RESUMO
The purpose of this work is to investigate the protein kinase inhibitory activity of constituents from Acacia auriculiformis stem bark. Column chromatography and NMR spectroscopy were used to purify and characterize betulin from an ethyl acetate soluble fraction of acacia bark. Betulin, a known inducer of apoptosis, was screened against a panel of 16 disease-related protein kinases. Betulin was shown to inhibit Abelson murine leukemia viral oncogene homolog 1 (ABL1) kinase, casein kinase 1ε (CK1ε), glycogen synthase kinase 3α/ß (GSK-3 α/ß), Janus kinase 3 (JAK3), NIMA Related Kinase 6 (NEK6), and vascular endothelial growth factor receptor 2 kinase (VEGFR2) with activities in the micromolar range for each. The effect of betulin on the cell viability of doxorubicin-resistant K562R chronic myelogenous leukemia cells was then verified to investigate its putative use as an anti-cancer compound. Betulin was shown to modulate the mitogen-activated protein (MAP) kinase pathway, with activity similar to that of imatinib mesylate, a known ABL1 kinase inhibitor. The interaction of betulin and ABL1 was studied by molecular docking, revealing an interaction of the inhibitor with the ABL1 ATP binding pocket. Together, these data demonstrate that betulin is a multi-target inhibitor of protein kinases, an activity that can contribute to the anticancer properties of the natural compound and to potential treatments for leukemia.
Assuntos
Acacia/química , Antineoplásicos Fitogênicos/farmacologia , Regulação Leucêmica da Expressão Gênica/efeitos dos fármacos , Inibidores de Proteínas Quinases/farmacologia , Proteínas Proto-Oncogênicas c-abl/antagonistas & inibidores , Triterpenos/farmacologia , Antineoplásicos Fitogênicos/química , Antineoplásicos Fitogênicos/isolamento & purificação , Apoptose/efeitos dos fármacos , Apoptose/genética , Sítios de Ligação , Caseína Quinase 1 épsilon/antagonistas & inibidores , Caseína Quinase 1 épsilon/genética , Caseína Quinase 1 épsilon/metabolismo , Proliferação de Células/efeitos dos fármacos , Proteínas de Fusão bcr-abl/antagonistas & inibidores , Proteínas de Fusão bcr-abl/genética , Proteínas de Fusão bcr-abl/metabolismo , Quinase 3 da Glicogênio Sintase/antagonistas & inibidores , Quinase 3 da Glicogênio Sintase/genética , Quinase 3 da Glicogênio Sintase/metabolismo , Humanos , Janus Quinase 3/antagonistas & inibidores , Janus Quinase 3/genética , Janus Quinase 3/metabolismo , Células K562 , Proteína Quinase 1 Ativada por Mitógeno/antagonistas & inibidores , Proteína Quinase 1 Ativada por Mitógeno/genética , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno/antagonistas & inibidores , Proteína Quinase 3 Ativada por Mitógeno/genética , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Modelos Moleculares , Quinases Relacionadas a NIMA/antagonistas & inibidores , Quinases Relacionadas a NIMA/genética , Quinases Relacionadas a NIMA/metabolismo , Casca de Planta/química , Extratos Vegetais/química , Ligação Proteica , Conformação Proteica , Inibidores de Proteínas Quinases/química , Inibidores de Proteínas Quinases/isolamento & purificação , Proteínas Proto-Oncogênicas c-abl/química , Proteínas Proto-Oncogênicas c-abl/genética , Proteínas Proto-Oncogênicas c-abl/metabolismo , Transdução de Sinais , Triterpenos/química , Triterpenos/isolamento & purificação , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/antagonistas & inibidores , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/genética , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/metabolismoRESUMO
Gutenbergia nigritana (Benth). Oliv and Hein (Asteraceae) is a Nigerian ethnomedicinal plant which has long being used medicinally in traditional systems of medicine. The plant has diverse ethnomedicinal uses which include: The Plant is used in the Ijaw area of Niger Delta region of Nigeria to treat Malaria, convulsion, diarrhea and as a remedy for skin infection. The antibacterial study on dichloromethane extract and chromatographic fractions:dichloromethane soluble part(DC1), ethyl acetate soluble part(E1) and N-butanol soluble portions of methanolic extract were investigated using agar diffusion assay method by measuring the zone of inhibition against clinical isolates: Bacillus subtillis, Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. Extensive Chromatographic separation and preparative TLC were employed in the isolation steps. Column chromatograpy of the dichloromethane extract, gel filteration on sephadex and preparative TLC led to the isolation of two triterpenoids: Lupenol(1) and Lupenol acetate(2). The structures were elucidated by NMR spectroscopy and compared with literature. The dichloromethane extract exhibited antibacterial activity against all the test microorganisms with zones of inhibition ranging between 12-26mm. The chromatographic fraction (Fr-6) exhibited activity against E. coli, Ps. aeruginosa and S. aureus but in-active against B. subtilis, while the methanol soluble portions: dichloromethane and ethyl acetate showed weak activity while the n-butanol portion was in active. Dichloromethane extract of Gutenbergia nigritana leaves exhibited anti-bacterial activity, though the compounds isolated did not show activity, it is likely that the activity might reside in other components present in the dichloromethane extract.