Bio-supported of Cu nanoparticles on the surface of Fe3O4 magnetic nanoparticles mediated by Hibiscus sabdariffa extract: Evaluation of its catalytic activity for synthesis of pyrano[3,2-c]chromenes and study of its anti-colon cancer properties

In this work, we have described the biogenic synthesized copper nanoparticles being supported over plant phytochemicals modified magnetic Fe3O4 nanoparticles. Hibiscus sabdariffa extract was used as a green reducing agent and an excellent stabilizer of the synthesized NPs. The biomolecules are adorned as a protective shell over the core ferrite NPs. Physicochemical characterization of the as-synthesized Cu-Hibiscus@Fe3O4 nanocomposite was carried out through Fourier transformed infrared spectroscopy (FT-IR), electron microscopy (SEM and TEM), energy dispersive X-ray spectroscopy (EDX), elemental mapping (WDX), vibrating sample magnetometer (VSM), X-ray diffraction (XRD) and inductively coupled plasma-optical emission spectroscopy (ICP-OES). The as-synthesized bio-nanomaterial was used as an excellent heterogeneous and magnetically retrievable catalyst in the three-component condensation of 4-hydroxycoumarin, malononitrile and various aldehydes in refluxing aqueous media. A broad range of aromatic aldehydes underwent the reaction to produce diverse pyrano[3,2-c]chromene derivatives in very good yields irrespective of the nature of bearing functional groups or their respective geometrical positions. Due to superparamagentic character, the material was easily magnetically decanted out and recycled for 8 successive times with preservation of its catalytic activity. After the chemical applications we also explored the material biologically in the resistance of human colon cancer and thereby studied the cytotoxicity over two standard cell lines, HT-29 and Caco-2. The conventional MTT assay was carried out over them which revealed an increase in % cell viability dose dependantly. In addition, DPPH radical scavenging test was performed for studying anti-oxidant activity, using BHT as the positive control. The IC50 values observed in the two cell lines were 490.12 μg/ml and 412.23 μg/ml respectively. The results validate the administration of Cu-Hibiscus@Fe3O4 as a competent colon protective drug in the clinical trial studies over human.