Bacterioruberin (C₅₀ Carotenoid): Nutritional and Biomedical Potential of a Microbial Pigment

Haloarchaea are moderate and extreme halophilic microorganisms inhabiting hypersaline environments characterised by high ionic and oxidative stress due to extremely high salt concentrations and high incidence of UV radiation (mainly in spring and summer). To be alive and metabolically active under these harsh conditions, haloarchaeal strains have developed molecular adaptations, like hyperpigmentation. Among the carotenoids produced by haloarchaeal species, the C₅₀ carotenoid called bacterioruberin (BR) and its derivatives, monoanhydrobacterioruberin and bisanhydrobacterioruberin, are the predominant natural pigments produced. This review aims to highlight the most significant characteristics of BR and their derivatives, as well as a description of the biological activities already reported that could provide benefits for human health, including antitumoral, immunomodulatory, antioxidant, skin protectant, antilipidemic, antiglycemic, and anti-atrophic effects, in addition to showing potential positive effects on sperm cells cryopreservation. Overall, C₅₀ carotenoids are fascinating natural biomolecules that could be utilised in processed food and nutraceuticals or as tools in the context of new strategies and/or pharmaceutical formulations to combat various human diseases or metabolic disorders.