INFLUENCE OF SOLVENTS IN OBTAINING BLACK QUINOA EXTRACTS: ANTIOXIDANT CAPACITY AND POTENTIAL USE IN THE SYNTHESIS OF NANOPARTICLES

Abstract

The study evaluated the extraction of bioactive compounds from black quinoa by sonication with three different solvents: 96º ethanol (BCQ1), ethanol:water 1:1 (BCQ2) and ultrapure water (BCQ3). The extracts showed variations in the composition of the extracted compounds, suggesting that the solvent used influences their solubilization. The concentration of total phenols in the extracts was determined by the Folin-Ciocalteu assay, obtaining values of 51.677 µg/mL for BCQ1, 47.689 µg/mL for BCQ2 and 57.187 µg/mL for BCQ3. No significant differences were observed between solvents (p > 0.05), suggesting that the choice of solvent does not drastically affect the extraction of total phenols. Regarding antioxidant capacity, the DPPH method was used, and it was found that BCQ2 extract, with the ethanol:water mixture, presented the highest antioxidant capacity, reaching 44,152 µmol TE/L. BCQ3 showed an antioxidant capacity of 31.152 µmol TE/L, whereas BCQ1 reached 0.939 µmol TE/L. These results indicate that the combination of ethanol and water optimizes the extraction of phenolic compounds and flavonoids with high free radical neutralization capacity. In addition, the synthesis of silver nanoparticles was evaluated using the extracts, observing a higher efficiency in BCQ2, which showed an absorption peak at 410 nm, indicating the formation of silver nanoparticles. In general, sonication at 25°C for 10 min with the ethanol:water mixture favored the extraction of bioactive compounds and the generation of nanoparticles with potential technological applications.