Silver Nanoparticles Of Clinacanthus Nutans Aqueous Extract: Biosynthesis, Phytochemical And Selected Biological Activities
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Date
2018-07
Authors
Che Nurul Azieyan Che Mood
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Publisher
Universiti Sains Malaysia
Abstract
The use of plant to synthesise silver nanoparticles (AgNPs) is considered as a green technology. In this study, a non-toxic, cost effective and eco-friendly method has been applied to synthesise AgNPs using aqueous extract of leaf and stem of Clinacanthus nutans (C. nutans). The synthesised AgNPs were tested on antimicrobial, antioxidant and cytotoxicity activities. The formation of AgNPs was confirmed by UV-Vis spectroscopy at the wavelength of 420 nm (AgNP-L) and 430 nm (AgNP-S). The size were measured at 114 nm (AgNP-L) and 129 nm (AgNP-S) using a zetasizer. From TEM analysis, the size ranged from 10-300 nm and 10-180 nm for AgNP-L and AgNP-S with spherical shape. Zeta potentials recorded at -42.8 mV for AgNP-L and -43.9 mV for AgNP-S. XRD analysis matched the face-centered cubic (fcc) structure of silver. FTIR analysis revealed the presence of few functional groups of phenolic and flavonoid compounds which acts as the reducing agent in AgNPs synthesis. The AgNPs showed good inhibition against bacteria, but not fungus. Inhibition showed that highest against S. aureus with 11.35 mm (AgNP-L) and 11.52 mm (AgNP-S), while the lowest inhibition against E. coli with 9.22 mm (AgNP-L) and 9.25 mm (AgNP-S) in disc diffusion method. Same trend of result was reported for well diffusion method. In antioxidant assays, AgNP-L showed IC50 at 417.05 μg/mL and AgNP-S at 434.60 μg/mL (DPPH); 304.31 μg/mL (AgNP-L) and 326.83 μg/mL (AgNP-S) for ABTS, respectively. FRAP assay showed AgNP-L [872.389 μmol/L Fe(II)] and AgNP-S [612.770 μmol/L Fe(II)], respectively were significantly (p<0.05) higher in antioxidant activity compared to plant extracts (CNL; 152.260 μmol/L Fe(II) and CNS; 110.445 μmol/L Fe(II)). The AgNPs were also proven to possess cytotoxicity effect on cancer cell lines of MCF-7, HT-29 and HeLa in dose-dependent manner. AgNP-S and AgNP-L showed significantly (p<0.05) higher cytotoxicity against MCF-7 (117.43 μg/mL) and HT-29 (78.47 μg/mL), respectively. In conclusion, the biosynthesised AgNPs from aqueous extract leaves and stem of C. nutans provide promising bioactivities towards antioxidant, anti-microbial and cytotoxicity activities.
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