Biogenic Synthesis of Silver Nanoparticles from Avicennia marina Seed Extract and Its Antibacterial Potential

Abstract

Avicennia marina is the most abundant and widely distributed mangrove species and has been used in traditional medicine for treating skin diseases, rheumatism, ulcers, and smallpox. However, the biomedical potential of its seeds remains poorly characterized. The current contribution investigated the antibacterial potential of silver nanoparticles (AgNPs) synthesized from aqueous A. marina seed extract. When characterized using UV analysis and TEM analysis, the nanoparticles exhibited maximum absorption at 420 nm and average size of 5–10 nm. Analysis by FTIR revealed eight prominent absorption peaks at 3333, 3305, 2927, 2107, 1565, 1301, 1135, and 773 cm−1 suggesting the involvement of amide, carboxylic, aliphatic amines, and amino acid groups in the seed extract in the capping of nanoparticles. The AgNPs displayed inhibitory activity against a range of human pathogenic bacterial species: Escherichia coli (ATCC 35218), Klebsiella pneumoniae (ATCC 700603), Staphylococcus aureus (ATCC 43300), Enterococcus faecalis (ATCC 5129), and Pseudomonas aeruginosa (ATCC 27853). E. coli was the most sensitive to the silver nanoparticles (MIC 6.25 μg/mL) followed by K. pneumonia and P. aeruginosa (MIC 12.5 μg/mL). E. faecalis was resistant to silver nanoparticles. The biosynthesized AgNPs from A. marina seed extract display broad spectrum antibacterial activity and may be useful in treating antibiotic-resistant strains of bacteria.