Stress Degradation Study of Bosutinib and Structural Elucidation of Its Degradation Impurities by Using LC-Q-TOF-MS/MS and NMR

Bosutinib monohydrate (BST) is an anticancer medicine used to treat Philadelphia chromosome-positive (Ph+) chronic myeloid leukemia. The present research focuses on the separation and structural elucidation of degradation impurities of BST using reversed-phase chromatography, mass spectrometry, and nuclear magnetic resonance spectroscopy methods. As per the International Council for Harmonisation (ICH) Q1A and Q1B guidelines, the stress degradation experiments on BST were carried out. The separation of degradation impurities was accomplished on an RP-HPLC using Agilent ZORBAX Eclipse plus C18 column (4.6 × 250 mm, 5 μm) on a gradient program with a flow rate of 1 mL/min, and 0.1% formic acid in water (%A) and acetonitrile (%B) as the mobile phases. Eight degradation impurities were detected in basic hydrolysis, oxidative conditions (H₂O₂), and photolytic (UV light and visible light) conditions. Structural elucidation of degradation impurities was performed by LC-Q-TOF-MS/MS. The obtained experimental masses were used to propose the fragmentation patterns and structures of BST and its degradation impurities. The data obtained from the mass spectrometry were used to propose the mechanism for the formation of the degradation impurities. The DI B-6 was isolated and NMR studies were performed for the confirmation of its structure. Zeneth was used to anticipate the in silico degradation profile of BST. The structures of seven degradation impurities matched with the in silico predictions of Zeneth. DEREK Nexus and SARAH Nexus were the in silico tools used to predict toxicity and mutagenicity. Thus, the outcomes attained from this study could be relevant for regular analysis and stability testing of BST in quality control laboratories.