Inhibition of topoisomerase I function by nitidine and fagaronine

Li Kai Wang, Sidney Hecht, Sidney M. Hecht

Research output: Contribution to journalArticle

133 Citations (Scopus)

Abstract

The benzophenanthridine alkaloids nitidine and fagaronine were characterized as inhibitors of topoisomerase I function. In common with the antitumor agent camptothecin, both nitidine and fagaronine stabilized the covalent binary complex formed between calf thymus topoisomerase I and DNA. The effects of these compounds were readily apparent at 0.15-0.3 μM concentrations. Both nitidine and fagaronine inhibited the topoisomerase I-mediated relaxation of supercoiled pSP64 plasmid DNA more effectively than camptothecin; unlike camptothecin, both of these benzophenanthridine alkaloids also bound directly to and mediated the unwinding of B-form DNA. Nitidine and fagaronine were also studied in comparison with camptothecin to determine the sequence specificity of DNA breaks produced from a 32P-end-labeled duplex in the presence of topoisomerase I. All three compounds produced very similar cleavage patterns. The specificity of nitidine and fagaronine for inhibiting topoisomerase I function was studied by measuring the effects of the compounds on the unknotting of P4 DNA by calf thymus topoisomerase II. Moderate inhibition of topoisomerase II-mediated unknotting was obtained, but only in the presence of high (i.e., 40 μM) concentrations of nitidine and fagaronine. In comparison, doxorubicin inhibited topoisomerase II to the same extent as nitidine and fagaronine when it was employed at 2.5 μM concentration and was strongly inhibitory when employed at 10 μM concentration.

Original languageEnglish (US)
Pages (from-to)813-818
Number of pages6
JournalChemical Research in Toxicology
Volume6
Issue number6
StatePublished - 1993
Externally publishedYes

Fingerprint

Type I DNA Topoisomerase
Camptothecin
Type II DNA Topoisomerase
Benzophenanthridines
Alkaloids
Topoisomerase I Inhibitors
B-Form DNA
Thymus
DNA Breaks
DNA
fagaronine
nitidine
Antineoplastic Agents
Doxorubicin
Thymus Gland
Plasmids

ASJC Scopus subject areas

  • Drug Discovery
  • Organic Chemistry
  • Chemistry(all)
  • Toxicology
  • Health, Toxicology and Mutagenesis

Cite this

Inhibition of topoisomerase I function by nitidine and fagaronine. / Wang, Li Kai; Hecht, Sidney; Hecht, Sidney M.

In: Chemical Research in Toxicology, Vol. 6, No. 6, 1993, p. 813-818.

Research output: Contribution to journalArticle

Wang, Li Kai ; Hecht, Sidney ; Hecht, Sidney M. / Inhibition of topoisomerase I function by nitidine and fagaronine. In: Chemical Research in Toxicology. 1993 ; Vol. 6, No. 6. pp. 813-818.
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