RESUMO
Bioguided fractionation of the roots of Citrus sinensis (Rutaceae) led to the isolation and identification of five coumarins, namely, clausarin, suberosin, poncitrin, xanthyletin and thamnosmonin, seven acridones, namely, acrimarine B, 2-methoxycitpressine I, citpressine I, buntanine, acrimarine E, honyumine and acrimarine C, and one terpenoid, namely, limonin. Among these compounds, clausarin, 2-methoxycitpressine I and acrimarine E inhibited P-glycoprotein-mediated drug efflux in K562/R7 human leukemic cells over-expressing P-glycoprotein.
Assuntos
Membro 1 da Subfamília B de Cassetes de Ligação de ATP/antagonistas & inibidores , Acridinas/isolamento & purificação , Acridinas/farmacologia , Citrus sinensis/química , Cumarínicos/isolamento & purificação , Cumarínicos/farmacologia , Acridonas , Linhagem Celular Tumoral , Humanos , Estrutura Molecular , Raízes de Plantas/químicaRESUMO
Multidrug resistance due to P-glycoprotein is a serious impediment to successful chemotherapy of cancer. Previous studies have shown that natural compounds such as prenyl flavonoids are able to modulate the multidrug resistance phenotype of P-glycoprotein-positive cancer cells. A fraction from the dichloromethane extract of a common Guadalupe Ficus, Ficus citrifolia was studied for its direct interaction with the purified C-terminal cytosolic domain of P-glycoprotein, and for its induced accumulation and cytotoxicity of vinblastine and daunomycin in two model cell lines overexpressing P-glycoprotein, namely K562/R7 and MESSA/Dx5. The fraction bound with high affinity to P-glycoprotein C-terminal cytosolic domain and was as efficient as cyclosporin A to increase intracellular accumulation of daunomycin in K562/R7 leukemic cells. Moreover, the fraction markedly enhanced the cytotoxic effect of vinblastine on the growth of MESSA/Dx5 cells. These results suggest that Ficus citrifolia possesses important therapeutic potential for improving the efficacy of cancer chemotherapy.
Assuntos
Membro 1 da Subfamília B de Cassetes de Ligação de ATP/metabolismo , Antineoplásicos Fitogênicos/farmacologia , Resistência a Múltiplos Medicamentos , Resistencia a Medicamentos Antineoplásicos , Rosales/metabolismo , Divisão Celular , Fracionamento Químico , Daunorrubicina/metabolismo , Fluorescência , Humanos , Líquido Intracelular/metabolismo , Células K562 , Extratos Vegetais/farmacologia , Células Tumorais Cultivadas , Vimblastina/metabolismoRESUMO
A benzophenone glycoside has been isolated from Davallia solida. Its structure was elucidated by chemical and spectral means as 4-O-beta-D-glucopyranosyl-2,6,4'-trihydroxybenzophenone. It bound with moderate affinity to the purified C-terminal cytosolic domain of P-glycoprotein, but the binding affinity was 6- to 10-fold increased for its aglycone derivative and other related benzophenones.