ABSTRACT Amburana cearensis (Allemão) A.C. Sm., Fabaceae, has been widely studied for its medicinal activities. Many neurodegenerative disorders are caused by oxidative stress, mitochondrial dysfunction, excitotoxicity induced by glutamate and ultimately cell death. This study describes the chemical profile of the ethanolic, hexane, dichloromethane, and ethyl acetate extracts obtained from seeds of A. cearensis. The objective of this study was to investigate the chemical profile of extracts obtained from seeds of A. cearensis, as well as their cytotoxicity and neuroprotective effects in cultures of neural PC12 cells. Metabolite profile was performed by GC–MS. PC12 cells were treated with increasing concentrations of the extracts (0.01–2000 µg/ml) and the cell viability was analyzed after 24 and 72 h using an MTT test. For the excitotoxicity assay, PC12 cells were pre-treated with glutamate (1 mM) for 6 h and treated with increasing concentrations (0.1–1000 µg/ml) of the extracts. The chromatographic analysis of the extracts detected various compounds with antioxidant properties, with the majority of peaks corresponding to the isoflavone coumarin. Only the hexane extract showed toxicity after 72 h exposure at the highest concentration (1000 µg/ml). By contrast, all extracts increased the cellular viability of PC12 cells against the toxicity caused by glutamate. Therefore, the extracts from the seeds of A. cearensis showed no toxicity and have neuroprotective potential against neuronal damage induced by glutamate, which may be related to their antioxidant properties.

ABSTRACT Prosopis juliflora is a shrub that has been used to feed animals and humans. However, a synergistic action of piperidine alkaloids has been suggested to be responsible for neurotoxic damage observed in animals. We investigated the involvement of programmed cell death (PCD) and autophagy on the mechanism of cell death induced by a total extract (TAE) of alkaloids and fraction (F32) from P. juliflora leaves composed majoritary of juliprosopine in a model of neuron/glial cell co-culture. We saw that TAE (30 µg/mL) and F32 (7.5 µg/mL) induced reduction in ATP levels and changes in mitochondrial membrane potential at 12 h exposure. Moreover, TAE and F32 induced caspase-9 activation, nuclear condensation and neuronal death at 16 h exposure. After 4 h, they induced autophagy characterized by decreases of P62 protein level, increase of LC3II expression and increase in number of GFP-LC3 cells. Interestingly, we demonstrated that inhibition of autophagy by bafilomycin and vinblastine increased the cell death induced by TAE and autophagy induced by serum deprivation and rapamycin reduced cell death induced by F32 at 24 h. These results indicate that the mechanism neural cell death induced by these alkaloids involves PCD via caspase-9 activation and autophagy, which seems to be an important protective mechanism.

Since the biological activity of [RuIII(NH3)4(catechol)]+ has never been tested, its cytotoxicity to glial cells was assayed and correlated with its redox properties. Coordinated catechol oxidizes faster than catechol in the presence of oxygen, but controlled potential electrolysis showed that its oxidation involves only one-electron. However, the oxidation of the free ligand by oxygen involves two electrons, which could generate more reactive oxygen species. Indeed, catechol was more cytotoxic than [RuIII(NH3)4(catechol)]+ complex to human glioblastoma GL-15 cells and also to rat astrocytes. [RuIII(NH3)4(catechol)]+-induced cytotoxicity was related to the generation of reactive oxygen species and [RuC1(NH3)5]2+. However, other mechanisms should be involved since antioxidant enzymes and deferoxamine only partially protected GL-15 cells