Arrabidaea chica(Humb. & Bonpl.) Verlot: Identificação de compostos bioativos e avaliação do potencial antioxidante por métodois químicos (in vitro)

Abstract

Arrabidaea chica is a medicinal plant from the Bignoniaceae family, which occurs in tropicalAmerica and it is widely distributed in the Brazilian Amazonia. This plant can be seen as apromising source of bioactive compounds, such as phenolic compounds and carotenoids,which are secondary plant metabolites that can be used to delay oxidative damage in bothfood and biological systems. In this study, the composition of carotenoids and phenoliccompounds of A. chica leaves were identified and quantified by HPLC-DAD-MS/MS, inaddition to the ascorbic acid content. The main phenolic compounds identified werescutellarin and scutellarein (aglycone); while lutein, β-carotene and α-carotene were the maincarotenoids. Regarding the in vitro antioxidant capacity, the hydromethanolic extract of A.chica leaves was characterized as an efficient ABTS radical scavenger, in addition to protecttryptophan against oxidation by singlet oxygen in a concentration-dependent manner (IC 50 =177 μg/mL). These results stimulated the next study to further investigate the antioxidantpotential of extracts of A. chica, obtained through ultrasound-assisted extraction, using“green” solvents, against reactive oxygen (ROS) and nitrogen (RNS) species of physiologicaland food relevance. The antioxidant capacity of three extracts of A. chica leaves obtained withsolvents of different polarities (water, ethanol and ethanol/water (1:1, v/v) were tested againstsuperoxide anion radical (O 2 •- ), hydrogen peroxide (H 2 O 2 ), hypochlorous acid (HOCl), theperoxynitrite radical (ONOO−), the oxigênio singleto 1 O 2 and peroxyl radical (ROO • ). The A.chica extract prepared with ethanol/water presented the highest phenolic contents (11.80 mg/gextract), being scutelarein (flavone) the major compound (57%), while ethanol and wateralone were less efficient resulting in changes in the individual profile of phenolic compounds,highlighted by the absence of scutelarein and by the high levels of phenolic acids. All extractswere able to scavenge the tested ROS/RNS in a concentration-dependent manner with lowIC 50 values, being the extract obtained with ethanol/water the most effective for all theROS/RNS (IC 50 from 0.34 to 35.66 μg/mL). Regarding the antioxidant capacity against ROO • ,all the extracts showed the same antioxidant behavior, with scavenging efficiency about fivetimes higher than Trolox. Therefore, A. chica leaves proved to be a promising source ofbioactive compounds with high antioxidant properties to be used as natural antioxidants to inhibit oxidative damage in both food and physiological systems.