Enhancement of antioxidative activity of astaxanthin by combination with an antioxidant capable of forming intermolecular interactions

More Than Pigments: The Potential of Astaxanthin and Bacterioruberin-Based Nanomedicines

Carotenoids are natural products regulated by the food sector, currently used as feed dyes and as antioxidants in dietary supplements and composing functional foods for human consumption. Of the nearly one thousand carotenoids described to date, only retinoids, derived from beta carotene, have the status of a drug and are regulated by the pharmaceutical sector. In this review, we address a novel field: the transformation of xanthophylls, particularly the highly marketed astaxanthin and the practically unknown bacterioruberin, in therapeutic agents by altering their pharmacokinetics, biodistribution, and pharmacodynamics through their formulation as nanomedicines. The antioxidant activity of xanthophylls is mediated by routes different from those of the classical oral anti-inflammatory drugs such as corticosteroids and non-steroidal anti-inflammatory drugs (NSAIDs): remarkably, xanthophylls lack therapeutic activity but also lack toxicity. Formulated as nanomedicines, xanthophylls gain therapeutic activity by mechanisms other than increased bioavailability. Loaded into ad hoc tailored nanoparticles to protect their structure throughout storage and during gastrointestinal transit or skin penetration, xanthophylls can be targeted and delivered to selected inflamed cell groups, achieving a massive intracellular concentration after endocytosis of small doses of formulation. Most first reports showing the activities of oral and topical anti-inflammatory xanthophyll-based nanomedicines against chronic diseases such as inflammatory bowel disease, psoriasis, atopic dermatitis, and dry eye disease emerged between 2020 and 2023. Here we discuss in detail their preclinical performance, mostly targeted vesicular and polymeric nanoparticles, on cellular models and in vivo. The results, although preliminary, are auspicious enough to speculate upon their potential use for oral or topical administration in the treatment of chronic inflammatory diseases.

Astaxanthin delays brain aging in senescence-accelerated mouse prone 10: inducing autophagy as a potential mechanism

Brain aging is a complex biological process often associated with a decline in cognitive functions and motility. Astaxanthin (AST) is a strong antioxidant capable of crossing the blood-brain barrier. The effect of AST on brain aging and its physiological and molecular mechanism are still unclear. The study aimed to investigate whether AST from AstaReal A1010 improved brain aging by inducing autophagy in SAMP10 mice. Different concentrations of AstaReal A1010 were intragastrically administered to 6-month-old SAMP10 mice for 3 months. The results demonstrated that AST delayed age-related cognitive decline, motor ability and neurodegeneration, upregulated the expression levels of autophagy-related genes beclin-1 and LC3 in the brain. It may induce autophagy by regulating IGF-1/Akt/mTOR and IGF-1/Akt/FoxO3a signaling. Treatment with autophagy inhibitor 3-methyladenine (3MA) partly reversed the anti-aging effect of AST. In conclusion, our findings suggest that AST may induce autophagy by regulating IGF-1/Akt/mTOR and IGF-1/Akt/FoxO3a signaling, thereby delaying age-related neurodegeneration and cognitive decline in SAMP10 mice.

Protective Effect of Antioxidative Liposomes Co-encapsulating Astaxanthin and Capsaicin on CCl4-Induced Liver Injury

Our previous study reported that co-encapsulation of potent antioxidants astaxanthin (Asx) and capsaisin (Cap) into liposomes brought about synergistically higher antioxidative activity than the calculated additive activity of each single antioxidant encapsulating liposome. Based on the previous computational chemistry analysis, the synergistic effect was revealed to be resulted from intermolecular interactions between Asx, especially 3R,3'R-form of Asx stereoisomer (Asx-R), and Cap, by which changes of electronic states of the polyene moiety of Asx-R were induced. Although liposomes co-encapsulating Asx-R and Cap (Asx-R/Cap-Lipo) at an optimal ratio clearly showed synergistic antioxidative activity in vitro, it is unclear whether the effective antioxidative activity derived from intermolecular interaction between Asx-R and Cap is also exerted in vivo. Therefore, in this study, we investigated therapeutic potential of Asx-R/Cap-Lipo as an antioxidant formulation in vivo. For this purpose, we employed carbon tetrachloride (CCl₄)-induced acute liver injury rat model, since CCl₄ is known to cause oxidative damage in liver. CCl₄ administration significantly increased the levels of aspartate transaminase (AST) and alanine aminotransferase (ALT). Intravenous combined administration of liposomes encapsulating Asx-R (Asx-R-Lipo) and liposomes encapsulating Cap (Cap-Lipo) significantly decreased CCl₄-induced increase of AST and ALT levels. Importantly, the treatment with Asx-R/Cap-Lipo tended to show higher protective effect on acute liver injury than combined treatment with Asx-R-Lipo plus Cap-Lipo. These results suggest that co-encapsulated Asx-R and Cap in liposomal membranes could exert more effective antioxidative activities in vivo, and that Asx-R/Cap-Lipo would be a hopeful antioxidant formulation for treating reactive oxygen species-related diseases.