Avaliação do potencial terapêutico do extrato aquoso de Peumus boldus (boldo) frente à toxicidade induzida por ferro e cobre em diferentes modelos experimentais

Abstract

The transition metals iron (Fe2+) and copper (Cu2+) are vital trace elements due to oxi-reducing properties. However, the free Fe2+ and Cu2+ accumulation can lead to oxidative stress (OS), by catalisis the Fenton reaction. The OS can lead to damage in biological macromolecules and is involved in the etiology of various pathologies, especially in liver and central nervous system (CNS), where Fe2+ and Cu2+ accumulates. Therefore, there is a growing interest for agents able to minimize or block the toxic effects of Fe2+and Cu2+. The Peumus boldus extract, used for the treatment of liver disorders, has shown antioxidant properties in different in vivo and in vitro experimental models, as well as boldine, the main alkaloid isolated from the plant. However, the pharmacological properties of P. boldus against Fe2+- induced hepatotoxicity, and Cu2+-induced toxicity, remains unexplored. Likewise, there is no data on the possible beneficial effects of P. boldus on the Cu2+ toxicity using Drosophila melanogaster as an experimental model, a specie widely used due to the fact of sharing well conserved genes with mammals such as those related to Cu2+ homeostasis. Thus, the main objective of this study was to evaluate the possible protective effect of P. boldus and boldine against Fe2+-induced hepatic oxidative damage in vitro using rat liver mitochondria, and the effect of P. boldus supplementation on molecular alterations induced by exposure to Cu2+ in D. melanogaster, in vivo and ex vivo. The results show that P.boldus aqueous extract was more efficient than boldine in decreasing the lipid peroxidation, the reactive oxygen species (ROS) production, and swelling induced by Fe2+ in hepatic mitochondria of rats. The antioxidant activity assays in non-biological systems showed that P. boldus was effective in chelating Fe2+, whereas boldine presented higher reducing power than P. boldus. Cu2+ impaired in the negative geotaxis performance (i.e. motor climbing capability), but P. boldus co-exposure was effective to protect against the Cu2+-induced toxicity. Acetylcholinesterase (AChE) and glutathione S-transferase (GST) activity decreased significantly in D. melanogaster after Cu2+ exposure. P. boldus co-treatment restored enzyme activities to control levels. In addition, Cu2+ exposure increased the mRNA levels of the enzymes, superoxide dismutase (Sod1), catalase (Cat), thioredoxin reductase (TrxR1), nuclear factor erythroid 2– related factor 2 (Nrf2), acetylcholinesterase (Ace) and Cu2+ transporters, P-type ATPase (Atp7A) and copper uptake protein 1 (Ctr1A). These alterations were restored to control levels by co-treatment with P.boldus. These findings suggest that P. boldus could be considered a promising plant in modulation of toxicity induced by an excess of Fe2+ and Cu2+. P.boldus and boldine can have antioxidant properties in protection against hepatic diseases associated with Fe-free and OS. In summary, these results contribute to the advancement of the investigations of agents that may in the assist therapy of intoxications or autosomal diseases linked to an excess of Fe2+ and Cu2+.