An extract from Vauquelinia corymbosa Bonpl. (Rosaceae) showed noted inhibitory effect (IC50= 28.6 µg/mL) against yeast α-glucosidase when tested with a well-known spectrophotocolorimetric assay. Bioassay-guided fractionation the active extract led to the isolation of prunasin (1), (-)-epi-catechin (2), hyperoside (3), isoquercetin (4), quercitrin (5), quercetin-3-O-(6''-benzoyl)-β-galactoside (6), picein (7) and methylarbutin (8). The most active compound was 6 with an IC50 of 30µM; according to a kinetic analysis compound 6 behaved as mixed-type inhibitor (ki= 50µM; α= 0.97). The information generated in this study indicates that V. corymbosa is a source of new α-glucosidase inhibitors which might delay glucose absorption in vivo. The presence of compounds 1 – 6 in the plant might explain the reputed antidiabetic activity of V. corymbosa in Mexican folk medicine. Concerning the occurrence of prunasin (1) in this species, National Health Authorities should provide effective communication to consumers about the risk from its inappropriate usage.