Document Type : Original Article

Authors

• Sirous Ghobadi ¹
• Noushin Bijari ²
• Katayoun Derakhshandeh ³

¹ Associate Professor, Department of Biology, Faculty of Science, Razi University, Kermanshah, Iran

² Department of Biology, Faculty of Basic Sciences, Semnan University Semnan, Iran

³ Department of Pharmaceutics, School of Pharmacy, Hamadan University of Medical Sciences, Hamadan, Iran

Abstract

Irinotecan is considered to be one of the most effective anticancer drugs for colorectal cancer therapy. In this study, the role of human serum albumin (HSA), as a protein biopolymer and safe drug delivery system, in the binding of irinotecan was surveyed. The interaction between irinotecan and HSA has been studied by fluorimetry, circular dichroism (CD) and Fourier transform infrared (FT-IR) spectroscopy as well as molecular docking study. By the analysis of the fluorescence spectra, it was observed that irinotecan can quench the intrinsic fluorescence of HSA through a static quenching procedure. The binding parameters were determined according to the modified Stern-Volmer equation and the enthalpy change (ΔH^° and entropy change (ΔS^°) of binding were calculated to be -19.11 kJ mol⁻¹ and 13.80 J mol⁻¹ K⁻¹, respectively. The Analysis of the thermodynamic parameters indicated that the hydrogen bonding and hydrophobic interactions played the dominant role in the stabilization of the irinotecan-HSA complex. The competitive site markers experiments indicated that the drug binds to the site I of HSA, confirmed by molecular docking. The distance, r, between the donor (HSA) and the acceptor (irinotecan) was obtained according to Förster’s theory of non-radiation energy transfer. The quantitative analysis of the far-UV CD and FT-IR spectra represented that irinotecan has induced some alterations in the secondary and tertiary structures of the protein.

Keywords

• Alkaloid, Fluorescence quenching
• Fluorescence resonance energy transfer
• Human serum albumin
• Irinotecan

Main Subjects

• Other