A Structurally Characterized Lycium barbarum Polysaccharide Protects Against Retinal Degeneration Through Nrf2...

Retinal degeneration is characterized by progressive photoreceptor loss driven by oxidative stress and chronic inflammation, yet effective mutation-independent therapeutic strategies remain limited. Lycium barbarum polysaccharides (LBPs) possess antioxidant and anti-inflammatory activities; however, the structural features responsible for their retinal protective effects remain poorly defined. In this study, crude LBP was fractionated by DEAE-cellulose ion-exchange chromatography, and the most bioactive fraction, LBPF2, was identified using H₂O₂-injured 661W cone photoreceptor-like cells. LBPF2 was subsequently characterized by high-performance anion-exchange chromatography, SEC-MALLS-RI, GC-MS methylation analysis, and one- and two-dimensional NMR spectroscopy, and its protective effects were evaluated in H₂O₂-treated 661W cells and rd10 mice. LBPF2 was identified as a homogeneous glucose-rich polysaccharide with an average molecular weight of approximately 41 kDa and a backbone mainly composed of →4)-α-D-Glcp-(1→ and →4,6)-α-D-Glcp-(1→ residues. LBPF2 reduced oxidative stress, inflammation, and apoptosis in H₂O₂-treated 661W cells, preserved retinal morphology, improved electroretinographic responses and partial retention of rhodopsin immunoreactivity relative to untreated rd10 mice, and restored redox homeostasis in rd10 mice. Pharmacological inhibition of Nrf2 using ML385 attenuated these protective effects, supporting the involvement of Nrf2/HO-1 signaling. Collectively, these findings identify LBPF2 as a structurally characterized neuroprotective polysaccharide that mitigates retinal degeneration through coordinated regulation of oxidative stress and inflammation and highlight its therapeutic potential for retinal degenerative diseases.