Introduction. The research of new alternatives to antimicrobial resistance has led to the exploration of medicinal plant extracts. Luma chequen has antimicrobial activity, but the secondary metabolites have not been identified. Objective. Characterize the chemical structures of flavonoids and to evaluate the antimicrobial activity of the methanolic extract of Luma chequen (Molina) A. Gray leaves. Methods. The methanolic extract of the leaves was prepared and its solubility with solvents of increasing polarity was evaluated, then a phytochemical screening was carried out, identifying different secondary metabolites. Thin layer chromatography (TLC) used standards and developers. The chemical structures of the flavonoids present in the methanolic extract were characterized by UV-Visible spectroscopy and displacement reagents. The antimicrobial activity was determined by the agar-well diffus...