White tea extract modified green synthesis of magnetite supported Ag nanoparticles: Evaluation of its catalytic activity, antioxidant and anti-colon cancer effects

Abstract

In this study, an eco-friendly and low-cost procedure for the synthesis of White tea plant extract modified magnetic nanocomposite (Fe 3 O 4 @ W.tea ) has been demonstrated. Ag nanoparticles (Ag NPs) were further decorated in situ over the designed Fe 3 O 4 @ W.tea nanocomposite exploiting the plant derived phytochemicals as bio-reductant and stabilizer. The resulting Fe 3 O 4 @ W.tea /Ag nanocomposite was characterized by various analytical methods like Fourier Transformed Infra Red (FT-IR) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), energy dispersive X-ray analysis (EDX) elemental mapping, transmission electron microscopy (TEM), vibrating-sample magnetometer (VSM), X-ray diffraction analysis (XRD), and inductively coupled plasma-atomic emission spectrometry (ICP-AES) analysis. 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 superparamagnetic 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 dependently. The IC 50 values observed in the two cell lines were 384.2 μg/ml and 254.6 μg/ml respectively. In addition, DPPH radical scavenging test was performed for studying anti-oxidant activity. The results validate the administration of Fe 3 O 4 @ W.tea /Agnanocomposite as a competent colon protective drug in the clinical trial studies over human.