Biochemical characterization and inhibition of thermolabile hemolysin from by phenolic compounds.

(), a typical microorganism inhabiting marine ecosystems, uses pathogenic virulence molecules such as hemolysins to cause bacterial infections of both human and marine animals. The thermolabile hemolysin TLH lyses human erythrocytes by a phospholipase B/A2 enzymatic activity in egg-yolk lecithin. However, few studies have been characterized the biochemical properties and the use of TLH as a molecular target for natural compounds as an alternative to control infection. Here, we evaluated the biochemical and inhibition parameters of the recombinant TLH using enzymatic and hemolytic assays and determined the molecular interactions by in silico docking analysis. The highest enzymatic activity was at pH 8 and 50 °C, and it was inactivated by 20 min at 60 °C with Tm = 50.9 °C. Additionally, the flavonoids quercetin, epigallocatechin gallate, and morin inhibited the TLH activity with IC50 values of 4.5 µM, 6.3 µM, and 9.9 µM, respectively; while phenolics acids were not effective inhibitors for this enzyme. Boltzmann and Arrhenius equation analysis indicate that TLH is a thermolabile enzyme. The inhibition of both enzymatic and hemolytic activities by flavonoids agrees with molecular docking, suggesting that flavonoids could interact with the active site's amino acids. Future research is necessary to evaluate the antibacterial activity of flavonoids against in vivo.