DNA topoisomerase inhibitors: biflavonoids from Ouratea species

N.F. Grynberg, M.G. Carvalho, J.R. Velandia, M.C. Oliveira, I.C. Moreira, R. Braz- Filho, A. Echevarria
2002 Brazilian Journal of Medical and Biological Research  
Topoisomerase inhibitors are agents with anticancer activity. 7"-O-Methyl-agathisflavone (I) and amentoflavone (II) are biflavonoids and were isolated from the Brazilian plants Ouratea hexasperma and O. semiserrata, respectively. These biflavonoids and the acetyl derivative of II (IIa) are inhibitors of human DNA topoisomerases I at 200 µM, as demonstrated by the relaxation assay of supercoiled DNA, and only agathisflavone (I) at 200 µM also inhibited DNA topoisomerases II-α, as observed by
more » ... tenation and relaxation assays. The biflavonoids showed concentration-dependent growth inhibitory activities on Ehrlich carcinoma cells in 45-h culture, assayed by a tetrazolium method, with IC 50 = 24 ± 1.4 µM for I, 26 ± 1.1 µM for II and 10 ± 0.7 µM for IIa. These biflavonoids were assayed against human K562 leukemia cells in 45-h culture, but only I showed 42% growth inhibitory activity at 90 µM. Our results suggest that biflavonoids are targets for DNA topoisomerases and their cytotoxicity is dependent on tumor cell type.
doi:10.1590/s0100-879x2002000700009 pmid:12131922 fatcat:hvt5biaodrdtrf6lanxdxfwham