RESUMO
Gliomas are responsible for more than 60% of all primary brain tumors. Glioblastoma multiforme (GBM), a grade IV tumor (WHO), is one of the most frequent and malignant gliomas. Despite two decades of advances in the discovery of new markers for GBM, the chemotherapy of choice falls to temozolomide after surgery and radiotherapy, which are not enough to increase the survival of patients to more than 15 months. It is urgent to discover new anti-glioma compounds. Many compounds derived from natural products have been used in the development of anti-tumor drugs. In this work, we have screened six low molecular weight sesquiterpene lactones, isolated from Eremanthus spp., and studied their function as anti-proliferative agents against GBM strains. We demonstrated that two of them, goyazensolide and lychnofolide, were effective in reducing cell viability, preventing the formation of anchorage-dependent colony and were able to pass through a mimetic blood-brain barrier making them candidates for glioma therapy, being more potent than temozolomide, according to in vitro assays for the cell lines tested. Proteomic analysis revealed a number of altered proteins involved in glycolytic metabolism and cellular catabolism.
Assuntos
Lactonas/farmacologia , Vernonia/metabolismo , Antineoplásicos/farmacologia , Asteraceae , Barreira Hematoencefálica/metabolismo , Neoplasias Encefálicas/metabolismo , Brasil , Hidrocarbonetos Aromáticos com Pontes/farmacologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Furanos/farmacologia , Glioblastoma/tratamento farmacológico , Glioblastoma/metabolismo , Glioma/metabolismo , Humanos , Lactonas/metabolismo , Extratos Vegetais/farmacologia , Sesquiterpenos/farmacologia , Sesterterpenos/farmacologia , Vernonia/fisiologiaRESUMO
The ethanol extract from Vernonia polyanthes leaves (EEVP) was investigated for antinociceptive and anti-inflammatory effects at the doses (p.o.) of 100, 200 and 400 mg/kg in animal models. The extract reduced the number of abdominal contortions by 16.75% and 31.44% at a dose of 200 and 400 mg/kg, respectively. The results obtained showed that EEVP exerted a significant antinociceptive effect in the two phases of formalin. The EEVP increased the reaction time on a hot plate at the doses of 100, 200 and 400 mg/kg after 90 min of treatment. The paw edema was reduced by EEVP at the doses of 100, 200 and 400 mg/kg after 4 h of application of carrageenan. Doses of 200 and 400 mg/kg, administered 4 h before the carrageenan injection, significantly reduced the exudate volume (29.25 and 45.74%, respectively) and leukocyte migration (18.19 and 27.95%, respectively). These results suggest that V. polyanthes can be an active source of substances with antinociceptive and anti-inflammatory activities.
Assuntos
Analgésicos/uso terapêutico , Anti-Inflamatórios não Esteroides/uso terapêutico , Extratos Vegetais/uso terapêutico , Folhas de Planta/metabolismo , Vernonia/metabolismo , Animais , Carragenina , Edema/tratamento farmacológico , Etanol/química , Inflamação/induzido quimicamente , Inflamação/tratamento farmacológico , Masculino , Camundongos , Dor/induzido quimicamente , Dor/tratamento farmacológico , Manejo da Dor , Medição da Dor , Ratos , Ratos WistarRESUMO
Vernonia herbacea (Vell.) Rusby, a native species from the Brazilian Cerrado, accumulates about 80% of fructans in the rhizophores, the underground reserve organs. Besides their role as reserve, fructans have been recognized as protective compounds against drought. This physiological function attributed to fructans seems consistent with the wide occurrence of these carbohydrates in the cerrado, a biome that undergoes seasonal drought. The aim of this work was to analyze fructan composition and the activities of the enzymes involved in fructan synthesis, sucrose:sucrose 1-frutosyltransferase (1-SST) and fructan:fructan 1-frutosyltransferase (1-FFT), and depolymerization, fructan 1-exohydrolase (1-FEH) in plants submitted to water suppression. The plants were divided into 3 groups receiving 3 treatments: daily watering (control), water suppression for 23 days (WS) and re-watering after 15 days (RW). Samples were taken at the beginning of the experiment (Time 0) and after 3, 7, 11, 15, 17 and 23 days of water suppression. 1-SST and 1-FFT activities increased at the beginning of the water restriction period, coinciding with a decrease in 1-FEH activity, the onset of the reduction in soil water potential and in leaf water potential. Increases in 1-FEH and invertase activities led to a high yield of reducing sugars at the 23rd day after water suppression, and together with 1-FFT, 1-FEH also seemed to act in the redistribution of fructan molecules after re-watering. The increase in reducing sugars and in the fructo-oligo:fructo-polysaccharide ratio were associated to the maintenance of rhizophore turgor. Considering that WS plants showed changes in fructan metabolism that favored water retention and absorption after re-watering, the occurrence of osmotic adjustment mechanisms is suggested, reinforcing the hypothesis of fructans as protective agents against abiotic stresses, such as drought.
