Pyridoxal and Salicylaldehyde Derivatives: Synthesis, Characterization, and Antifungal Potential Against Opportunistic Yeast Pathogens

This study reports the synthesis, characterization, and antifungal evaluation of a series of pyridoxal and salicylaldehyde derivatives, using synthetic methodologies such as radical cyclizations and click chemistry. Compounds 6a and 6b, featuring a fused dihydrobenzoxepine-pyridine scaffold, demonstrated effective fungicidal activity with MIC values of 19 µg/mL against Cryptococcus neoformans 2807. Similarly, compound 6b exhibited notable activity with a MIC of 75 µg/mL against Candida auris PUJ-HUSI 537. Both compounds outperformed fluconazole (FLC) in these strains. In silico ADMET profiling revealed favorable pharmacokinetic properties, including blood–brain barrier penetration and drug-likeness parameters consistent with Lipinski’s rule of five. Cytotoxicity assays on human fibroblasts confirmed the low toxicity of compound 6a at the tested concentrations. These results highlight the potential of the fused dihydrobenzoxepine-pyridine scaffold as a promising antifungal candidate for further investigations.