Eco-Friendly Synthesis of Bioactive Silver Nanoparticles Using Astragalus fasciculifolius Extracts: Regional Phytochemical Variation and Biomedical Potential

Objective: Green synthesis of nanoparticles has emerged as a promising strategy in material science and nanotechnology. In this study, silver nanoparticles (AgNPs) were synthesized through a cost-effective, environmentally friendly, and highly efficient process. Bioreduction was carried out at room temperature using aqueous root and gum extracts of Anzaroot (Astragalus fasciculifolius Bioss). Methods: Roots and gum of A. fasciculifolius were collected from six locations in Sistan–Baluchestan Province (Table ۱). Aqueous extracts (۱۰ g/۱۰۰ mL) were prepared and analyzed for total phenolics (Folin–Ciocalteu), flavonoids (AlCl₃), and carbohydrates (phenol–sulfuric acid). AgNPs were biosynthesized using ۱, ۳, and ۵ mM AgNO₃ solutions, with ۱ mM identified as optimal. Nanoparticles were characterized by UV–Vis spectroscopy, TEM, and XRD. Antioxidant activity (DPPH assay) and antimicrobial activity (MIC/MBC) were assessed against four bacterial strains. GC–MS (Agilent ۷۸۹۰A) was performed using an HP-۵ MS column. Results: GC–MS analysis revealed pronounced regional differences in gum composition: Khash samples were rich in aliphatic hydrocarbons, Sarava samples contained pharmaceutical-like compounds (pilocarpine, gabapentin derivatives), and Sarbaz gum showed unique nitrogenous constituents (۱۷.۵۲% urea derivatives), suggesting environmental adaptation. ANOVA indicated significant location-dependent differences (p<۰.۰۱) in phenolic content (mean ۳۲.۴۱ mg GAE/g), with Poshtkuh showing the highest accumulation (۴۲.۶۱ mg GAE/g). Flavonoids ranged from ۰–۲.۰ mg QE/g, while carbohydrate levels (mean ۳۶۶.۹۳ mg GE/g) displayed habitat-specific variation (p<۰.۰۱). Biosynthesized AgNPs exhibited surface plasmon resonance at ۴۰۰–۵۰۰ nm and crystalline peaks at ۳۸°, ۴۳°, ۶۴°, and ۷۷.۳° (XRD). TEM confirmed spherical AgNPs (۵–۵۰ nm), with gum-derived nanoparticles (۲۳.۲۹ nm) demonstrating superior DPPH scavenging (۹۸.۴۰% at ۵۰۰ μg/mL) compared with root-derived AgNPs (۸۱.۴۱%). Antimicrobial assays (۴۰۰ μg/mL) showed enhanced Gram-negative inhibition (MIC ۳.۱۲–۵۰ μg/mL), whereas crude extracts were more active against Gram-positive strains. Conclusion: This study highlights the diverse phytochemistry, regional variability, and bioactivity of A. fasciculifolius gum, underscoring its potential applications in antimicrobial, antioxidant, and nanomedicine research. The biosynthesized AgNPs demonstrated potent antioxidant and Gram-selective antibacterial properties. Further studies should investigate environmental drivers of metabolite production, elucidate pharmacological mechanisms, and develop scalable AgNP synthesis for therapeutic use.

کلیدواژه ها:

Anzaroot (Astragalus fasciculifolius Bioss) ، Bacillus cereus ، Escherichia coli ، Pseudomonas aeruginosa ، Staphylococcus aureus