Optimization study of obtaining raw extracts of arantho leaves (Kalanchoe crenata) assisted by ultrasound and evaluation of the biological potential
Natural plant products; Gram-positive bacteria; Gram-negative bacteria; Kalanchoe sp.
Different species of Kalanchoe are employed as medicinal plants in various cultures, where they contain various phenolic compounds such as flavonoids and phenolic acids with antioxidant potential. Thus, the objective was to optimize the extraction process of phenolic compounds from aranto (Kalanchoe crenata), using central compound planning and the evaluation of the antioxidant and antibacterial potential of the obtained extracts. For the selection of variables, a 24 factorial design was employed with variation in sonication time, initial pH, concentration of cranberry, and water:alcohol ratio. Thus, the variables with significant effect on the extraction of phenolic compounds were employed in the optimization. The obtained extracts were submitted to the determination of phenolic compounds and antioxidant potential against DPPH, ABTS radicals and chelation with Cu2+ and Fe2+. The levels of phenolic compounds obtained ranged from 55 to 460 mg gallic acid equivalents.mL-1, with a significant increase after optimization. The variables sonication time and concentration of aranto were significant for extraction of phenolic compounds. Furthermore, the obtained extracts showed antioxidant potential against DPPH and ABTS radical sequestration and chelating with Cu2+ and Fe2+, with an increase after optimization. Regarding the antioxidant potential, the minimum inhibitory concentrations observed were 25; 12.5; and 50 mg.mL-1 against Escherichia coli, Salmonella typhimurium, Bacillus cereus and Staphylococcus aureus, respectively. Finally, Kalanchoe crenata extracts showed significant antioxidant and antibacterial potential, which may indicate possible application in food and pharmaceutical formulations.