Two Novel Hexadepsipeptides with Several Modified Amino Acid Residues Isolated from the Fungus <i>Isaria</i>

DOI Web Site Web Site 被引用文献2件

抄録

<jats:title>Abstract</jats:title><jats:p>Two new cyclohexadepsipeptides have been isolated from the fungus <jats:italic>Isaria.</jats:italic> Fungal growth in solid media yielded hyphal strands from which peptide fractions were readily isolable by organic‐solvent extraction. Two novel cyclodepsipeptides, isaridin A and isaridin B, have been isolated by reverse‐phase HPLC, and characterized by ESI‐MS and <jats:sup>1</jats:sup>H‐NMR. Single crystals of both peptides have been obtained, and their 3D structures were elucidated by X‐ray diffraction. The isaridins contain several unusual amino acid residues. The sequences are cyclo(<jats:italic>β</jats:italic>‐Gly‐HyLeu‐Pro‐Phe‐NMeVal‐NMePhe) and cyclo(<jats:italic>β</jats:italic>‐Gly‐HyLeu‐<jats:italic>β</jats:italic>‐MePro‐Phe‐NMeVal‐NMePhe), where NMeVal is <jats:italic>N</jats:italic>‐methylvaline, NMePhe <jats:italic>N</jats:italic>‐methylphenylalanine, and HyLeu hydroxyleucine (=2‐hydroxy‐4‐methylpentanoic acid). The two peptides differ from one another at residue 3, isaridin A having an (<jats:italic>S</jats:italic>)‐proline at this position, while <jats:italic>β</jats:italic>‐methyl‐(<jats:italic>S</jats:italic>)‐proline (=(2<jats:italic>S</jats:italic>,3<jats:italic>S</jats:italic>)‐2,3,4,5‐tetrahydro‐3‐methyl‐1<jats:italic>H</jats:italic>‐pyrrole‐2‐carboxylic acid) is found in isaridin B. The solid‐state conformations of both cyclic depsipeptides are characterized by the presence of two <jats:italic>cis</jats:italic> peptide bonds at HyLeu(2)‐Pro(3)/HyLeu(2)‐<jats:italic>β</jats:italic>‐MePro(3) and NMeVal(5)‐NMePhe(6), respectively. In isaridin A, a strong intramolecular H‐bond is observed between Phe(4)CO⋅⋅⋅HN<jats:italic>β</jats:italic>‐Gly(1), and a similar, but weaker, interaction is observed between <jats:italic>β</jats:italic>‐Gly(1)CO⋅⋅⋅HNPhe(4). In contrast, in isaridin B, only a single intramolecular H‐bond is observed between <jats:italic>β</jats:italic>‐Gly(1)CO⋅⋅⋅HNPhe(4).</jats:p>

収録刊行物

被引用文献 (2)*注記

もっと見る

キーワード

詳細情報 詳細情報について

問題の指摘

ページトップへ