Development and Characterization of Chitosan Nanoparticles Containing Quercetin-β-Cyclodextrin Inclusion Complex for Improved Solubility, Brain Targeting, and Neuroprotective Potential Against Epilepsy.

The present study focuses on developing and optimising chitosan nanoparticles containing quercetin-β-cyclodextrin inclusion complex (QNPs) using the nanoprecipitation method to enhance quercetin's solubility, stability, and bioavailability. A comprehensive optimization study revealed that Batch B6, which utilized ethanol as the solvent, poloxamer 188 as the stabilizer, and chitosan at a concentration of 0.2% (w/v), exhibits optimal characteristics required for providing a stable colloidal system. The prepared nanoparticles were characterized for their physicochemical properties using FTIR, DSC, X-ray Diffraction, and SEM, which confirmed the successful inclusion of quercetin within the β-cyclodextrin complex and the reduction in crystallinity. In-vitro drug release studies demonstrated a controlled release profile for QNPs compared to free quercetin and the inclusion complex. Pharmacokinetic evaluation in mice via oral administration revealed a significant enhancement in systemic circulation and brain uptake, with QNPs showing a peak plasma concentration of 6.5 µg/mL at 2 h and a brain concentration of 3.5 µg/g at 4 h, indicating improved bioavailability and prolonged retention. In the Pentylenetetrazole and Kainic acid-induced epilepsy mice model, QNP significantly reduced seizure duration, frequency of seizures, and severity scores favoured the QNP formulation over free quercetin. QNPs also exhibited a significant neuroprotective effect by enhancing antioxidant enzyme levels such as superoxide dismutase, catalase, and glutathione reductase in brain tissue. Furthermore, Na⁺/K⁺-ATPase activity was significantly preserved in QNP-treated groups, indicating membrane stability and reduced neuronal excitability. These findings suggest that QNPs offer a promising strategy for enhancing quercetin's therapeutic efficacy in neurological disorders such as epilepsy.