Abstract / Summary
Abstract The Leguminosae (Fabaceae) family contains a wide variety of secondary metabolites with biological activities; however, the chemical composition and biological potential of some species, such as Parkia decussata Ducke, remain unknown. The objective of this study was to investigate the phytochemical composition of P. decussata and evaluate its antimicrobial and antioxidant activities. The methanolic leaf extract was partitioned to yield hexane, dichloromethane, ethyl acetate, and hydromethanolic phases. The methanolic leaf extract and its respective phases were analyzed by liquid chromatography-mass spectrometry (LC-MS/MS) combined with molecular networking using the Global Natural Products Social Molecular Networking 2 (GNPS2) platform. Lupeol and a mixture of β-sitosterol and stigmasterol were isolated from the hexane fraction, while quercetin was isolated from the ethyl acetate fraction; all compounds were characterized by nuclear magnetic resonance (NMR) spectroscopy. LC-MS/MS and GNPS2 molecular networking enabled the annotation of C -glycosylated flavonoids, including isovitexin and vitexin, as well as (2 S ,3 S ,4 S ,5 R ,6 R )-6-(3-benzoyloxy-2-hydroxypropoxy)-3,4,5-trihydroxyoxane-2-carboxylic acid, gallic acid, ascorbic acid, esculetin, and coumarin. In the antimicrobial assays against Gram-positive and Gram-negative bacteria, the methanolic extract and ethyl acetate fraction showed the highest inhibitory activity. Regarding antioxidant activity, evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and Fe³⁺/phenanthroline assays, the ethyl acetate and hydromethanolic fractions showed the strongest activity, suggesting that phenolic compounds may contribute to the observed effects. To the best of our knowledge, this study provides the first report of quercetin, lupeol, β-sitosterol, and stigmasterol in P. decussata , as well as the first comprehensive description of the chemical constituents and biological activities of this species.