Estudo fitoquímico e avaliação biológica das folhas de Aeschynomene americana (Fabaceae)

Abstract

Several species from the Cerrado biome are widely used in traditional medicine due to their high therapeutic potential. The genus Aeschynomene, belonging to the Fabaceae family, comprises approximately 727 genera and 19,325 species, many of which have already been associated with biological activities such as cytotoxic, antitumor, and insecticidal effects. However, to date, no phytochemical studies or biological evaluations have been reported for Aeschynomene americana. In this context, the present work provides the first investigation of the chemical constituents of the leaves, as well as their biological evaluation. The ethanolic extract of the leaves was obtained by maceration and subjected to liquid–liquid partitioning with solvents in increasing order of polarity. The ethyl acetate fraction, after successive column chromatographies, yielded pheophytin A (I), whose structure was elucidated by one- dimensional (1H) and two-dimensional (HSQC and HMBC) NMR spectroscopy. From the hexane fraction, the phytosterols β-sitosterol (II), stigmasterol (III), and campesterol (IV) were identified, while from the methanolic fraction, the flavonoid kaempferol-3-O-rutinoside (V) was isolated and identified. The antibacterial activity of the extracts and fractions was assessed using the broth microdilution method, showing no inhibitory effect (MIC > 1000 μg·mL−1 and MBC > 1000 μg·mL−1) at the tested concentrations. On the other hand, cytotoxicity assays against tumor cell lines demonstrated selectivity, with high SI values for PC3 (SI = 3.01) and HL60 (SI = 5.27). The ethanolic extract also showed good selectivity for SNB-19 (SI = 3.65). In the toxicity test against Artemia salina, the ethanolic extract and the hexane and methanol fractions presented LD50 values below 1000 μg·mL−1, whereas the ethyl acetate fraction showed an LD50 above 1000 μg·mL−1. This study significantly contributes to the chemical and biological knowledge of a species that has not yet been scientifically explored.