Spectrophotometric Investigations of Charge Transfer Complexes of Tyrosine Kinase Inhibitors with Iodine as a σ-Electron Acceptor: Application to Development of Universal High-Throughput Microwell Assay for Their Determination in Pharmaceutical Formulations

Spectrophotometric and computational characterization of charge transfer complex of selumetinib with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone and its utilization in developing an innovative green and high throughput microwell assay for analysis of bulk form and pharmaceutical formulation

For paediatric patients suffering from neurofibromatosis, Selumetinib (SEL) is the only approved drug. Here an original ecofriendly and high pace method is introduced using 96- microwell spectrophotometric assay (MW-SPA) to measure SEL content in bulk and commercial pharmaceutical formulation (Koselugo® capsules). This assay was relied on in-microwell formation of a coloured charge transfer complex (CTC) upon interaction of SEL with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). The complex was fully characterized by spectrophotometric and computational studies. The CTC exhibited an absorbance maximum (λmax) at 440 nm. The ease of reaction occurrence, complex stability and its high absorptivity were proved by measuring its association constant (0.63 × 102 L/ mol), standard free energy change (-10.31 KJ/mol), molar absorptivity (ε) (3.78 × 103 L/mol/cm), and the SEL: DDQ stoichiometric ratio (1:1). Establishments of the optimum values of the applied conditions in 96-well assay plate were refined regarding DDQ concentration, reaction time, temperature, and solvents. Validation of the assay was according to the ICH guidelines. The assay was linear in SEL' concentrations ranged from 10 to 200 µg/well, with limits of detection and quantitation of 4.1 and 12.5 µg/well, respectively. Then, the assay was efficaciously adapted to accurately and precisely determine SEL content in bulk form and Koselugo® capsules. The assay environmental safety was documented by three different comprehensive metric tools. Additionally, assessment of the assay's rate demonstrated its high throughput, enabling the processing of large number of samples in pharmaceutical quality control laboratories. The successful development of this assay provides a valuable fast and green analytical tool for ensuring the quality control of SEL's bulk form and capsules.

Chitosan‑iodine complexes: Preparation, characterization, and antibacterial activity

Bacterial infections have always been a major threat to public health, and the development of effective antibacterial substances from natural polymers is crucial. 2-Aminoisonicotinic acid (AN) was grafted onto chitosan by 1-ethyl-(3-dimethylaminopropyl)carbodiimide-mediated coupling reactions, and then modified chitosan‑iodine (CSAN-I) complexes were prepared by solvent-assisted grinding. The samples were characterized using ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, proton nuclear magnetic resonance spectroscopy, and X-ray diffraction, confirming that CSAN-I complexes had been successfully prepared. Thermogravimetric (TG) analysis indicated that the chemical modification of chitosan and iodine complexation reduced the thermal stability; X-ray photoelectron spectroscopy (XPS) analysis revealed that 81 % of the iodine in CSAN-I complex was in the form of triiodide ions. The iodine contents of three CSAN-I complexes (CSAN-I-1, CSAN-I-2 and CSAN-I-3) were 1.59 ± 0.22 %, 3.18 ± 0.26 %, and 5.56 ± 0.41 %, respectively. The antibacterial effects were evaluated in vitro, and the results indicated that CSAN-I complexes had strong antibacterial activities against both E. coli and S. aureus. In particular, CSAN-I-3 exhibited the best antibacterial effect. In addition, CSAN-I-3 was nontoxic to L929 cells with good cytocompatibility. Therefore, CSAN-I complexes can be considered as promising candidates for wound management in clinical applications.

Spectrophotometric Study of Charge-Transfer Complexes of Ruxolitinib with Chloranilic Acid and 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone: An Application to the Development of a Green and High-Throughput Microwell Method for Quantification of Ruxolitinib in Its Pharmaceutical Formulations

Ruxolitinib (RUX) is a potent drug that has been approved by the Food and Drug Administration for the treatment of myelofibrosis, polycythemia vera, and graft-versus-host disease. This study describes the formation of colored charge-transfer complexes (CTCs) of RUX, an electron donor, with chloranilic acid (CLA) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), the π-electron acceptors. The CTCs were characterized using UV-visible spectrophotometry. The formation of CTCs in methanol was confirmed via formation of new absorption bands with maximum absorption at 530 and 470 nm for CTCs with CLA and DDQ, respectively. The molar absorptivity and other physicochemical and electronic properties of CTCs were determined. The molar ratio was found to be 1:1 for both CTCs with CLA and CTCs with DDQ. The site of interaction on RUX molecules was assigned and the mechanisms of the reactions were postulated. The reactions were employed as basis for the development of a novel green and one-step microwell spectrophotometric method (MW-SPM) for high-throughput quantitation of RUX. Reactions of RUX with CLA and DDQ were carried out in 96-well transparent plates, and the absorbances of the colored CTCs were measured by an absorbance microplate reader. The MW-SPM was validated according to the ICH guidelines. The limits of quantitation were 7.5 and 12.6 µg/mL for the methods involving reactions with CLA and DDQ, respectively. The method was applied with great reliability to the quantitation of RUX content in Jakavi® tablets and Opzelura® cream. The greenness of the MW-SPM was assessed by three different metric tools, and the results proved that the method fulfills the requirements of green analytical approaches. In addition, the one-step reactions and simultaneous handling of a large number of samples with micro-volumes using the proposed method enables the high-throughput analysis. In conclusion, this study describes the first MW-SPM, a valuable analytical tool for the quality control of pharmaceutical formulations of RUX.