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Aurantiochytrium sp. is an emerging alternative source of polyunsaturated fatty acids (PUFAs), docosahexaenoic acid (DHA), and squalene, playing an important role in the phasing out of traditional fish sources for these compounds. Novel lipid extraction techniques with a focus on sustainability and low environmental footprint are being developed for this organism, but the exploration of other added-value compounds within it is still very limited. In this work, a combination of novel green extraction techniques (high hydrostatic pressure extraction (HPE) and supercritical fluid extraction (SFE)) and traditional techniques (organic solvent Soxhlet extraction and hydrodistillation (HD)) was used to obtain lipophilic extracts of Aurantiochytrium sp., which were then screened for antioxidant (DPPH radical reduction capacity and ferric-reducing antioxidant potential (FRAP) assays), lipid oxidation protection, antimicrobial, anti-aging enzyme inhibition (collagenase, elastase and hyaluronidase), and anti-inflammatory (inhibition of NO production) activities. The screening revealed promising extracts in nearly all categories of biological activity tested, with only the enzymatic inhibition being low in all extracts. Powerful lipid oxidation protection and anti-inflammatory activity were observed in most SFE samples. Ethanolic HPEs inhibited both lipid oxidation reactions and microbial growth. The HD extract demonstrated high antioxidant, antimicrobial, and antiinflammatory activities making, it a major contender for further studies aiming at the valorization of Aurantiochytrium sp. Taken together, this study presents compelling evidence of the bioactive potential of Aurantiochytrium sp. and encourages further exploration of its composition and application.

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Alaria esculenta is a brown seaweed farmed in many European countries for its biomass rich in useful bio compounds. This study aimed to identify the optimal growing season to maximise biomass production and quality. The seeded longlines of the brown seaweed were deployed in the southwest of Ireland in October and November 2019 and samples of the biomass were harvested in different dates, between March and June 2020. Biomass gain and composition, phenolic and flavonoid content (TPC and TFC) and biological activities (antioxidant and anti-hypertensive activities) of seaweed extracts prepared with Alcalase were evaluated. The biomass production was significantly higher for the line deployed in October (>20 kg·m−1). In May and June, an increasing amount of epiphytes was observed on the surface of A. esculenta. The protein content of A. esculenta varied between 11.2 and 11.76% and fat content was relatively low (1.8–2.3%). Regarding the fatty acids profile, A. esculenta was rich in polyunsaturated fatty acids (PUFA), especially in eicosapentaenoic acid (EPA). The samples analysed were very rich in Na, K, Mg, Fe, Mn, Cr and Ni. The content of Cd, Pb Hg was relatively low and below the maximum levels allowed. The highest TPC and TFC were obtained in extracts prepared with A. esculenta collected in March and levels of these compounds decreased with time. In general, the highest radical scavenging activities (ABTS and DPPH), as well as chelating activities (Fe2+ and Cu2+) were observed in early spring. Extracts from A. esculenta collected in March and April presented higher ACE inhibitory activity. The extracts from seaweeds harvested in March exhibited higher biological activity. It was concluded that an earlier deployment allows for maximising growth and harvest of biomass earlier when its quality is at the highest levels. The study also confirms the high content of useful bio compounds that can be extracted from A. esculenta and used in the nutraceutical and pharmaceutical industry.