Natural Astaxanthin Is a Green Antioxidant Able to Counteract Lipid Peroxidation and Ferroptotic Cell Death.

Astaxanthin is a red orange xanthophyll carotenoid produced mainly by microalgae but which can also be chemically synthesized. As demonstrated by several studies, this lipophilic molecule is endowed with potent antioxidant properties and is able to modulate biological functions. Unlike synthetic astaxanthin, natural astaxanthin (NAst) is considered safe for human nutrition, and its production is considered eco-friendly. The antioxidant activity of astaxanthin depends on its bioavailability, which, in turn, is related to its hydrophobicity. In this study, we analyzed the water-solubility of NAst and assessed its protective effect against oxidative stress by means of different approaches using a neuroblastoma cell model. Moreover, due to its highly lipophilic nature, astaxanthin is particularly protective against lipid peroxidation; therefore, the role of NAst in counteracting ferroptosis was investigated. This recently discovered process of programmed cell death is indeed characterized by iron-dependent lipid peroxidation and seems to be linked to the onset and development of oxidative-stress-related diseases. The promising results of this study, together with the "green sources" from which astaxanthin could derive, suggest a potential role for NAst in the prevention and co-treatment of chronic degenerative diseases by means of a sustainable approach.

Extraction of astaxanthin from Haematococcus pluvialis with hydrophobic deep eutectic solvents based on oleic acid.

Three novel hydrophobic deep eutectic solvents (DESs) based on oleic acid and terpenes (thymol, dl-menthol, and geraniol) were prepared, characterized, and used to extract astaxanthin from the microalga Haematococcus pluvialis without any pre-treatment of the cells. The three DES were composed of Generally Recognized As Safe (GRAS) and edible ingredients. All the tested DESs gave astaxanthin recovery values of about 60 and 30% in 6 h if applied on freeze-dried biomass or directly on algae culture, respectively. The carotenoid profile was qualitatively identical to what was obtained by using traditional organic solvents, regardless of the DES used; the monoesters of astaxanthin with C18-fatty acids were the main compounds found in all the carotenoid extracts. The thymol:oleic acid DES (TAO) could preserve astaxanthin content after prolonged oxidative stress (40% of the astaxanthin initially extracted was still present after 13.5 h of light exposure), thanks to the superior antioxidant properties of thymol. The capacity of improving astaxanthin stability combined with the intrinsic safety and edibility of the DES components makes the formulation astaxanthin-TAO appealing for the food ingredients/additives industry.