Abstract
Plant-derived natural products represent a significant source of green chemical compounds. The fruit extract of Emblica officinalis Gaertn., a traditionally used medicinal plant, was exploited in green synthesis of silver nanoparticles (AgNPs) using AgNO3 reduction method. Characterization of the synthesized AgNPs was achieved using UV-Vis, FTIR spectroscopy as well as transmission electron microscopy (TEM). The antioxidant and cytotoxic activities of the extract and AgNPs were investigated. The synthesized AgNPs exhibited moderate inhibition of ABTS(center dot+) (67.2%) compared to the fruit extract (89.9%) and L-ascorbic acid (90.7%). Likewise, the extract exhibited higher cytotoxicity against MCF-7 and HCT-116 (IC50 25 and 20 mu g/mL, respectively) compared to AgNPs (IC50 75 and 80 mu g/mL, respectively). These results indicated that the functional groups of the biomolecules were quenched during the Ag+ reduction and surface capping processes. Phytochemical investigation of the active extract led to the isolation of a new hexagalloyl derivative designated as emblifatmin (E4), in addition to four known compounds, namely trans-cinnamic acid (E1), methyl gallate (E2), gallic acid (E3), and quercetin-3-O-alpha-arabinofuranoside (E5), identified by MS and NMR spectroscopy. The new compound, emblifatmin showed a remarkable AgNPs synthetic capability (minimum active concentration, MAC 0.0019 mg/mL) and considerable ABTS(center dot+) antioxidant activity (83.9%).