ABSTRACT
Background: A large number of chemical compounds exert their antioxidant effects by activation of key transcriptional regulatory mechanisms, such as the transcription factor Nrf2. The aim of this study was to evaluate the activation of the Keap1-Nrf2 pathway by both the n-butanol extract obtained from the inner bark of Tabebuia rosea (Bertol) DC and specioside isolated from this extract. Methods: The antioxidant activity of the extract and specioside isolated from the inner bark of T. rosea were evaluated using the oxygen radical absorbance capacity (ORAC) and the 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity (DPPH) techniques, whereas their effects on the viability of HepG2 cells was determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. The effects of the compound and the extract on activating the Keap1-Nrf2 pathway were evaluated using a Nrf2 Transcription Factor Assay kit. Induction of the Nrf2-mediated antioxidant response genes HMOX-1 and NQO1 was evaluated by real-time PCR. The protective effects against H 2O 2-induced oxidative stress in HepG2 cells was determined as the percent protection using the MTT method. Results: Both the n-butanol extract and specioside exhibited activity at low concentrations without affecting cellular viability, since the cell viability was greater than 80% after 24 hours of exposure at each tested concentration. In addition, Nrf2 dissociated from Keap1 after treatment with the n-butanol extract at a concentration of 0.25 µg/mL after 4 hours of exposure. An increase in the Nrf2 level in the cytoplasm after 4 hours of exposure to 2 µM specioside was observed. Nrf2 levels stabilized in the nucleus 12 hours after stimulation with both specioside and the extract. After 6 hours of stimulation, both the extract and specioside induced the expression of HMOX-1 and NQO1. Conclusion: The n-butanol extract from the inner bark of T. rosea and specioside produced protective effects against H 2O 2-induced oxidative stress in HepG2 cells.
Subject(s)
NF-E2-Related Factor 2 , Tabebuia , 1-Butanol , Iridoid Glucosides , Kelch-Like ECH-Associated Protein 1/metabolism , NF-E2-Related Factor 2/metabolism , Plant Bark , Plant Extracts/pharmacologyABSTRACT
Infectious diseases are a worldwide public health problem. There is growing research in the field of new plant-based drugs for treating such diseases. Our objective was to perform a systematic literature review to evaluate the anti-infectious activity (antibacterial, antifungal, antiviral and antiparasitic) attributed to plants of the Tabebuia (Bignoniaceae) genus. We conducted a search for the period of 2000-2013 in ScienceDirect, Scopus, PubMed, Embase, Napralert and SciELO databases using the following MeSH terms: Tabebuia, biological activity, bioactive compounds, chemical compounds, diseases, traditional medicine, tropical infections, infections and treatment. We found ethnobotanical and experimental (in vitro) evidence supporting the use of Tabebuia species for treating infectious diseases. In addition, the compounds responsible for their antimicrobial activity have been isolated, and their structures have been elucidated, emphasizing among them naphthoquinones such as lapachol. Natural products isolated from Tabebuia plants may be an alternative for developing new anti-infectious agents.
Dada la importancia de las enfermedades infecciosas como problema de salud pública a nivel mundial y la búsqueda de nuevos medicamentos basados en plantas para tratar dichas enfermedades; se realizó una revisión sistemática de literatura con el fin de evaluar la actividad anti-infecciosa (antibacteriana, antifúngica, antiviral y antiparasitaria) reportada en plantas pertenecientes al género Tabebuia (Bignoniaceae). Las bases de datos fueron: ScienceDirect, Scopus, Pubmed, Embase y Napralert, SciELO, durante 2000 - 2013. Se utilizaron términos en MeSH como: Tabebuia, biological activity, bioactive compounds, chemical compounds, diseases, traditional medicine, tropical infections, infections and treatment. Existe evidencia tanto etnobotánica como experimental (in vitro) que soporta el uso de especies del género Tabebuia en el tratamiento de enfermedades infecciosas. Adicionalmente, se encontró reportado y se esclareció estructuralmente los compuestos responsables de la actividad antimicrobiana, donde se destacan naftoquinonas como el lapachol. Se concluye a partir de la revisión que los productos naturales aislados de las plantas del género Tabebuia podrían considerarse alternativas para el desarrollo de nuevos agentes anti-infecciosos.
Dada a importância das doenças infecciosas como problema de saúde pública a nível mundial e a procura crescente de novos medicamentos baseados em plantas para tratar tais doenças, realiza se uma pesquisa sistematizada da literatura com o fim de avaliar a atividade anti-infecciosa (antibacteriana, antifúngica, antiviral y antiparasitária) reportada em plantas pertenecientes ao género Tabebuia (Bignoniaceae). Foi realizada uma pesquisa nas bases de dados ScienceDirect, Scopus, Pubmed, Embase y Napralert, assim como em SciELO, durante o período 2000 - 2013, empregando os términos MeSH: Tabebuia, biological activity, bioactive compounds, chemical compounds, diseases, traditional medicine, tropical infections, infections and treatment. Existe evidencia tanto etnobotánica como experimental (in vitro) que suporta o uso das espécies do género Tabebuia no tratamento das doenças infecciosas e adicionalmente, há sido isolado e identificado estruturalmente os compostos responsáveis da sua atividade antimicrobiana, donde se destacam as naftoquinonas como o lapachol. Os produtos naturais isolados de plantas do género Tabebuia poderiam considerar se como uma alternativa para o desarrolho de novos agentes anti-infecciosos.