Assuntos
Adaptação Fisiológica , Secas , Frutanos/metabolismo , Estruturas Vegetais/fisiologia , Estresse Fisiológico , Vernonia/metabolismo , Água/fisiologia , Osmose , Vernonia/enzimologiaRESUMO
Rhizophores of Vernonia herbacea, an Asteraceae found in the Brazilian Cerrado, store high amounts of fructans that vary in composition over the phenological cycle. Fructan 1-exohydrolase (1-FEH) activity is detectable during the sprouting phase, mainly in the proximal regions of rhizophores, of plants induced to sprout by defoliation and/or cold storage. We found an increase in 1-FEH gene expression during natural and induced sprouting and further enhancement through low-temperature treatment. Furthermore, a comparative analysis of 1-FEH gene expression in different regions of the rhizophores during the transition from dormancy to sprouting is presented. Transcripts were detected mainly in the proximal region, coinciding with high 1-FEH activity and a high concentration of free fructose. Low temperature promoted the accumulation of fructans of a low degree of polymerization (DP) and enhanced 1-FEH activity and gene expression. It is hypothesized that a set of 1-FEH proteins acts in two different ways during fructan mobilization: (1) by hydrolyzing fructo-oligosaccharides and -polysaccharides in sprouting plants (naturally or induced) for carbon supply and (2) by hydrolyzing preferably fructo-polysaccharides under low temperature to maintain the oligosaccharide pool for plant cold acclimation.
Assuntos
Glicosídeo Hidrolases/química , Raízes de Plantas/enzimologia , Vernonia/enzimologia , Brasil , Temperatura Baixa , Frutanos/biossíntese , Frutanos/química , Regulação da Expressão Gênica de Plantas , Glicosídeo Hidrolases/genética , Glicosídeo Hidrolases/metabolismo , Oligossacarídeos/genética , Proteínas de Plantas/química , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raízes de Plantas/genética , Raízes de Plantas/crescimento & desenvolvimento , Vernonia/química , Vernonia/genética , Vernonia/metabolismoRESUMO
Variations in the inulin contents have been detected in rhizophores of Vernonia herbacea during the phenological cycle. These variations indicate the occurrence of active inulin synthesis and depolymerization throughout the cycle and a role for this carbohydrate as a reserve compound. 1-Fructan exohydrolase (1-FEH) is the enzyme responsible for inulin depolymerization, and its activity has been detected in rhizophores of sprouting plants. Defoliation and low temperature are enhancer conditions of this 1-FEH activity. The aim of the present work was the cloning of this enzyme. Rhizophores were collected from plants induced to sprout, followed by storage at 5 degrees C. A full length 1-FEH cDNA sequence was obtained by PCR and inverse PCR techniques, and expressed in Pichia pastoris. Cold storage enhances FEH gene expression. Vh1-FEH was shown to be a functional 1-FEH, hydrolyzing predominantly beta-2,1 linkages, sharing high identity with chicory FEH sequences, and its activity was inhibited by 81% in the presence of 10 mM sucrose. In V. herbacea, low temperature and sucrose play a role in the control of fructan degradation. This is the first study concerning the cloning and functional analysis of a 1-FEH cDNA of a native species from the Brazilian Cerrado. Results will contribute to understanding the role of fructans in the establishment of a very successful fructan flora of the Brazilian Cerrado, subjected to water limitation and low temperature during winter.