Phytochemical Characterization, Antioxidant, and Photoprotective Activities of Pseudobombax simplicifolium A. Robyns

Plants of the genus Pseudobombax Dugand (Malvaceae) exhibit a wide range of medicinal properties, including antioxidant, anti-inflammatory, antinociceptive, antimicrobial, and anticancer activities. This study is the first to analyze the phytochemical composition, antioxidant properties, and sun protection factor (SPF) of Pseudobombax simplicifolium. Phytochemical tests of the hydroalcoholic extracts from the stem barks (HEB) and leaves (HEL) of P. simplicifolium indicated the presence of saponins, phenolic compounds, tannins, flavonoids, alkaloids, steroids, and terpenoids. Chromatographic fractionation of the HEB and HEL resulted in isolating of the three known compounds lupeol, β-sitosterol, and lup-20(29)-en-3β-28-diol that are being reported here for the first time in this species. The extracts and fractions exhibited antioxidant activity as measured by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) (IC₅₀ = 14.85 ± 0.15 for HEB-F9), 2,2-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) (IC₅₀ = 27.47 ± 0.53 for HEB-F9), and total antioxidant capacity (TAC) (IC₅₀ = 627.43 ± 2.16 for HEB-F9) assays. Additionally, the HEB and its fractions demonstrated photoprotective activity against ultraviolet radiation, with SPF values of 25.01 at concentrations as low as 50 µg mL, exceeding the minimum SPF required by regulations. LC-MS analysis of the HEB and its fractions identified a variety of compounds phenolic, which are likely responsible for the observed activities.