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1.
Rev. bras. farmacogn ; 18(supl): 703-708, Dec. 2008. ilus, tab
Article in Portuguese | LILACS | ID: lil-509448

ABSTRACT

Este trabalho descreve o efeito inibitório de rubrofusarina (5,6-diidroxi-8-metoxi-2-metilbenzo[g]cromen-4-ona, 1) sobre a enzima DNA topoisomerase II-α humana. Rubrofusarina mostrou total inibição da enzima topisomerase II-α na concentração de 120 µM. Este resultado é semelhante ao observado com etoposida, utilizada como controle positivo. Para a realização deste teste, rubrofusarina foi isolada de Senna macranthera var. nervosa (Voguel) Irwin & Barnebyem e caracterizada por métodos espectroscópicos, incluindo RMN 2D, do produto natural bem como de seu derivado monoacetilado.


This work describes the inhibitory effect of rubrofusarin (5,6-dihydroxy-8-methoxy-2-methylbenzo[g]cromen-4-one, 1) against human DNA topoisomerase II-α. The results for relaxation assays showed total inhibition of topisomerase II-α by rubrofusarin at 120 µM. This result is comparable to the one observed with etoposide as positive control. For this study, rubrofusarin was isolated from Senna macranthera var. nervosa (Voguel) Irwin & Barnebyem and characterized by spectral data, including 2D NMR, as well as its acetylated derivative.

2.
Planta Med ; 71(6): 561-3, 2005 Jun.
Article in English | MEDLINE | ID: mdl-15971129

ABSTRACT

The biflavonoid 2'',3''-diidroochnaflavone ( 1), isolated from the leaves of Luxemburgia nobilis, was cytotoxic to murine Ehrlich carcinoma (IC50 = 17.2 microM) and human leukemia K562 cells (IC50 = 89.0 microM) in a concentration-dependent manner in 45 h cell culture. The acetyl (1a) and methyl (1b) derivatives of 1 were not cytotoxic to these tumour cells at 67.0 and 82.0 microM concentrations, respectively. Biflavonoid 1 as well 1a inhibit the activity of human DNA topoisomerases I and II-alpha as observed in relaxation and decatenation assays. In addition, we show that 1 is a DNA interacting agent, which causes DNA unwinding in an assay with topoisomerase I. Also, spectrophotometric titration of 1 with DNA resulted in a pronounced hypochromic effect.


Subject(s)
Antineoplastic Agents, Phytogenic/pharmacology , Enzyme Inhibitors/pharmacology , Ochnaceae , Phytotherapy , Plant Extracts/pharmacology , Topoisomerase I Inhibitors , Animals , Antineoplastic Agents, Phytogenic/administration & dosage , Antineoplastic Agents, Phytogenic/therapeutic use , Biflavonoids/administration & dosage , Biflavonoids/pharmacology , Biflavonoids/therapeutic use , Cell Line, Tumor/drug effects , Dose-Response Relationship, Drug , Enzyme Inhibitors/administration & dosage , Enzyme Inhibitors/therapeutic use , Humans , Inhibitory Concentration 50 , Mice , Plant Extracts/administration & dosage , Plant Extracts/therapeutic use
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