE inhibitory contribution of each identified peptide, relative to the overall inhibition of the DTPF, was about 41%. Copyright © 2002 European Peptide Society and John Wiley & Sons, Ltd.

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