ABSTRACT
Manganese (Mn) is an essential element for human health. However, at high concentrations Mn may be neurotoxic. Mn accumulates in astrocytes, affecting their redox status. In view of the high antioxidant and anti-inflammatory properties of the exotic Brazilian fruit açaí (Euterpe oleracea Mart.), its methanolic extract was obtained by solid-phase extraction (SPE). This açaí extract showed considerable anthocyanins content and direct antioxidant capacity. The açaí extract scavenged 2,2-diphenyl-1-picrylhydrazyl radicals (DPPHâ¢) with an EC50 of 19.1 ppm, showing higher antioxidant activity compared to butylated hydroxytoluene (BHT), but lower than ascorbic acid and quercetin. This obtained açaí extract also attenuated Mn-induced oxidative stress in primary cultured astrocytes. Specifically, the açaí extract at an optimal and nutritionally relevant concentration of 0.1 µg/ml prevented Mn-induced oxidative stress by (1) restoring GSH/GSSG ratio and net glutamate uptake, (2) protecting astrocytic membranes from lipid peroxidation, and (3) decreasing Mn-induced expression of erythroid 2-related factor (Nrf2) protein. A larger quantity of açaí extract exacerbated the effects of Mn on these parameters except with respect to lipid peroxidation assessed by means of F2-isoprostanes. These studies indicate that at nutritionally relevant concentration, anthocyanins obtained from açaí protect astrocytes against Mn neurotoxicity, but at high concentrations, the "pro-oxidant" effects of its constituents likely prevail. Future studies may be profitably directed at potential protective effects of açaí anthocyanins in nutraceutical formulations.
Subject(s)
Arecaceae , Astrocytes , Dietary Supplements , Manganese , Neuroprotective Agents , Oxidative Stress , Plant Extracts , Animals , Rats , Animals, Newborn , Anthocyanins/adverse effects , Anthocyanins/analysis , Anthocyanins/metabolism , Arecaceae/chemistry , Astrocytes/cytology , Astrocytes/drug effects , Astrocytes/metabolism , Biological Transport/drug effects , Brazil , Cells, Cultured , Cerebral Cortex/cytology , Cerebral Cortex/drug effects , Cerebral Cortex/metabolism , Dietary Supplements/adverse effects , Dietary Supplements/analysis , Fruit/chemistry , Gene Expression Regulation/drug effects , Glutamic Acid/metabolism , Manganese/adverse effects , Manganese/chemistry , Manganese Poisoning/diet therapy , Manganese Poisoning/prevention & control , Nerve Tissue Proteins/biosynthesis , Nerve Tissue Proteins/metabolism , Neuroprotective Agents/adverse effects , Neuroprotective Agents/analysis , Neuroprotective Agents/chemistry , Neuroprotective Agents/metabolism , Oxidative Stress/drug effects , Plant Extracts/adverse effects , Plant Extracts/chemistry , Plant Extracts/metabolism , Rats, Sprague-Dawley , NF-E2-Related Factor 2/biosynthesis , NF-E2-Related Factor 2/metabolismABSTRACT
Biological assays that have been performed on different types of Brazilian propolis have shown that type 6 propolis (G6) has a strong antimicrobial activity and a low flavonoid content. This study aimed to evaluate the correlation between the phenolic composition and the biological activities displayed by propolis G6 from the state of Bahia and green propolis, also known as type 12 (G12). The values of the flavonoids and the total phenolics in propolis G6 were different than those in propolis G12. Although the G12 variety presented greater antioxidant activity, propolis G6 proved to have greater antimicrobial and cytotoxic activities. The results showed that the phenolic compounds may not be the only compounds responsible for the biological activity. More detailed studies of the chemical composition and an assessment of the biological activity are required to establish the quality of propolis.
Ensaios biológicos realizados com diferentes tipos de própolis brasileira têm mostrado que a própolis do tipo 6 (G6) tem forte atividade antimicrobiana e menor teor de flavonóides. Este trabalho teve como objetivo avaliar a correlação entre a composição fenólica e atividades biológicas apresentadas pela própolis G6, do Estado da Bahia, e a própolis verde, do tipo 12 (G12). Os teores de flavonóides e fenólicos totais na própolis G6 foram diferentes dos teores da própolis G12. Apesar da G12 apresentar maior atividade antioxidante, a própolis G6 apresenta maior atividade antimicrobiana e citotóxica. Os resultados mostraram que os compostos fenólicos não são os únicos compostos responsáveis pela atividade biológica da própolis. Estudos mais específicos da composição química, em adição à avaliação das atividades biológicas, são requeridos para determinar a qualidade da própolis.
