Inhibition of oncogene product enzyme activity as an approach to cancer chemoprevention. Tyrosine-specific protein kinase inhibition by purpurogallin from Quercus sp. nutgall

Mohamed Abou-Karam, W. Thomas Shier

Research output: Contribution to journalArticle

26 Scopus citations

Abstract

Inhibitors of oncogene product enzyme activity were sought as a prescreen for potential cancer chemopreventive agents. Purpurogallin, a polyphenol from Quercus sp. nutgall, was found to inhibit the tyrosine-specific protein kinase of the human erb-b oncogene product (epidermal growth factor receptor) for both autophosphorylation (IC50=27.5 μM) and phosphorylation of an exogenous substrate (IC50= 45.3 μM). An examination of enzyme kinetics indicated that purpurogallin is a competitive inhibitor of both ATP (K(i) = 54.9 μM for autophosphorylation, K(i) = 33.9 μM for phosphorylation of exogenous substrate) and the tyrosine-containing acceptor substrate poly(glutamate, alanine, tyrosine) 6:3:1 (K(i) = 83.7 μM).

Original languageEnglish (US)
Pages (from-to)337-340
Number of pages4
JournalPhytotherapy Research
Volume13
Issue number4
DOIs
StatePublished - Jun 1 1999

Keywords

  • Cancer chemopreventive agent
  • Epidermal growth factor receptor
  • Oncogene
  • Purpurogallin
  • Tyrosine-specific protein kinase inhibitor

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