Pharmacokinetic and biotransformation analysis of thiophene- and dichlorophenyl-substituted indole-3-butyric acid hydrazones

Background: The indole-3-butyric acid based hydrazones have gained attention due to their reported biological effectiveness; however, their in-vivo pharmacokinetic properties and metabolic pathways are yet inadequately investigated. Comprehending structure-dependent variations in absorption and metabolism is essential for the preliminary optimization of this scaffold. Objectives: The aim of the study was to comparatively assess the pharmacokinetics and biotransformation of two IBA-based hydrazones—4-indole-3-butane-(thiophen-2-ylmethylene) hydrazone (TIBH) and 1-(4-amino-3,5-dichlorophenyl) ethylidene-4-indole-3-butane hydrazone (DIBH) and to clarify the impact of structural substitution on their metabolic pathways in-vivo. Methods: UV–VIS spectrophotometry under verified linear circumstances assessed serum concentrations over 24 hr in healthy rats after a single oral dosage (10 mg/kg). Metabolites and temporal profiles were identified using LC–ESI–MS/MS. Biotransformer 3.0 was used for cheminformatic prediction of metabolic pathways and enzyme participation. In exploratory analysis, data are presented descriptively (mean ± SD). Results: TIBH demonstrated accelerated absorption with an earlier peak concentration (Cmax at 4 hr) and a reduced half-life, while DIBH exhibited a delayed peak exposure (Cmax at 8 hr) and extended systemic persistence. The LC–MS/MS study showed that both compounds went through a lot of Phase-I (hydrolysis, hydroxylation and deamination) and Phase-II (glucuronidation, sulfonation and acetylation) metabolism. This made them more polar and facilitating elimination. Different metabolite profiles showed how substitution changed metabolism. TIBH had faster oxidative and conjugative turnover, while DIBH was more stable with late stage dechlorination. The predicted routes and enzyme involvement aligned well with the experimental results. Conclusion: This research indicated that aromatic substitution significantly affects the pharmacokinetic and metabolic properties of IBA-based hydrazones. Despite its constraints due to an exploratory design and absence of pharmacological validation, the combined experimental and computational methodology offers mechanistic understanding of structure–metabolism connections and guides subsequent optimization and biological assessment of hydrazone scaffolds.