Synthesis of phakellistatin 11: A Micronesia (Chuuk) marine sponge cyclooctapeptide

George Pettit, J. W. Lippert, S. R. Taylor, R. Tan, M. D. Williams

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34 Scopus citations


The cyclic octapeptide phakellistatin 11 (1), a constituent of The Federated States of Micronesia (Chuuk) marine sponge Phakellia sp., was synthesized using solid-phase techniques. An initial solution-phase synthesis proved to be inadequate owing to spontaneous deprotection of the Fmoc group at the heptapeptide stage. Using the PAL resin attachment and proceeding from Fmoc-Glu-α-allyl ester, linear elongation of the octapeptide was performed until the final unit Pro was added. The allyl ester was removed using Pd0[P(C6H5)3]4. Cleavage of the final Fmoc group and cyclization with PyAOP provided phakellistatin 11 (1) in 17% overall yield. The synthetic specimen of phakellistatin 11 (1) was found to be chemically but not biologically (cancer cell lines) identical to the natural product. The result suggested a conformational difference or more likely the presence of a trace amount of a highly active antineoplastic agent that binds noncovalently to the natural cyclic octapeptide 1.

Original languageEnglish (US)
Pages (from-to)883-891
Number of pages9
JournalJournal of Natural Products
Issue number7
StatePublished - 2001

ASJC Scopus subject areas

  • Analytical Chemistry
  • Molecular Medicine
  • Pharmacology
  • Pharmaceutical Science
  • Drug Discovery
  • Complementary and alternative medicine
  • Organic Chemistry


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