On the binding reaction of loratadine with human serum acute phase protein alpha 1-acid glycoprotein

Abstract

Loratadine is an important anti-allergic drug. It is a second generation antihistamine drug used to treat allergic rhinitis, hay fever and urticaria. Human serum alpha 1-acid glycoprotein (AG) is an important acute phase protein and its serum concentration is found to increase in inflammation and acute response.The binding interaction between loratadine and AG is studied using spectroscopy and molecular docking techniques. The results obtained from fluorescence quenching experiments demonstrated that the fluorescence intensity of AG is quenched by loratadine. Loratadine was found to bind AG with the binding constant of ≈10⁴ at 298 K. The Gibb’s free energy change was found to be negative for the interaction of loratadine with AG indicating the binding process is spontaneous. Binding of loratadine with AG induced ordered structures in the protein. Hydrogen bonding and hydrophobic interactions were the main bonding forces between AG–loratadine as revealed by molecular docking results. This study suggests the importance of binding of anti-allergic drug to AG spatially in the diseases where the plasma concentration of AG increases many folds and interaction with this protein becomes significant. This study will help in design of drug dosage and adjustment accordingly to achieve optimal treatment outcome.

Communicated by Ramaswamy H. Sarma

Keywords:

• Human serum alpha-1 acid glycoprotein
• fluorescence quenching
• circular dichroism
• molecular docking
• loratadine

Acknowledgment

Facilities provided by university of Tabuk are gratefully acknowledged. Authors are grateful to deanship of scientific research (DSR) University of Tabuk for funding of this research group no. 0099-1441-S.

Additional information

Funding

Authors would like to extend their sincere appreciation to the deanship of scientific research at University of Tabuk for its funding of this research group no. 0099-1441-S.