Regioselective synthesis of water-soluble monophosphate derivatives of combretastatin A-1

Rajendra P. Tanpure, Benson L. Nguyen, Tracy E. Strecker, Savannah Aguirre, Suman Sharma, David J. Chaplin, Bronwyn G. Siim, Ernest Hamel, John W. Lippert, George Pettit, Mary Lynn Trawick, Kevin G. Pinney

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


The natural products combretastatin A-4 (CA4) and combretastatin A-1 (CA1) are potent cancer vascular disrupting agents and inhibitors of tubulin assembly (IC 50 = 1-2 μM). The phosphorylated prodrugs CA4P and CA1P are undergoing human clinical trials against cancer. CA1 is unique due to its incorporation of a vicinal phenol, which has afforded the opportunity to prepare both diphosphate and regioisomeric monophosphate derivatives. Here, we describe the first synthetic routes suitable for the regiospecific preparation of the CA1-monophosphates CA1MPA (8a/b) and CA1MPB (4a/b). The essential regiochemistry necessary to distinguish between the two vicinal phenolic groups was accomplished with a tosyl protecting group strategy. Each of the four monophosphate analogues (including Z and E isomers) demonstrated in vitro cytotoxicity against selected human cancer cell lines comparable to their corresponding diphosphate congeners. Furthermore, Z-CA1MPA (8a) and Z-CA1MPB (4a) were inactive as inhibitors of tubulin assembly (IC 50 > 40 μM), as anticipated in this pure protein assay.

Original languageEnglish (US)
Pages (from-to)1568-1574
Number of pages7
JournalJournal of Natural Products
Issue number7
StatePublished - Jul 22 2011

ASJC Scopus subject areas

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


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