RESUMO
Previous studies indicated the need of at least one phenolic hydroxyl group in the coumarin core for induction of cytotoxicity in different cell lines. Herein, we present an exhaustive structure-activity relationship study including ortho-dihydroxycoumarins (o-DHC) derivatives, cinnamic acid derivatives (as open-chain coumarin analogues) and 1,2-pyrones (representative of the δ-lactone ring of the coumarin core), carried out to further identify the structural features of o-DHC required to induce leukemic cell differentiation and apoptosis in U-937 cells. Our results show for the first time that the δ-lactone ring positively influences the aforementioned biological effects, by conferring greater potency to compounds with an intact coumarin nucleus. Most tellingly, we reveal herein the crucial role of this molecular portion in determining the selective toxicity that o-DHC show for leukemic cells over normal blood cells. From a pharmacological perspective, our findings point out that o-DHC may be useful prototypes for the development of novel chemotherapeutic agents.
Assuntos
Apoptose/efeitos dos fármacos , Lactonas/química , Leucócitos Mononucleares/efeitos dos fármacos , 4-Hidroxicumarinas/síntese química , 4-Hidroxicumarinas/química , 4-Hidroxicumarinas/farmacologia , Ciclo Celular/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Cinamatos/síntese química , Cinamatos/química , Cinamatos/farmacologia , Relação Dose-Resposta a Droga , Avaliação Pré-Clínica de Medicamentos , Humanos , Células Jurkat , Leucócitos Mononucleares/citologia , Pironas/síntese química , Pironas/química , Pironas/farmacologia , Relação Estrutura-Atividade , Células U937RESUMO
Chemotherapeutics represent the main approach for the treatment of leukemia. However, the occurrence of adverse side effects and the complete lack of effectiveness in some cases make it necessary to develop new drugs. As part of our screening program to evaluate the potential chemotherapeutic effect of natural coumarins, we investigated the anti-leukemic activities of a series of six prenylated coumarins isolated from the stem bark of Toddalia asiatica (Rutaceae). Among these, 6-(3-methyl-2-butenyl)-5,7-dimethoxycoumarin (toddaculin) displayed the most potent cytotoxic and anti-proliferative effects in U-937 cells. To determine whether these effects resulted from induction of cell death or differentiation, we further evaluated the expression of several apoptosis and maturation markers. Interestingly, while toddaculin at 250 µM was able to induce apoptosis in U-937 cells, involving decreased phosphorylation levels of ERK and Akt, 50 µM toddaculin exerted differentiating effects, inducing both the capacity of U-937 cells to reduce NBT and the expression of differentiation markers CD88 and CD11b, but no change in p-Akt or p-ERK levels. Taken together, these findings indicate that toddaculin displays a dual effect as a cell differentiating agent and apoptosis inducer in U-937 cells, suggesting it may serve as a pharmacological prototype for the development of novel anti-leukemic agents.
Assuntos
Antineoplásicos Fitogênicos/farmacologia , Apoptose/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Cumarínicos/farmacologia , Leucemia/patologia , Rutaceae/química , Antineoplásicos Fitogênicos/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Cumarínicos/química , Regulação para Baixo/efeitos dos fármacos , Ensaios de Seleção de Medicamentos Antitumorais , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Humanos , Leucemia/tratamento farmacológico , Leucemia/metabolismo , MAP Quinase Quinase 4/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismoRESUMO
The presumption that some coumarins might be lead compounds in the search for new differentiation agents against leukemia is based on the fact that natural coumarins, 5-(3-methyl-2-butenyloxy)-6,7-methylenedioxycoumarin (C-2) and 5-methoxy-6,7-methylenedioxycoumarin (C-1) inhibit proliferation and induce differentiation in U-937 cells [Riveiro, M. E.; Shayo, C.; Monczor, F.; Fernandez, N.; Baldi, A.; De Kimpe, N.; Rossi, J.; Debenedetti, S.; Davio, C. Cancer Lett.2004, 210, 179-188]. These promising findings prompted us to investigate the anti-leukemia activity of a broader range of related polyoxygenated coumarins. Twenty related natural or synthetically prepared coumarins, including a range of 5-substituted ayapin derivatives which have become easy accessible via newly developed synthesis methods, were evaluated, where treatments with 5-(2,3-dihydroxy-3-methylbutoxy)-6,7-methylenedioxycoumarin (D-3) and 5-(2-hydroxy-3-methoxy-3-methylbutoxy)-6,7-methylenedioxycoumarin (D-2) were able to inhibit the cell growth and induce the differentiation of U-937 cells after 48 h treatment. These results provide insight into the correlation between some structural properties of polyoxygenated coumarins and their in vitro leukemic differentiation activity.
Assuntos
Antineoplásicos/farmacologia , Diferenciação Celular/efeitos dos fármacos , Cumarínicos/farmacologia , Leucemia/tratamento farmacológico , Oxigênio/química , Antineoplásicos/síntese química , Antineoplásicos/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Cumarínicos/síntese química , Cumarínicos/química , Humanos , Relação Estrutura-AtividadeRESUMO
In the present study, we sought to establish the effect of diverse structural-related hydroxycoumarins on the proliferation, cytotoxicity, and induction of apoptosis in promonocytic leukemic cells (U-937). The dihydroxylated coumarins, 7,8-dihydroxy-coumarin and esculetin, induced DNA fragmentation as well as characteristic morphological changes of programmed cell death in U-937 cells. With the aim to perform a structure-activity relationship study, the correlation between the physicochemical properties of the molecules and their pro-apoptotic activity was carried out. Results showed that the presence of two adjacent phenolic hydroxyl groups was the most important factor in terms of the SAR. The exposure of leukemic cells to 7,8-dihydroxy-coumarin evoked a phenoxyl radical generation that was detected by electron spin resonance spectroscopy. The present study suggests that reactive oxygen species generation plays a critical role in dihydroxycoumarin-induced apoptosis in U-937 cells. These findings further suggest that these compounds may have a potential therapeutic role in the treatment of hematological malignancies.
Assuntos
Apoptose/efeitos dos fármacos , Cumarínicos/síntese química , Cumarínicos/farmacologia , Produtos Biológicos/química , Produtos Biológicos/farmacologia , Cumarínicos/química , Espectroscopia de Ressonância de Spin Eletrônica , Humanos , Hidroxilação , Cinética , Estrutura Molecular , Relação Estrutura-Atividade , Células U937RESUMO
The search for new drugs requires a deep understanding of the molecular basis of drug action, being necessary the elucidation of the mechanism of action with the understanding of the relationship between structure and activity. In the present study, we evaluated the pro-apoptotic activity of 7,8-dihydroxy-4-methylcoumarin (DHMC) and its underlying mechanisms in human leukemic cells. Here, we present evidence that DHMC induced selective and concentration-dependent apoptosis in human leukemic cells. The pro-apoptotic effect of DHMC was mediated by activation of the JNKs and inhibition of the ERK1/2 and PI3K/Akt pathways, with no participation of the p38 cascade after 24h of treatment. Indeed, down-regulation of the proto-oncogene c-myc as well as induction of the cell cycle inhibitor p21(WAF1/CIP1) through a p53 independent mechanism were observed in U-937 cells. These findings suggest that DHCM may have a potential therapeutic role in the future treatment of hematological malignancies.