Astaxanthin-loaded brain-permeable liposomes for Parkinson’s disease treatment via antioxidant and anti-inflammatory responses

Parkinson's disease is a neurodegenerative disorder characterized by cardinal motor symptoms resulting from the loss of dopaminergic neurons in the substantia nigra pars compacta. Although current medications may alleviate its symptoms, Parkinson's disease remains incurable. Astaxanthin is an antioxidant and anti-inflammatory agent; however, its high susceptibility to oxidative degradation and low aqueous solubility limit its therapeutic efficacy. This study aimed to improve the pharmaceutical properties and neuroprotective effects of astaxanthin for Parkinson's disease treatment by using lactoferrin-conjugated astaxanthin-loaded liposomes (Lf-ASX-LPs). We successfully formulated Lf-ASX-LPs with high encapsulation efficiency (97.6%) and favorable physical characteristics (diameter: 109.8 ± 1.1 nm; polydispersity index: 0.18 ± 0.01; zeta potential: - 9.5 ± 1.1 mV). Lf-functionalized liposomes demonstrated enhanced cellular uptake and permeation in a Transwell® study, showing a 16.7-fold higher internalization in SH-SY5Y cells over 24 h than those without Lf conjugation. Additionally, Lf functionalization enhanced brain penetration ability, as demonstrated by a biodistribution study using nude mice, compared to LPs without Lf conjugation. In vitro, Lf-ASX-LPs reduced cell loss by 20.1% and oxygen species by 30.0%, ameliorated the reduction in mitochondrial membrane potential under 1-methyl-4-phenylpyridinium-induced toxicity by 40.1%, and reduced extracellular nitric oxide levels under lipopolysaccharide-induced toxicity by 32.0%, indicating cytoprotective and antioxidant effects. In a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinson's disease mouse model, treatment with Lf-ASX-LPs resulted in 5.0-, 3.1-, and 5.6-fold increases in dopamine levels, TH+ fiber density, and TH+ neurons, respectively, restoring dopaminergic neuron damage. The developed formulation also alleviated behavioral impairment and neuroinflammation, reducing astrocyte and microglial activation in the striatum and substantia nigra of the MPTP-treated animals. Thus, our formulation of Lf-ASX-LPs represents a promising strategy for providing neuroprotection and retarding Parkinson's disease progression.