Analysis of the flavonoid compounds and antioxidant capacity of the leaf extract obtained from Arrabidaea chica cultivated in Southern Brazil

There is a growing interest in natural antioxidants present in medicinal and dietary plants that might help attenuate oxidative damage. To identify antioxidant from herbs, we have investigated the antioxidant potential from Arrabidaea chica (HBK) Verlot). This plant has been used as an anti-inflammatory and astringent agent as well as remedies for intestinal colic, diarrhea, leucorrhoea, anemia and leukemia. This study aimed to develop a high-performance liquid chromatographic (HPLC) method for the validation and quantification of scutellarein and apigenin obtained from the extract of the leaves of Arrabidaea chica and to analyze the antioxidant activity of the crude extract using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method, β-carotene bleaching test, and total reactive antioxidant potential (TRAP) test. The validation of the HPLC method using apigenin and scutellarein as external standards showed that the method was precise and accurate and afforded good linearity. The method allowed the identification and quantification of apigenin (112.04 ± 0.52 µg/mL) and scutellarein (818.60 ± 3.26 µg/mL) in the extract of A. chica. The crude extract quenched DPPH free radicals in a dose-dependent manner and the IC₅₀ of the extract was 13.51 µg/mL. The β-carotene bleaching test showed that the addition of the A. chica extract in different concentrations (200 and 500 µg/mL) prevented the bleaching of β-carotene at different degrees (51.2 ± 3.38 and 94 ± 4.61%). The TRAP test showed dose-dependent correlation between the increasing concentrations of A. chica extract (0.1, 0.5 and 1.0 µg/mL) and the TRAP values obtained by trolox (hydro-soluble vitamin E) that were 0.4738 ± 0.0466, 1.981 ± 0.1603 and 6.877 ± 1.445µM Trolox respectively. The results of these tests showed that the extract of A. chica had a significant antioxidant activity, which could be attributed to the presence of the mixture of flavonoids and others compounds in the plant extract.