Effects of hesperidin, a flavanone glycoside interaction on the conformation, stability, and aggregation of lysozyme: multispectroscopic and molecular dynamic simulation studies?

Abstract

Hesperidin (HESP), a flavanone glycoside, shows high antioxidant properties and posses ability to go through the blood–brain barrier. Therefore, it could be a potential drug molecule against aggregation based diseases such as Alzheimer’s, Parkinson’s, and systemic amyloidoses. In this work, we investigated the potential of HESP to interact with hen egg-white lysozyme (HEWL) monomer and prevent its aggregation. The HESP–HEWL binding studies were performed using a fluorescence quenching technique, molecular docking and molecular dynamics simulations. We found a strong interaction of HESP with the lysozyme monomer (K_a, ~ 5 × 10⁴ M⁻¹) mainly through hydrogen bonding, water bridges, and hydrophobic interactions. We showed that HESP molecule spanned the highly aggregation prone region (amino acid residues 48-101) of HEWL and prevented its fibrillar aggregation. Further, we found that HESP binding completely inhibited amorphous aggregation of the protein induced by disulfide-reducing agent tries-(2-carboxyethyl) phosphine. Conformational and stability studies as followed by various tertiary and secondary structure probes revealed that HESP binding only marginally affected the lysozyme monomer conformation and increased both stability and reversibility of the protein against thermal denaturation. Future studies should investigate detail effects of HESP on solvent dynamics, structure, and toxicity of various aggregates. The answers to these questions will not only target the basic sciences, but also have application in biomedical and biotechnological sciences.

Keywords:

• optical spectroscopy
• aggregation inhibition
• protein misfolding
• ligand–protein binding
• fluorescence quenching
• molecular dynamics simulations

Acknowledgment

The authors gratefully acknowledge the UM-DAE Centre for Excellence in Basic Sciences, UGC-Faculty Recharge Programme (UGC-FRP), and University of Mumbai for laboratory facilities and financial assistance. RRSP acknowledges DST-SERB (SR/SO/HS-0117/2012) for the computational facility provided at the Bombay College of Pharmacy.