BackgroundNatural products are an important source of bioproducts with pharmacological properties. Here we investigate the components of leaves fromM. tomentosaBenth. (Fritsch) (Chrysobalanaceae) and its effects on bacterial cell growth, biofilm production and macrophage activity.MethodsThe effect of the different leaf extracts against bacterial cell growth was performed using the microdilution method. The most active extract was analyzed by mass spectrometry, and its effect on bacterial biofilm production was evaluated on polystyrene plates. The extract effect on macrophage activity was tested in the RAW264.7 cell line, which was stimulated with different concentrations of the extract in the presence or absence of LPS.ResultsWe show that the ethyl acetate (EtOAc) extract was the most effective against bacterial cell growth. EtOAc extract DI-ESI (-)MSnanalysis showed the presence of a glycosylated flavonoid tentatively assigned as myricetin 3-O-xylosyl-rhamnoside (MW 596). Also, the EtOAc extract increased biofilm formation byS. aureusand inhibited cytokine and NO production induced by LPS in RAW macrophages.ConclusionM. tomentosaflavonoid-enriched EtOAc extract presented a bactericidal and anti-inflammatory pharmacological potential.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12906-023-03968-z.