Caracterização química e avaliação da atividade fotoprotetora das cascas de Pseudobombax Simplicifolium A. Robyns (Malvaceae s.l.)

Abstract

Plants of the genus Pseudobombax Dugand (Malvaceae sensu lato) are known in literature for their antioxidant, anti-inflammatory, antinociceptive, and antimicrobial activities, and for the presence of flavonoids, alkaloids, tannins, saponins, steroids, xanthones, and chalcones. The species Pseudobombax simplicifolium A. Robyns, known as Embiratanha and Imbiruçu, is popularly used to combat anemia, inflammation, and to improve kidney function; however, studies on its chemical composition and biological activity are quite incipient. This species is being studied by our research group, where its antioxidant potential and the presence of phenolic compounds have already been identified. In this sense, this research aimed to continue the phytochemical study and investigate the photoprotective activity of P. simplicifolium. The hydroalcoholic extract of P. simplicifolium (EHC-PS) and the polar fractions (EHC-F2, EHC-F3, EHC-F4, EHC-F5 and EHC-F6) were submitted to quantitative analysis by UV-Vis spectrophotometer to determine the contents of flavonoids and total phenols, and the qualitative phytochemical analysis by Liquid Chromatography coupled to Electrospray Ionization Mass Spectrometry with Time of Fly Analyzer (CL-EM-ESI-TOF). The evaluation of the photoprotective activity was performed by in vitro spectrophotometry, where the Sun Protection Factor (SPF) of P. simplicifolium extracts and fractions was determined. From the data obtained in the quantitative analysis it was determined the values ranging from 8.778 ± 0.07 mg QE/g to 13.199 ± 0.30 mg QE/g for the content of total flavonoids and total phenols showed contents ranging from 323.477 ± 19.30 mg GAE/g to 647.942 ± 12.81 mg GAE/g. These data were corroborated in the CL-EM-ESI-TOF analysis that showed the presence of phenolic compounds and flavonoids, allowing the identification of the following compounds: caffeoylquinic acid, quercetin, rutin, catechin, 3'-methoxyapigenin, luteolin-7-b-O-neohesperidoside, nicotiflorin, and others. In the in vitro SPF determination study, it was observed that the EHC-PS at concentrations of 100 µg/mL, 500 µg/mL and 1000 µg/mL, and all fractions (EHC-F2, EHC-F3, EHC-F4, EHC-F5 and EHC-F6) exhibited photoprotective potential against ultraviolet radiation, exceeding the minimum protection factor established in the legislation. The extract and fractions presented a significant sun protection factor that can be justified due to the presence of phenolic and flavonoid compounds. In addition, this is the first study that reports the identification of chemical constituents for the genus Pseudobombax, contributing to the chemotaxonomy of this genus and demonstrates the importance of the dereplication method in the identification of known compounds.