Green Synthesis, Characterization, and Evaluation of Antimicrobial, Antioxidant, Hepatoprotective, and Nephrocurative Potentials of Zinc Oxide Nanoparticles Derived from Lannea subscorpioidea (Oliv.) Extract.

Abstract

This study investigated the green synthesis, characterization, and biological evaluation of zinc oxide nanoparticles (ZnO NPs) using aqueous leaf extract of Lannea subscorpioidea (Oliv.), a medicinal plant widely used in Northern Nigeria. Two precursor concentrations (0.1 M and 0.01 M Zn(NO₃)₂·6H₂O) were utilized to examine the influence of synthesis parameters on nanoparticle structure and biological function. Characterization through UV – Visible spectroscopy, FTIR, SEM, and XRD confirmed successful formation and concentration-dependent variation in particle features. The UV–Vis spectra of the 0.1 M sample exhibited two major absorption peaks at 272 nm (A = 9.99) and 335 nm (A = 7.50), while the 0.01 M sample showed weaker peaks at 254 nm (A = 2.50), 222 nm (A = 0.65), and 205 nm (A = 0.53), confirming nanoparticle formation and size-dependent optical behavior. FTIR analysis revealed strong absorption bands at 2478, 2560, 1838, and 1086 cm?¹ for 0.1 M, and at 3979, 3752, 2028, and 480 cm?¹ for 0.01 M, corresponding to O–H, C=O, N–H, and Zn–O stretching vibrations. These indicate the involvement of hydroxyl, amide, and carbonyl groups from phytochemicals in nanoparticle reduction and stabilization. SEM micrographs revealed rod-like nanostructures (average length 80–120 nm, diameter 25–40 nm) for the 0.1 M sample and aggregated spherical clusters (diameter 60–90 nm) for the 0.01 M sample, suggesting that precursor concentration governs nanoparticle morphology and aggregation. XRD analysis confirmed hexagonal wurtzite crystalline structure, with average crystallite sizes of 20–30 nm. Quantitative phase analysis showed ZnO phase purity of 81.5% (ZnO) with minor muscovite (18%) and chlorargyrite (1.7%) in the 0.1 M sample, and 39.5% ZnO, 56% quadratite, and 6% muscovite in the 0.01 M sample. Biological assays demonstrated potent antimicrobial, antioxidant, hepatoprotective, and nephrocurative activities of the biosynthesized ZnO NPs. The 0.1 M ZnO NPs exhibited stronger inhibition against Staphylococcus aureus (18.5 ± 0.4 mm) and Escherichia coli (17.2 ± 0.3 mm), higher antioxidant efficiency (DPPH IC50= 38.6 µg/mL), and greater organ protection, with significant restoration of ALT, AST, creatinine, and urea levels in CCl₄- and gentamicin-induced toxicity models. The 0.01 M nanoparticles showed moderate activity, attributed to larger size and lower crystallinity. Overall, the study establishes Lannea subscorpioidea as an efficient biogenic agent for synthesizing high-purity, bioactive ZnO nanoparticles. The 0.1 M precursor produced optimal nanostructures with enhanced physicochemical and biomedical properties, demonstrating potential applications in infection control, oxidative stress management, and organ protection. Further studies on toxicity, molecular mechanisms, and nanoformulation optimization are recommended to support clinical and industrial applications.