Green Synthesis, Characterization and Biological Activities of Gold Nanoparticles (AuNP) Synthesized Using Extract of Melilotus indicus L.

In this study for the first-time gold nanoparticles (AuNPs) were synthesized (MiAuNPs) using Melilotus indicus L. extract (MiExt) by eco-friendly method for different bioactivity applications. Various analytical techniques used for identifying properties of MiAuNPs include powder X-ray diffraction, UV-Vis absorption spectroscopy, Fourier-Transform Infrared Radiation (FT-IR), and scanning electron microscopy (SEM). The average diameter of MiAuNPs was about 8 nm (crystallite size by XRD was estimated around 13 nm). Antimicrobial activities MiAuNPs revealed significant effect against Gram-positive (Staphylococcus aureus), Gram-negative (Escherichia coli, Proteus mirabilis, and Shigella flexneri) and fungi (Candida albicans). The anticancer activity which may be found in the MiExt as well as extract with MiAuNPs was checked using HepG2 and HeLa cell lines. Results revealed that the MiExt alone was stimulatory to Hela cells growth, while MiAuNPs inhibit it. Both MiExt and MiAuNPs also inhibited HepG2 growth. For larvicidal properties, MiExt and MiAuNPs were tested for larvicidal toxicity effects against 4th instar larvae of the common house mosquito viz., Culex pipiens. MiAuNPs was found more lethal against Cx. pipiens with lower lethal concentration values (LC50 = 333.961 ppm; LC90 = 1433.208 ppm), compared to only MiExt (LC50 = 1815.12 ppm; LC90 = 7164.094 ppm).

Automated summary

Gold nanoparticles (MiAuNPs) synthesized using an eco-friendly method with Melilotus indicus L. extract showed significant antimicrobial, anticancer, and larvicidal activities, inhibiting the growth of various microorganisms and cell lines while displaying toxic effects on larvae of the common house mosquito.