Inhibition of interaction between Staphylococcus aureus α-hemolysin and erythrocytes membrane by hydrolysable tannins: structure-related activity study

The objective of the study was a comparative analysis of the antihemolytic activity against two Staphylococcus aureus strains (8325-4 and NCTC 5655) as well as α-hemolysin and of the membrane modifying action of four hydrolysable tannins with different molecular mass and flexibility: 3,6-bis-O-di-O-galloyl-1,2,4-tri-O-galloyl-β-d-glucose (T1), 1,2,3,4,5-penta-O-galloyl-β-d-glucose (T2), 3-O-galloyl-1,2-valoneoyl-β-d-glucose (T3) and 1,2-di-O-galloyl-4,6-valoneoyl-β-d-glucose (T4). We showed that all the compounds studied manifested antihemolytic effects in the range of 5–50 µM concentrations. However, the degree of the reduction of hemolysis by the investigated tannins was not uniform. A valoneoyl group—containing compounds (T3 and T4) were less active. Inhibition of the hemolysis induced by α-hemolysin was also noticed on preincubated with the tannins and subsequently washed erythrocytes. In this case the efficiency again depended on the tannin structure and could be represented by the following order: T1 > T2 > T4 > T3. We also found a relationship between the degree of antihemolytic activity of the tannins studied and their capacity to increase the ordering parameter of the erythrocyte membrane outer layer and to change zeta potential. Overall, our study showed a potential of the T1 and T2 tannins as anti-virulence agents. The results of this study using tannins with different combinations of molecular mass and flexibility shed additional light on the role of tannin structure in activity manifestation.