In Situ Biosynthesis of Reduced Alpha Hematite (α-Fe2O3) Nanoparticles by Stevia Rebaudiana L. Leaf Extract: Insights into Antioxidant, Antimicrobial, and Anticancer Properties

Abstract

In the present study, we utilized <i>Stevia rebaudiana</i> L. (SRLe) extract to in situ biosynthesize nanoscale alpha hematite (α-Fe₂O₃) nanoparticles (NPs) with potent antioxidant, antimicrobial, and anticancer properties. SRLe-α-Fe₂O₃ was characterized using physiochemical analyses, including UV/Vis, FTIR, XRD, DLS, EDX, SEM, and TEM studies. Among tested solvents, CHCl₃/MeOH (2:1 <i>v</i>/<i>v</i>) SRL extract (least polar solvent) contained the highest EY, TPC, and antioxidant capacity of ~3.5%, ~75 mg GAE/g extract, and IC₅₀ = 9.87 ± 0.7 mg/mL, respectively. FTIR confirmed the engagement of coating operation to the colloidal α-Fe₂O₃ NPs. TEM, SEM, and DLS revealed that SRLe-α-Fe₂O₃ has a spherical shape, uniform size distribution with aggregation for an average size of ~18.34 nm, and ζ = -19.4 mV, forming a repulsive barrier that helped to improve stability. The synthesized nanoparticles displayed considerable antibacterial activity against <i>E. coli</i> and <i>S. aureus</i> bacterial growth, and exhibited superior activity against the A549 lung cancer cell lines. These findings indicate that the increased availability of bioactive substances with antioxidant properties of SRLe makes it a potentially interesting material for the preparation of biologically active compounds and green synthesis of nanoparticles.