Pressurized liquids extraction for obtaining microalgae extracts enriched in carotenoids with anti-inflammatory and neuroprotective effects

Abstract

Microalgae are considered as an untapped reservoir for potential functional ingredients and high added-value compounds with diverse application in cosmetics, pharmaceutical and food industries. Some of these bioactive compounds include polyunsaturated fatty acids, peptides, polyphenols, phytosterols or carotenoids. Regarding carotenoids, these lipophilic compounds have been associated with an extensive list of healthpromoting effects, including anti-inflammatory, neuroprotective or antioxidant properties, which emphasizes their potential value. In this study, the recovery of carotenoids from diverse microalgae, including extracts from Haematococcus pluvialis, Nannochloropsis oceanica, Tisochrysis lutea and Porphyridium cruentum, was performed using pressurized liquid extraction at semi-pilot scale, using the same optimum extraction conditions as obtained at lab-scale. The extracts were chemically characterized by reversed-phase high-performance liquid chromatography with diode array detection (RP-HPLC-DAD) and then, these were evaluated through a battery of in vitro neuroprotective assays in an effort to estimate their potential against neurological disorders. Results indicated that microalgae extracts (obtained at semi-pilot scale) had similar carotenoid profiles compared to extracts obtained at lab-scale, although higher yields were achieved due to the additional extraction cycle. All microalgae exerted a moderate and selective cholinesterase inhibitory potential, as well as high antioxidant and anti-inflammatory capacities, highlighting N. oceanica and T. lutea extracts. In parallel, cytotoxicity tests of the microalgae extracts were performed in different cell culture models, together with an in vitro evaluation of their anti-inflammatory capacity in THP-1 cells. In this regard, N. oceanica extract showed the highest inhibition of proinflammatory cytokine release, indicating that this microalga extract could be the most promising neuroprotective agent.