GREEN SYNTHESIS OF SILVER NANOPARTICLES FROM FIVE SPECIES OF CYPERUS GENUS AND CHARACTERIZATION OF THEIR BIO FUNCTIONAL AND CATALYTIC PROPERTIES

Abstract

Nanotechnology offers a sustainable approach for synthesising materials at the nanoscale, enhancing their physicochemical and biological properties. This study investigated the green synthesis of silver nanoparticles (AgNPs) using aqueous root extracts (AEs) of five Cyperus species, namely C. mindorensis, C. esculentus, C. alternifolius, C. rotundus, and C. eragrostis. Phytochemical screening revealed the presence of carbohydrates, saponins, proteins, and quinones in all AEs, while tannins and carboxylic acids were absent. SEM analysis confirmed spherical AgNPs of 20–50 nm. Compared to AEs, AgNPs showed significantly higher total flavonoid content (TFC), total phenolic content (TPC), and total antioxidant capacity (TAC). C. esculentus AEs showed 746.09 g/QE/100g for TFC, 543.34 g/GAE/100g for TPC, 52.988 g/AAE/100g for TAC, and AgNPs exhibited the highest TFC level (4.2 g/QE/100g), the highest TAC levels (319 g/AAE/100g), and the highest TPC levels (2158 g/GAE/100g). The antibacterial potential m of the synthesised AgNPs was evaluated using the well diffusion method with gentamycin serving as positive control, revealing significant inhibitory activity against E. coli and S. aureus. Notable zones of inhibition were observed: C. esculentus – 11 mm, C. alternifolius – 11 mm, C. rotundus – 10 mm, and C. eragrostis – 11 mm. But C. mindorensis-AgNPs did not exhibit antibacterial properties. Cytotoxicity tests using Artemia salina indicated 100% viability across all AgNP concentrations, confirming biocompatibility. In catalysis studies, AgNPs facilitated the reduction of para-nitrophenol (PNP) to para-aminophenol (PAP), with C. esculentus-AgNPs showing the highest rate constant (0.1351 min⁻¹). Degradation of PNP was observed within 20 min at 420 nm, and formation of PAP was observed at 320 nm. Photocatalytic degradation experiments were performed with both methylene blue (MB) and methyl orange (MO). Photocatalytic degradation of MB and MO was faster with 4000ppm AgNPs, while 267ppm AgNPs showed enhanced degradation when combined with NaBH4. 4000ppm showed higher degradation with AgNPs and AgNPs with NaBH4. Bioinformatic docking analysis revealed silver ion binding with key residues (Ser127, Asn124) of the TRAF1 (1KZN) protein (pbd_00001kzn), suggesting potential anticancer applications. These results demonstrate that Cyperus-derived AgNPs possess multifunctional properties, highlighting their potential use in biomedical and environmental fields.