Preparation of Curcumin-Loaded Spinacia oleracea L.-Derived Exosome-Like Nanovesicles and Their Role in Alleviating Neuroinflammatory Damage

Objective: To investigate the protective effect of curcumin (Cur)-loaded Spinacia oleracea L.-derived exosome-like nanovesicles (SL-ELNs) against neuroinflammatory damage in neural cells. Methods: SL-ELNs were isolated and purified from S. oleracea L. using high-speed centrifugation combined with ultrafiltration, and their structure and composition were characterized. Cur was encapsulated into SL-ELNs to prepare Cur@SL-ELNs, and the encapsulation efficiency of Cur was analyzed using high-performance liquid chromatography (HPLC). The release rate of Cur was evaluated using an in vitro simulated digestion model. The hydrodynamic size, zeta potential, Rose Bengal adsorption capacity, and mucin affinity of Cur@SL-ELNs were measured at different pH values. Laser confocal microscopy (LCM) was used to monitor the uptake of Cur@SL-ELNs by mouse BV-2 microglial cells, and the impact of Cur@SL-ELNs on BV-2 cell proliferation was assessed. The effects of Cur@SL-ELNs and Cur on cytokine secretion levels in lipopolysaccharide (LPS)-challenged BV-2 cells were compared using an enzyme-linked immunosorbent assay (ELISA). Results: SL-ELNs were cup-shaped nanovesicles capable of achieving complete encapsulation of Cur. Cur@SL-ELNs remained stable in saliva and gastric acid but released Cur slowly upon exposure to intestinal fluid, with a release rate of (92.1 ± 4.1)%. Cur@SL-ELNs exhibited favorable adaptive surface properties, facilitating their uptake by BV-2 cells. At concentrations up to 200 ng/mL, Cur@SL-ELNs showed good biocompatibility, repairing LPS-induced damage to BV-2 cells and promoting their growth. Compared with free Cur, Cur@SL-ELNs (100 ng/mL) significantly inhibited the secretion of interleukin-6 (IL-6) and interferon-γ (IFN-γ), while markedly promoting the secretion of IL-10, thereby reducing LPS-induced inflammatory damage to BV-2 cells. Conclusion: Cur@SL-ELNs possess adaptive surface properties that enable steady-state delivery of Cur into BV-2 cells, exhibiting its anti-inflammatory activity and mitigating LPS-induced inflammatory damage, thereby exerting neuroprotective effects.