- Synthesis and biological evaluation of analogues of the marine cyclic depsipeptide obyanamide
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On the basis of the total synthesis of obyanamide, 20 analogues of this marine cyclic depsipeptide have been synthesized by (i) preparation of the tripeptide fragments in the western hemisphere using Z/OtBu protocol; (ii) preparation of the dipeptide fragments in the eastern hemisphere using Boc/OMe protocol; and (iii) fragments coupling, removal of protecting groups (Boc and OtBu, in one pot), and macrocyclizaion in the last step. The cytotoxic test showed that three synthetic compounds exhibited moderate activities against HL-60, KB, LOVO, and A549 cell lines. According to the results, the β-amino acid residue was found to play a critical role in the biological activities. Additionally, the ester bond along with the Ala(Thz) moiety was also essential for biological activities. However, it seems too early to draw a conclusion that the N-methylation of Val/Phe can lead to higher or lower cytotoxic activities.
- Zhang, Wei,Ding, Ning,Li, Yingxia
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- Studies of Unusual Amino Acids and Their Peptides. XVII. The Synthesis of Peptides Containing N-Carboxymethyl Amino Acids. II.
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The synthetic routes were investigated to four kinds of tetrapeptides made up of three usual amino acid residues and one N-carboxymethyl (Cm-) amino acid residue.The application of vacuum distillation made the isolation of a Cm-amino acid diester more convenient and efficient compared with the chromatographic methods which had been used previously.The efficiency of peptide bond formation at the imino group of a Cm-amino acid by the acid chloride method was remarkably improved under suitable reaction conditions.In the elongation of the peptide chain from a peptide containing a Cm-amino acid at the C-terminal position, the coupling efficiency was usually poorer than that in the case of the corresponding peptide composed only of the usual amino acid residues, and it depended greatly on the coupling methods, the 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide-1-hydroxybenzotriazole method being generaly the most desirable.
- Miyazawa, Toshifumi,Hiramatsu, Shin'ichi,Tsuboi, Yasuhiro,Yamada, Takashi,Kuwata, Shigeru
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p. 1976 - 1982
(2007/10/02)
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