Chemical characterization, antioxidant and photoprotective activity of extracts from Mimosa setosa Benth var. paludosa (Fabaceae).

Mimosa setosa Benth var. paludosa, popularly known as arranha-gato, pom-pom, jurema-branca, or maricá-peludo, is widely used both for the regeneration of degraded areas and in traditional medicine practices, particularly in the form of leaf infusions to promote sleep. This species, like others of its genus, produces bioactive compounds derived from secondary metabolism that may act in the prevention of diseases associated with oxidative stress and damage caused by ultraviolet radiation. This study investigated the antioxidant and photoprotective potential, as well as performed the phytochemical screening of crude leaf and root extracts of M. setosa. The antioxidant activity was evaluated in vitro using the DPPH and ABTS assays, while the photoprotective action was assessed through in vitro tests. Total phenolic and flavonoid contents were determined using the Folin-Ciocalteu method. Phytochemical screening was carried out by thin-layer chromatography (TLC), employing silica as the stationary phase and suitable solvent systems as the mobile phase. The results revealed the presence of phenolic compounds, flavonoids, terpenes, saponins, and steroids in the leaf extracts. The antioxidant capacity of the crude extracts was expressed as IC50, with values of 6.72 ± 0.71 μg/mL for leaves and 13.17 ± 3.75 μg/mL for roots using the DPPH method, and 60.29 ± 0.50 μg/mL for leaves and 36.24 ± 0.48 μg/mL for roots using the ABTS method. Total phenolic contents were 380.16 ± 17.78 mg GAE/g for leaves and 182.33 ± 3.78 mg GAE/g for roots, whereas total flavonoid contents were 72.22 ± 2.62 mg QE/g for leaves and 182.33 ± 3.78 mg QE/g for roots. The extracts did not exhibit significant photoprotective activity, with SPF values ranging from 0.072 to 0.91 mg/mL for leaves and from 0.012 to 0.035 mg/mL for roots, falling below the minimum threshold established by ANVISA for photoprotective efficacy. These findings indicate that the crude extracts of Mimosa setosa possess antioxidant activity, partly attributed to their high flavonoid and phenolic contents; however, the secondary metabolites present do not confer significant photoprotective effects.