Naringenin-loaded nanoparticles ameliorate scopolamine-induced neurotoxicity

Background Naringenin has shown attractive neuroprotective effects; however, it is characterized by low oral bioavailability. Naringenin-loaded nanoparticles (Nar-NPs) were prepared for enhanced delivery, and their effects in scopolamine-induced cholinergic hypofunction model were tested, either alone or in combination with donepezil. Methods Nar-NPs were developed via solvent evaporation with Span-80/Tween-80 and then characterized for morphological characteristics (TEM), hydrodynamic size/PDI, and zeta potential (DLS/ELS). Encapsulation efficiency (EE%), drug loading (DL%), and stability in simulated physiological buffer were also determined. Three different batches were used to evaluate the reproducibility of the formulation. Male mice were injected with scopolamine (3 mg/kg, i.p.) and orally administered Nar-NPs (37.75 mg/kg) or Nar-NPs combined with donepezil (10 mg/kg). Results were evaluated as Morris Water Maze, oxidative stress and inflammatory markers, lipid profile, qRT-PCR, and histopathology. Molecular docking analyses examined possible bonds of naringenin interaction with GABRA5α and GSK-3β as hypothesis-generating results. Results Nar-NPs were spherical in shape (~ 95 nm), of monodisperse size (PDI < 0.2) and negatively charged (ζ ≈ -28.5mV). The formulation showed high encapsulation efficiency (EE% = 89.2 ± 3.1%), demonstrated good colloidal stability in phosphate buffer (pH 7.4) over 24 h, and exhibited a sustained drug release profile as well with sustained release profile (Korsmeyer-Peppas, n ≈ 0.56). The batch-to-batch reproducibility of ζ was high (− 28.47, -28.71, − 28.52mV; mean = − 28.57 ± 0.13mV; CV% ≈ 0.44%). In vivo, Nar-NP attenuated scopolamine-induced deficits as evidenced by the amelioration of acquisition and probe trial performance, normalization in levels of antioxidant defenses, reduction in neuroinflammatory mediators, and reinforcement of hippocampal architecture. The combination with donepezil produced effects greater than either monotherapy alone, suggesting potential additive or synergistic interaction. Docking indicated reasonable binding to GABRA5α and GSK-3β, but this is exploratory and needs validation ex vivo/in vivo for the mechanism of action. Conclusions Nar-NPs are a predictable, stable, and bioavailable formulation with multidomain neuroprotective potential in a cholinergic impairment model. Since the reversible model we use mimics acute cholinergic dysfunction with associated oxidative and inflammatory sequelae rather than the progressive proteinopathies (amyloid-β accumulation, tau hyperphosphorylation) and chronic neurodegeneration seen in Alzheimer’s disease, the current findings ought to be interpreted as an example of symptom-relevant rather than disease-modifying neuroprotection. As such, the multi-domain therapeutic potential implied by our molecular and histopathological endpoints must be tested stringently in chronic, pathology-induced models (e.g., transgenic APP/PS1 or 3xTg-AD mice) for determining translational relevance to Alzheimer’s disease.