Spectroscopic and molecular modeling investigation on the interactions between hyaluronidase and baicalein and chrysin

• The inhibitory effects of baicalein and chrysin on hyaluronidase were measured.
• Binding mechanisms were first investigated by spectral and docking methods.
• HAase fluorescence was quenched via static quenching with r less than 7 nm.
• Multi-fluorescence spectra of flavone–HAase systems were showed in paper.
• The interaction of HAase with flavones occurred in the hydrophobic cavity.

In the work described on this paper, the bindings of baicalein and chrysin with hyaluronidase (HAase) were studied by fluorescence, synchronous fluorescence, three-dimensional fluorescence and molecular docking methods. The results indicated that both of flavones could interact with HAase to form flavone–HAase complexes. The binding constant, number of binding sites and thermodynamic parameters were measured at different temperature, which indicated that flavones could spontaneously bind with HAase through electrostatic forces with one binding site. Based on synchronous and three-dimensional fluorescence spectra and the molecular docking results, both of flavones bound directly into the enzyme cavity site and the binding of flavones into the enzyme cavity influenced the microenvironment of the HAase activity site which resulted in the reduced HAase activity. The present study provides direct evidence at a molecular level to understand the mechanism of inhibitory effect of flavone against HAase and explain the anti-inflammatory mechanism of Scutellaria baicalensis Georgi as an anti-inflammatory drug.