RESUMO
Two isoforms of a ligand-activated nuclear receptor, RORγ and RORγT, have been implicated in various physiological functions, including energy metabolism, circadian rhythm and immune system development. Using a stably transfected reporter cell line, we screened two chemical libraries and identified three cardenolides (natural, plant-derived pesticides) as activators of RORγ-dependent transcription. These compounds increased G6PC and NPAS2 expression in HepG2 cells, accompanied by increased occupancy of RORγ within the promoters of these genes. Further, strophanthidin, digoxigenin and dihydroouabain upregulated IL17A and IL17F expression and enhanced IL17 secretion in Th17 human lymphocytes. Molecular docking analyses of these compounds to the RORγ LBD showed favorable docking scores, suggesting that cardenolides may act as agonists of the receptor. Thus, our results provide new chemical structures for further development of RORγ-selective modulators with virtual therapeutic potential.
Assuntos
Digoxigenina/toxicidade , Hepatócitos/efeitos dos fármacos , Membro 3 do Grupo F da Subfamília 1 de Receptores Nucleares/agonistas , Ouabaína/análogos & derivados , Estrofantidina/toxicidade , Células Th17/efeitos dos fármacos , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Sítios de Ligação , Digoxigenina/química , Relação Dose-Resposta a Droga , Glucose-6-Fosfatase/genética , Glucose-6-Fosfatase/metabolismo , Células Hep G2 , Hepatócitos/metabolismo , Humanos , Interleucina-17/genética , Interleucina-17/metabolismo , Simulação de Acoplamento Molecular , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Membro 3 do Grupo F da Subfamília 1 de Receptores Nucleares/química , Membro 3 do Grupo F da Subfamília 1 de Receptores Nucleares/genética , Membro 3 do Grupo F da Subfamília 1 de Receptores Nucleares/metabolismo , Ouabaína/química , Ouabaína/toxicidade , Regiões Promotoras Genéticas , Ligação Proteica , Conformação Proteica , Transdução de Sinais/efeitos dos fármacos , Estrofantidina/química , Relação Estrutura-Atividade , Células Th17/metabolismo , Fatores de Tempo , Transcrição Gênica/efeitos dos fármacos , Ativação Transcricional/efeitos dos fármacosRESUMO
INTRODUCTION: The commonly used cardiac glycoside, digoxin (DIG), has a narrow therapeutic window. Although some investigations were made to counteract its toxic effects, no alternate phytochemical is available till date that is more potent and safer than DIG. AIMS: Our main aim was to isolate a novel cardenolide from the seeds of Trigonella foenum graceium and to evaluate its relative potential in comparison to that of DIG. EXPERIMENTAL DESIGN: In one experiment effects of the isolated compound at 2.5, 5.0, and 10 mg/kg (p.o.) were evaluated in isoproterenol (ISO)-induced cardiovascular problems in rats. As the test drug (TDR) reversed most of the ISO-induced changes, it was subjected to the phytochemical analyses and was identified as digoxigenin-3-O-rutin. In another experiment effects of DIG and rutin (Rtn) were compared with those of TDR or DIG alone. The hydroxyl radical scavenging activity was also measured by electron spin resonance (EPR). RESULTS: digoxigenin-3-O-rutin at 10 mg/kg markedly reduced the ISO-induced increase in cardiac lipid peroxidation and in the levels of serum creatinine phosphokinase-MB, glutamate oxaloacetate transaminase, glutamate pyruvate transaminase, lactate dehydrogenase, and creatinine. It also reversed the ISO-induced changes in the cardiac histomorphology. Interestingly TDR appeared to be more effective than DIG alone or DIG and Rtn in combination. CONCLUSION: The newly isolated digoxigenin-3-O-rutin appears to be more potent and safe than digoxin. Its higher efficacy could be due to its structural specificity and might have been mediated through its better free radical scavenging action.