Synthesis and biological evaluation of new pyranopyridine derivatives catalyzed by guanidinium chloride-functionalized γ-Fe2O3/HAp magnetic nanoparticles

Abstract

We, herein, describe the synthesis of hydroxyapatite-modified γ-Fe₂O₃ magnetic nanoparticles grafted with guanidinium chloride and their characterization by X-ray diffraction (XRD), thermo gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), energy dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS), transmission and scanning electron microscopy (TEM & SEM), and vibrating sample magnetometer (VSM) techniques. This newly developed nanocatalytic system has been explored as an efficient and recyclable nanocatalyst to effect the one-pot three-component condensation reactions of various aromatic aldehydes, malononitrile and 3-cyano-6-hydroxy-4-methyl-pyridin-2(1H)-one under solvent-free condition with excellent yields. The new pyranopyridine derivatives synthesized from this reaction were subjected to biological valuation as antioxidants by using an α,α-diphenyl-β-picrylhydrazyl (DPPH) free-radical scavenging assay and also for their antifungal capacity against the fungus Fusarium oxysporum. According to the experimental results, these products exhibit excellent antioxidant activity with an IC₅₀ value of 0.140 ± 0.003 to 0.751 ± 0.008 mg mL⁻¹. In addition, these compounds exhibited reasonable antifungal activity against the Fusarium oxysporum fungus. In summary, the guanidinium chloride-functionalized magnetically hybrid nanocatalyst hydroxyapatite encapsulated γ-Fe₂O₃ was found to be a quite excellent and recyclable catalytic system for the green synthesis of pyrano[2,3-b]pyridine derivatives having antioxidant and antifungal activities.