Charge-Transfer Complex of Linifanib with 2,3-dichloro-3,5-dicyano-1,4-benzoquinone: Synthesis, Spectroscopic Characterization, Computational Molecular Modelling and Application in the Development of Novel 96-microwell Spectrophotometric Assay

Abstract

Background

Linifanib (LFB) is a multi‐targeted receptor tyrosine kinase inhibitor used in the treatment of hepatocellular carcinoma and other types of cancer. The charge-transfer (CT) interaction of LFB is important in studying its receptor binding mechanisms and useful in the development of a reliable CT-based spectrophotometric assay for LFB in its pharmaceutical formulation to assure its therapeutic benefits.

Purpose

The aim of this study was to investigate the CT reaction of LFB with 2,3-dichloro-3,5-dicyano-1,4-benzoquinone (DDQ) and its application in the development of a novel 96-microwell spectrophotometric assay for LFB.

Methods

The reaction was investigated, its conditions were optimized, the physicochemical and constants of the CT complex and stoichiometric ratio of the complex were determined. The solid-state LFB-DDQ complex was synthesized and its structure was analyzed by UV-visible, FT-IR, and ¹H-NMR spectroscopic techniques, and also by the computational molecular modeling. The reaction was employed in the development of a novel 96-microwell spectrophotometric assay for LFB.

Results

The reaction resulted in the formation of a red-colored product, and the spectrophotometric investigations confirmed that the reaction had a CT nature. The molar absorptivity of the complex was linearly correlated with the dielectric constant and polarity index of the solvent; the correlation coefficients were 0.9526 and 0.9459, respectively. The stoichiometric ratio of LFB:DDQ was 1:2. The spectroscopic and computational data confirmed the sites of interaction on the LFB molecule, and accordingly, the reaction mechanism was postulated. The reaction was utilized in the development of the first 96-microwell spectrophotometric assay for LFB. The assay limits of detection and quantitation were 1.31 and 3.96 μg/well, respectively. The assay was successfully applied to the analysis of LFB in its bulk and tablets with high accuracy and precision.

Conclusion

The assay is simple, rapid, accurate, eco-friendly as it consumes low volumes of organic solvent, and has high analysis throughput.

Keywords:

• linifanib
• 2,3-dichloro-3,5-dicyano-1,4-benzoquinone
• charge-transfer reaction
• spectroscopic techniques
• 96-microwell spectrophotometric assay
• high-throughput pharmaceutical analysis

Acknowledgments

The authors would like to extend their appreciation to the Deanship of Scientific Research at King Saud University for its funding of this research through the research group project No. RGP-225.

Abbreviations

CT, charge transfer; LFB, linifanib; QC, quality control; DDQ, 2,3-dichloro-3,5-dicyano-1,4-benzoquinone; RTKIs, receptor tyrosine kinase inhibitors; VEGFR, vascular endothelial growth factor receptor; PDGFR, platelet-derived growth factor receptor; LOD, limit of detection; LOQ, limit of quantitation; RSD, relative standard deviation.

Disclosure

The authors report no conflicts of interest in this work.