GREEN SYNTHESIS OF IRON OXIDE NANOPARTICLES FROM PLECTRANTHUS AMBOINICUS AND THEIR WIDE RANGE OF BIOMEDICAL APPLICATIONS

Objective: Green synthesis of metal nanoparticles provides an environmentally friendly approach in comparison with the chemical method. Iron oxide nanoparticles (FeONPs) have potential biomedical applications such as antimicrobial, antioxidant, and anti-inflammatory activities. The goal of the current study was to synthesize FeONPs using the leaf extract of Plectranthus amboinicus and to assess the biological activities. Methods: FeONPs were prepared in a green reduction and stabilization method using aqueous extracts of P. amboinicus leaves. The formation of FeONPs was initially qualitatively identified through colorimetry and additionally identified using ultraviolet (UV)-visible spectroscopy, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). Antimicrobial testing was conducted against Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus mutans, Aggregatibacter actinomycetemcomitans, and Candida albicans using minimum inhibitory concentrations (MIC) and time-kill methods. The antioxidant property of the synthesized FeONPs was evaluated using the 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay. The anti-inflammatory property was analyzed by protein denaturation inhibition assays utilizing bovine serum albumin and egg albumin models. The cytotoxicity as well as the toxic properties of FeONPs were analyzed by brine shrimp (Artemia salina) lethality bioassays. Results: The emergence of a clear color transition from dark brown to light brownish-orange signified nanoparticle development, accompanied by a distinctive UV–Visible Spectroscopy absorption wavelength at 395 nm. XRD pattern verification demonstrated the nanocrystalline and phase-pure quality of FeONPs, measuring 10–12 nm. FTIR pattern matching further demonstrated surface modification by OH, aromatic, and phenolic moieties. The MIC range was 25–100 μg/mL, demonstrating broad-spectrum antibacterial activity, considerable antioxidant activity, and moderate anti-inflammatory activity. Cytotoxicity studies also exhibited moderate cell toxicity with LC50 = 8 μg/mL. Conclusion: Green-synthesized FeONPs using P. amboinicus demonstrated stability, multifunctional bioactivity, and promising antimicrobial, antioxidant, and anti-inflammatory properties, highlighting their potential for further in vivo biomedical applications.