Green Synthesized Gold Nanoparticles Using Naringin and Naringenin: Characterization, Biological Activities, and Cytogenotoxicity

Background/Objectives: The green synthesis of gold nanoparticles (AuNPs) using plant-derived flavonoids offers a sustainable alternative to traditional methods. This study aimed to synthesize, characterize, and evaluate the biological activities and cytogenotoxicity of AuNPs functionalized with naringin (NG) and its aglycone, naringenin (NGN). Methods: Synthesis was optimized by varying pH, HAuCl4 concentration, reagent ratios, temperature, and stirring time. The resulting AuNPs-NG and AuNPs-NGN were characterized via Ultraviolet–Visible (UV–Vis) Spectroscopy, Fourier-Transform Infrared (FTIR) Spectroscopy, Dynamic Light Scattering (DLS), and Scanning Transmission Electron Microscopy with Energy-Dispersive X-ray Spectroscopy (STEM-EDX). Biological potential was assessed through five antioxidant assays, alpha-amylase and alpha-glucosidase inhibition, and antimicrobial screening. Cytogenotoxicity was evaluated using the Allium cepa root meristem model. Results: Optimal synthesis occurred at pH 10 for both flavonoids (NG at 40 °C, NGN at 20 °C). STEM revealed AuNPs-NG were smaller (54.64 ± 13.15 nm) and more polydisperse than AuNPs-NGN (135.52 ± 23.85 nm). Both nanoformulations exhibited superior antioxidant and antidiabetic activities compared to free precursors, with AuNPs-NGN showing the highest potency in inhibiting lipoxygenase (LOX) (EC50 = 9.58 ± 0.74 µg/mL). No antimicrobial activity was detected. In the Allium cepa test, both AuNPs induced concentration-dependent reduction in the mitotic index and triggered predominantly aneugenic chromosomal abnormalities. Conclusions: NG and NGN successfully act as reducing and stabilizing agents for AuNPs, with NGN providing enhanced biological efficacy alongside larger particle sizes. While these biogenic AuNPs show significant therapeutic potential as antioxidant and antidiabetic agents, their concentration-dependent cytogenotoxicity must be carefully considered for biomedical applications.