Potencial de metabólitos da acerola (<i>Malpighia emarginata</i>) como antioxidantes em diferentes sistemas oxidativos mediados por radicais livres

Abstract

Potential of acerola (Malpighia emarginata) metabolites as antioxidants in different oxidative systems mediated by free radicals Natural antioxidants extracted from plants show potential to replace synthetic ones. However, publications that both evaluates the activities of these compounds in in vivo systems and elucidate the chemical characteristics of these substances are scarce and often resorts to techniques that do not necessarily reflect the antioxidant activity in different systems. Acerola fruits have considerable concentrations of antioxidant compounds, so in this study the extraction of natural compounds from green and ripe acerola fruits was optimized and different methods for in vivo antioxidant activity evaluation using Saccharomyces cerevisiae as model microorganism were performed. Surface response methodology was applied to identify effects of ethanol concentration and temperature during the extraction of antioxidants compounds, using as response the reducing power and the sequestering activity of radicals ABTS and DPPH. Two strains of S. cerevisiae were used to evaluate the in vivo antioxidant activity: wild Type (WT) and the genetically modified (erg6Δ), which had difference in the presence of ergosterol (ERG) and zymosterol (ZYM). These two sterols were analyzed by molecular modelling to evaluate their possible antioxidant activity. Effects of green and ripe acerola fruits extracts, synthetic antioxidants Butylated hydroxyanisole (BHA), Butylated hydroxytoluene (BHT) and ascorbic acid were evaluated on the oxidative stress caused in the cells by different chemical reagents, cell culturability, cell membrane oxidation level and intracellular oxidation. Finally, the effect of the microencapsulation process by spray drying on the chemical composition of the acerola extracts was evaluated. Through the surface response methodology it was possible to determine the optimal conditions to produce acerola extracts rich in phenolic compounds and ascorbic acid. The extracts of acerola showed a high or equal antioxidant activity in the studies with S. cerevisiae cells, especially when compared to the synthetic antioxidants BHT and ascorbic acid. It has still been proven in in vivo experiments that at the presence of BHA in all concentrations, besides to do not prevent oxidation, proved to be a deleterious substance to cells, mainly in the intracellular studies. Through molecular modeling it was possible to predict an antioxidant activity for ERG and, in a lesser degree, for ZYM by the mechanism of electron transfer followed by proton donation. It was possible to obtain a microencapsulated powder from green acerola extract as a promising product for future food applications. The same conditions applied to mature acerola fruit extracts showed undesirable effect on reduction power and scavenging capacity. The study concludes that it is possible to obtain extracts rich in antioxidants compounds from green and ripe acerola fruits under optimized conditions. S. cerevisiae can be used as a model microorganism for in...

A Greener and Faster Approach for Determination of Phenolic Compounds by Smartphone-Based Colorimetry

“…The experiment number 11 (extraction with 17% (v/v) ethanol, at 38 °C for 50 min) presented the highest efficiency of extraction of phenolic compounds. This condition is quite different from the one recommended in the literature for extraction of polyphenols with convective heating (extraction with 14.5% (v/v) ethanol, at 55.6 °C for 50 min) [17] and provided a TPC value 39% higher, indicating the better efficiency of the microwave-assisted extraction.…”