Nose-to-brain delivery of berberine-loaded nanoemulsion: Amelioration of brain targeting, behavioral, pharmacokinetic, and biodistribution insights for Alzheimer's intervention.

Berberine (BER), a benzylisoquinoline alkaloid, has garnered attention for its multifaceted pharmacological properties, including pronounced antioxidant, anti-inflammatory, and neuroprotective effects. Despite its therapeutic potential in neurodegenerative disorders, including Parkinson's disease, cerebral ischemia, and epilepsy, its clinical translation in Alzheimer's disease (AD) is hindered by poor aqueous solubility, limited systemic bioavailability, and restricted blood-brain barrier (BBB) permeability. This study aimed to overcome these limitations by formulating a BER-loaded nanoemulsion (BER-NE) for intranasal (IN) delivery to achieve direct nose-to-brain (N2B) targeting. The optimized NE exhibited a droplet size of 138.5 ± 0.96 nm and a polydispersity index (PDI) of 0.203 ± 0.007, indicating a monodisperse system. The BER-NE demonstrated a drug content of 99.62 ± 1.02%, confirming efficient drug incorporation. In vitro studies on SH-SY5Y neuroblastoma cells demonstrated that BER-NE reduced reactive oxygen species (ROS) levels by 2.09-fold and restored mitochondrial membrane potential (MMP) with a 3.61-fold increase in red/green fluorescence intensity compared to SCOP-induced cells. Further, pharmacokinetic (PK) profiling revealed that IN BER-NE achieved a 3.2- and 3.6-fold increase in brain Cmax compared to BER-SUS IN and BER-NE IV, respectively. The IN BER-NE demonstrated a 1.7- and 1.9-fold increase in %DTE and %DTP compared to the IN SUS, which supports the efficient N2B delivery. Behavioral assessments demonstrated dose-dependent reversal of SCOP-induced cognitive, depressive, and motor impairments. Additionally, treatment with HD BER-NE and MD BER-NE via the IN route markedly reduced the nitrite accumulation by 4.3- and 3.5-fold compared to the SCOP group, indicating attenuation of nitrosative stress. Collectively, these findings underscore the potential of IN BER-NE as a targeted and non-invasive therapeutic strategy for the management of AD.