Stability Indicating Method for a Thiazolylhydrazone Derivative with Antifungal Activity and Experimental/Theoretical Elucidation of Its Degradation Products

RN104 (2-[2-(cyclohexylmethylene)hydrazinyl]-4-phenylthiazole) is a thiazolylhydrazone derivative with promising in vitro and in vivo antifungal activity. A stability indicating high performance liquid chromatography with diode-array detection (HPLC-DAD) method was carried out using C18 end-capped column (250 × 4.6 mm, 5 μm) and a mobile phase composed of water and acetonitrile (15:85 v/v) at a flow rate of 1.2 mL min-1, injection volume 25 μL and DAD detection at 240 nm. The method showed to be selective, linear in the range of 20 to 240 μg mL-1, precise, accurate and robust. RN104 forced degradation study under different stress conditions (acidic, alkaline and neutral hydrolysis, oxidation, photolysis and thermolysis) was performed using the validated analytical method. The results showed that RN104 underwent significant degradation when subjected to alkaline hydrolysis and oxidation by metallic ions. Quantum mechanics calculations were carried out to assist in the structural elucidation of the formed degradation products. The obtained data may be useful for the development of future formulation based on RN104.