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This work describes the chemical and biological investigations of leaves and stems of Macrolobium latifolium (Vogel). The DCM, EtOAc soluble fractions obtained by liquid-liquid partition the crude methanolic extract of this species were submitted to usual chromatographic techniques which permitted to isolate an unusual 5,7-dihydroxychromone-3α- d -C-glucoside, named macrolobin, along with the known compounds identified as β-taraxerol, friedelin, stigmasterol, β-sitosterol, campesterol, and apigenin. The structures of all compounds were elucidated by 1H, 13C, HSQC and HMBC NMR spectra, IR spectra data analysis, and MS. Furthermore, the chemical profile from fatty acids and/or triglycerides fraction was also determined after transesterification. The reaction products were subjected to GC-FID and GC–MS permitted to detected methyl palmitate as the main fatty acid derivate present in the oil and, lauric (7.52 %), octadecanoic (17.15 %), docosanoic (5.36 %), tricosanoic (11.83 %) and tetracosanoic as minor methyl esters. Concerning the biological activities, the organic soluble fractions and macrolobin displayed antimicrobial activity against Salmonella enterica, Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli (MIC values 125−1000 μg.mL−1) and, macrolobin exhibited significant acetylcholinesterase inhibition (IC50 0.8 μM). These findings indicate M. latifolium can contribute with the development of new bioactive compounds, especially the AChE inhibition.

This work describes the isolation of pure bergenin from Peltophorum dubium roots with good yields and its further derivatization through Williamson synthesis. The alkyl derivatives of the bergenin were identified by nuclear magnetic resonance and mass spectrometry data analysis. Among them, three derivatives were reported for the first time herein, 8,10-dihexyl-bergenin, 8,10-didecyl-bergenin, and 8,10-ditetradecyl-bergenin, along with three previously reported ones (8,10-dimethylbergenin, 8-methylbergenin, 8,10-dioctyl-bergenin). Most derivatives of the bergenin displayed moderate cytotoxicity against Artemia salina, except the 8,10-dihexyl-bergenin (lethal concentration doses for 50% (LC50) = 70.55 µg mL-1). The antimicrobial assay showed that all derivatives selectively inhibited the Gram-positive bacteria Staphylococcus aureus, and two of them (8,10-dihexyl-bergenin and 8,10-didecyl-bergenin) had promising activities (minimum inhibitory concentration (MIC) = 5.1-6.2 µmol L-1). In addition, bergenin displayed interesting inhibition on acetylcholinesterase (half maximal inhibitory concentration (IC50) = 141.19 ± 0.41 µmol L-1), while its semi-synthetic derivatives displayed modest activity. Our results revealed that the antibacterial activity of bergenin could be greatly improved through its structural modification.