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Updated: May 17, 2026

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Published on: April 28, 2016
Production of dipeptidyl peptidase IV inhibitory peptides from defatted rice bran
Tadashi Hatanaka1, Yosikazu Inoue, Jiro Arima
1Okayama Prefectural Technology Center for Agriculture, Forestry, and Fisheries, Research Institute for Biological Sciences (RIBS), Okayama, 7549-1 Kibichuo-cho, Kaga-gun, Okayama 716-1241, Japan. hatanaka@bio-ribs.com
Abstract:
The insulinotropic hormone glucagon-like peptide-1 is metabolised extremely rapidly by the ubiquitous enzyme dipeptidyl peptidase IV (DPP-IV). Therefore, human DPP-IV is a key regulator involved in the prevention and treatment of type 2 diabetes. To simplify the method of producing an inhibitory peptide against DPP-IV, we focused on rice bran (RB) as a source and subjected proteins from defatted RB to enzymatic proteolysis using 2 commercial enzymes. The RB peptides produced with Umamizyme G exhibited 10 times the inhibitory activity as those produced with Bioprase SP. The half-maximal inhibitory concentration (IC(50)) value of the RB peptides was 2.3 ± 0.1mg/ml. Leu-Pro and Ile-Pro were identified as the inhibitory peptides among the RB peptides produced with Umamizyme G. Ile-Pro was the strongest DPP-IV inhibitor among the 15 Xaa-Pro dipeptides and Pro-Ile tested. Ile-Pro competitively inhibited DPP-IV (K(i)=0.11 mM). Mass spectrometry indicated that the contents of Leu-Pro and Ile-Pro in the RB peptides were 2.91 ± 0.52 μg/mg.
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