Interaction between procyanidin (PC) fractions and cultured staphylococcal enterotoxin A (SEA) producing strain or purified SEA. (A) Interaction between PC fractions and cultured SEA-producing strains. Staphylococcus aureus C-29 was cultured with six PC fractions in BHI broth for 24 h at 37 °C; (B) Interaction between purified SEA and five PC fractions (di-, tri-, tetra-, penta-, and greater than pentamer) of treated or untreated SEA were incubated for 24 h at 37 °C. Then test samples of treated or untreated SEA were separated by SDS-PAGE under reducing conditions and analyzed by immunoblotting with anti-SEA antibodies. * represents p < 0.05 compared to the control, ** represents p < 0.01 compared to the control. Values represent the mean ± SD for three independent experiments.