Green synthesis of silver nanoparticles using Omani pomegranate peel extract and two polyphenolic natural products: characterization and comparison of their antioxidant, antibacterial, and cytotoxic activities

Abstract

Abstract Background Green synthesis of silver nanoparticles (AgNPs) has gained popularity due to the economical and eco-friendly approach associated with it. The aim of the study was to biosynthesize silver nanoparticles using pomegranate peel extract (PPE), quercetin (Q), and gallic acid (GA) and to evaluate their antioxidant, antimicrobial, and cytotoxic activities. Results A sharp color change from yellow to brown, appearance of a peak in a UV spectrum around 413–425 nm, and four intense peaks in XRD spectra matching with the reference silver crystal confirmed the formation of AgNPs. SEM and TEM analysis revealed particles to be mostly spherical with few aggregates. Average particle size distribution and zeta potential was found to be 43.6 nm and −18.01mV, 31.6 nm and −21.5 mV, and 21.7 nm and −27.9 mV for Q-AgNPs, P-AgNPs, and GA-AgNPs, respectively. P-AgNPs showed excellent in vitro antioxidant activity (84.85–89.20%) and cytotoxic activity (100% mortality). P-AgNPs and GA-AgNPs exhibited good antimicrobial activity against the four bacterial strains comparable to the reference antibiotics but Q-AgNPs failed to inhibit the growth of P. vulgaris. Conclusions Omani pomegranate peel extract seems to be a potential and alternative source for the simple, one pot, eco-friendly green synthesis of extracellular stable AgNPs. The synthesized nanoparticles have the potential to be developed as possible antimicrobial agents and antioxidants. Graphical abstract

Keywords

• Green synthesis
• Silver nanoparticles
• Antioxidant
• Cytotoxic
• AgNO3