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Generation and Biological Evaluation of Degraded Derivatives of the Three E/Z‑Isomers of Yaku’amide B

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journal contribution
posted on 03.06.2021, 07:44 by Koichi Kamiya, Hiroaki Itoh, Masayuki Inoue
Potently cytostatic yaku’amide B (1) is a highly unsaturated linear tridecapeptide. During our synthetic studies of the E/Z-isomers of the α,β-dehydroisoleucines of 1, an unexpected retro-aldol reaction proceeded to transform E/Z-isomers 2, 3, and 4 into 2a, 3a, and 4a/4b, respectively. Compounds 2a, 3a, and 4a have a glycine at residue-1 instead of β-hydroxyisoleucine, and the β-hydroxyvaline at residue-8 in 4a is further replaced by glycine in 4b. Evaluation of the growth inhibition activities against MCF-7 cells revealed that 4b was approximately 10-fold weaker than the equipotent 24 and 2a4a, demonstrating the biological importance of a bulky side chain at residue-8.