PROBLEM TO BE SOLVED: To provide a new cyclic peptide having a small molecular weight and bonding to Nrf2 (NF-E2-related factor 2) via KBD (Keap1 (=Kelch-like ECH-associated protein 1) binding domain), and to provide a screening method of a Keap1 bonding inhibition substance by using the peptide.SOLUTION: The cyclic peptide or its pharmacologically allowable salt includes a peptide expressed by general formula (I): Y1-Y2-Glu-Y3-Gly-Glu. In the formula, Y1 represents an asparagine residue or an aspartic acid residue Y2 represents an amino acid residue Y3 represents a threonine residue, a serine residue, an asparagine residue or an aspartic acid residue.COPYRIGHT: (C)2012,JPO&INPIT【課題】分子量が小さく、かつ、Nrf2とKBDを介して結合する新規環状ペプチド及びこれを用いたKeap1結合阻害物質のスクリーニング方法を提供する。【解決手段】以下の一般式(I)で示されるペプチドを含む環状ペプチド又はその薬理学的に許容される塩。Y1-Y2-Glu-Y3-Gly-Glu・・・(I)[式中、Y1は、アスパラギン残基又はアスパラギン酸残基を表し、Y2は、アミノ酸残基を表し、Y3は、スレオニン残基、セリン残基、アスパラギン残基又はアスパラギン酸残基を表す。]【選択図】なし
