Aplicação de planejamentos estatísticos para a extração dos compostos fenólicos obtidos a partir das folhas de aranto (Kalanchoe crenata) e avaliação do potencial antioxidante e antimicrobiano

Abstract

Different Kalanchoe species are used as medicinal plants in different cultures, containing various phenolic compounds such as flavonoids and phenolic acids with antioxidant potential. Therefore, the aim was to optimize the extraction process of phenolic compounds from cranberry (Kalanchoe crenata) using a central substance scheduling system and to evaluate the antioxidant and antibacterial potential of the extracts obtained. A 24 factorial design with variations in sonication time, initial pH, cranberry concentration, and water:alcohol ratio was used for variable selection. Thus, the variables that have a significant effect on the extraction of phenolic compounds were included in the optimization. The obtained extracts were used to determine the phenolic compounds and antioxidant potential against DPPH• and ABTS•+ radicals, as well as chelation with Cu2+ and Fe2+. The phenolic compound contents obtained ranged from 55 to 460 mg gallic acid equivalents/mg crude extract, with a significant increase after optimization, ranging from 538.33 to 1473.89 mg.EAG.mg-1. After the factorial design 24 analysis, it was found that the variables sonication time and concentration of aranto were significant for the extraction of phenolic compounds. Moreover, the extracts obtained showed antioxidant potential against DPPH• and ABTS•+ radicals and chelation with Cu2+ and Fe2+, which increased after optimization. Regarding antibacterial potential, the extract showed a minimum inhibitory concentration (MIC) of 2 mg.mL-1 against E. coli, and against S. typhimurium and S. aureus bacteria, the MIC was 1 mg.mL-1. The crude extract studied inhibited the growth of Candida tropicalis and Candida fomata. Finally, the extracts of Kalanchoe crenata showed significant antioxidant and antibacterial potential, which could indicate a possible application in food and pharmaceutical formulations.