Green synthesis of nanoselenium by Ferula assa-foetida (L.) root extract: Docking study, antimicrobial activity, and its role as a biostimulant in Vicia faba (L.) seedlings

Green synthesis of selenium nanoparticles (SeNPs) using Ferula assa-foetida L. root extract offers an eco-friendly approach for biomedical and agricultural applications by leveraging plant metabolites. This study characterized SeNPs, evaluated antimicrobial and antioxidant properties of the extract and SeNPs, assessed SeNPs’ biostimulant effects on Vicia faba L. seed germination, and explored bioactivity mechanisms via molecular docking. SeNPs, averaging 90.4 nm, were characterized using UV-Vis spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), zeta sizer, and zeta potential. SeNPs exhibited notable antimicrobial activity against Escherichia coli, Staphylococcus aureus, and Candida albicans. Inhibition zones were: E. coli (SeNPs: 18 mm; extract: 15 mm), S. aureus (SeNPs: 15 mm; extract: 12 mm), and C. albicans (SeNPs: 13 mm; extract: 17 mm). Molecular docking linked these to SeNPs’ binding to E. coli RNA polymerase (3LU0, -3.3224 kcal/mol), S. aureus RNA polymerase (4EDG, -3.0732 kcal/mol), and C. albicans CYP51 (5FSA, -3.5097 kcal/mol), indicating transcription and fungal membrane disruption. The extract exhibited strong antioxidant capacity via DPPH assay (IC50: 37.38 µg/mL), while SeNPs showed moderate activity (IC50: 338.4 µg/mL), correlated with superoxide dismutase binding (2SOD, -2.0912 kcal/mol), enhancing radical scavenging. Seed priming with low SeNP concentrations (1 and 5 µM) increased Vicia faba shoot length (56.66%, 30%) and root length (4 to 8.5 cm at 5 µM), with elevated sugars (57.06% at 1 µM) and proteins (33.1% at 1 µM), tied to auxin receptor TIR1 binding (2P1Q, -3.3108 kcal/mol), promoting growth signaling. Ferula assa-foetida extract and SeNPs demonstrated antimicrobial efficacy against multidrug-resistant pathogens, with the extract’s phytochemicals supporting green SeNPs synthesis. SeNPs outperformed the extract against E. coli and S. aureus, while the extract excelled against C. albicans. Low SeNP concentrations enhanced Vicia faba growth, promising for agriculture, but high doses inhibited growth, requiring caution. Molecular docking suggested mechanisms needing validation. Further phytochemical studies were recommended for medical and agricultural applications, pending clinical testing.