Green Synthesis of Gold Nanoflowers Using Rosmarinus officinalis and Helichrysum italicum Extracts: Comparative Studies of Their Antimicrobial and Antibiofilm Activities

Abstract

This study was concerned with the green synthesis of gold nanoflowers (AuNFs) using the bioactive constituents of Rosmarinus officinalis (rosemary) and Helichrysum italicum (immortelle) extracts, as reducer and stabilizer agents along with the determination of their antibacterial and antibiofilm activity against E. coli, S. aureus, and S. epidermidis. The AuNFs were characterized using STEM, UV–Vis, DLS, ZETA, FESEM-EDX, and FTIR techniques. The antibacterial and antibiofilm activity of the AuNFs were evaluated by microdilution broth and microtiter plate (MTP) tests, respectively. STEM and DLS analysis confirmed the flower-like morphology of gold nanoparticle clusters of R. officinalis-AuNFs (R-AuNFs) and H. italicum-AuNFs (H-AuNFs) with a size of 20–130 nm and 15–90 nm, respectively. The MICs of R-AuNFs were found to be 40 µg/mL for E. coli and S. epidermidis and 160 µg/mL for S. aureus. The MICs of H-AuNFs against all bacterial strains were 20 µg/mL. All tested AuNFs exhibited a strong dose-dependent antibiofilm activity against the test strains, and H-AuNFs was more effective than R-AuNFs. The green synthesis of AuNFs from the rosemary and immortelle extracts can be applied as a potential agent to overcome the growth of biofilm-producing microorganisms in food industries.

Green Synthesis, Characterization and Antibacterial Activity of Gold and Copper Nanoparticles from Lannea discolor (Sond.) Engl

“…Similar sizes were also previously reported by Borah et al using Syzygium cumini [39]. Onmaz et al reported sizes <100 nm NFs using Helichrysum italicum [40]. Other studies suggest that tannin-based polymers enhance reduction [41], explaining the unexpected formation of NFs from L discolor.…”

Green Synthesis of Gold and Copper Nanoparticles by Lannea discolor: Characterization and Antibacterial Activity

“…Borah et al reported similar sizes using Syzygium cumini [39]. Onmaz et al reported NFs of sizes < 100 nm using Helichrysum italicum [40]. Other studies suggest that tannin-based polymers enhance reduction [41], explaining the unexpected formation of NFs from L. discolor.…”

Natural Products/Bioactive Compounds as a Source of Anticancer Drugs

“…Over the last decade, several researchers have investigated the ethnopharmacological and ethnomedicinal properties of numerous plant-derived bioactive compounds and, recently, their antimicrobial and antibiofilm activities [ 35 ]. Several in vitro and in vivo experimental investigations revealed the therapeutic significance of numerous phytochemicals ( Table 1 ).…”