The marine environment is a generous source of biologically active compounds useful for human health. In 50 years, about 25,000 bioactive marine compounds have been identified, with an increase of 5% per year. Peculiar feature of algae and plants is the production of secondary metabolites, such as polyphenols, synthesized as a form of adaptation to environmental stress. Posidonia oceanica is a Mediterranean endemic and dominant seagrass and represents a biologically, ecologically and geologically important marine ecosystem. Within this study, methanolic and ethanolic extracts were generated from fresh and dried Posidonia oceanica leaves, with the aim to employ and valorize the beach cast leaves. The best yield and antioxidant activity (polyphenols content equal to 19.712 ± 0.496 mg GAE/g and DPPH IC50 of 0.090 µg/µL.) were recorded in 70% ethanol extracts (Gd-E4) obtained from leaves dried for two days at 60 °C and ground four times. HPLC analyses revealed the presence of polyphenols compounds (the most abundant of which was chicoric acid) with antioxidant and beneficial properties. Bioactive properties of the Gd-E4 extracts were evaluated in vitro using fibroblast cells line (HS-68), subjected to UV induced oxidative stress. Pre-treatment of cells with Gd-E4 extracts led to significant protection against oxidative stress and mortality associated with UV exposure, thus highlighting the beneficial properties of antioxidants compounds produced by these marine plants against photo damage, free radicals and associated negative cellular effects. Beach cast leaves selection, processing and extraction procedures, and the in vitro assay results suggested the potentiality of a sustainable approach for the biotechnological exploitation of this resource and could serve a model for other marine resources.

In this study we focused on four taxa of the genus Calendula (C. maritima, C. suffruticosa subsp. fulgida, C. arvensis, and the hybrid between the first two ones), collected in Mediterranean area (Sicily). Six extracts for each species were obtained using solvents with increasing polarity (hexane, ethanol 80%, acetone 70%, and water) and through extraction by supercritical fluids (SFE). It has been observed that the solvent with the highest extraction efficiency was ethanol 80% for all species. However, SFE extracts showed high antioxidant activity comparable to the ethanol 80% extract (polyphenol, DPPH, and reducing power method). These findings were confirmed by in vitro analysis (MTT assay) where it was observed that the tested concentration (24 µg/mL), obtained from ethanol 80% and SFE extracts, showed a protective effect comparable to that induced by a synthetic antioxidant. Extraction with SFE ensured a great selectivity by avoiding the use of toxic organic solvents and thus consisted of a promising technique for sustainable production of Calendula extracts.

The valorization of side streams from fishery and aquaculture value-chains is a valuable solution to address one of the challenges of the circular economy: turning wastes into profit. Side streams produced after filleting of sea cage fattened bluefin tuna (Thunnus thynnus) were analyzed for proximate composition and fatty acid profile to evaluate the possibility of producing tuna oil (TO) as a valuable source of ω-3 polyunsaturated fatty acids (PUFA) and testing its bioactivity in vitro. Ethyl esters of total fatty acids (TFA), obtained from TO, were pre-enriched by urea complexation (PUFA-Ue) and then enriched by short path distillation (SPD) up to almost 85% of the PUFA fraction (PUFA-SPe). The bioactivity of TFA, PUFA-SPe, and ethyl esters of depleted PUFA (PUFA-SPd) were tested in vitro, through analysis of lipid metabolism genes, in gilthead sea bream (Sparus aurata) fibroblast cell line (SAF-1) exposed to oils. TFA and PUFA-SPd upregulated transcription factors (pparβ and pparγ) and lipid metabolism-related genes (D6D, fas, fabp, fatp1, and cd36), indicating the promotion of adipogenesis. PUFA-SPe treated cells were similar to control. PUFA-SPe extracted from farmed bluefin tuna side streams could be utilized in fish feed formulations to prevent excessive fat deposition, contributing to improving both the sustainability of aquaculture and the quality of its products.

Phaeodactylum tricornutum (Bacillariophyta) is a worldwide-distributed diatom with the ability to adapt and survive in different environmental habitats and nutrient-limited conditions. In this research, we investigated the growth performance, the total lipids productivity, the major categories of fatty acids, and the antioxidant content in P. tricornutum subjected for 15 days to nitrogen deprivation (N−) compared to standard culture conditions (N+). Furthermore, genes and pathways related to lipid biosynthesis (i.e., glucose-6-phosphate dehydrogenase, acetyl-coenzyme A carboxylase, citrate synthase, and isocitrate dehydrogenase) and photosynthetic activity (i.e., ribulose-1,5-bisphospate carboxylase/oxygenase and fucoxanthin-chlorophyll a/c binding protein B) were investigated through molecular approaches. P. tricornutum grown under starvation condition (N−) increased lipids production (42.5 ± 0.19 g/100 g) and decreased secondary metabolites productivity (phenolic content: 3.071 ± 0.17 mg GAE g⁻¹; carotenoids: 0.35 ± 0.01 mg g⁻¹) when compared to standard culture conditions (N+). Moreover, N deprivation led to an increase in the expression of genes involved in fatty acid biosynthesis and a decrease in genes related to photosynthesis. These results could be used as indicators of nitrogen limitation for environmental or industrial monitoring of P. tricornutum.

This study aimed to evaluate the antioxidant activity of bioactive compounds extracted from Gracilaria gracilis cultivated in an integrated multi-trophic aquaculture (IMTA) system by different extraction solvents and to investigate the potential capacity of the extracts in cellular systems against environmental pollutants. The global yields, total polyphenol contents, and antioxidant activity were assessed on G. gracilis by DPPH radical scavenging activity, comparing the antioxidant extraction efficiency of the different solvents (ethanol 80%, acetone 70%, N-hexane, and water). Ethanol extract, granted by the highest extractive yield and antioxidant capacity, was tested in vitro in the Sparus aurata fibroblast (SAF-1) cell line to evaluate its protective role against oxidative stress induced by the chemical flame retardant 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47). The results demonstrate that the cells pretreated with G. gracilis extract were protected against oxidative stress and had improved cell viability, cellular antioxidant defense system, and cell cycle control, as demonstrated by the gene expression on some biomarkers related to the cell cycle (p53) and oxidative stress (nrf2, sod, and cat). These results confirm that bioactive compounds obtained from seaweeds cultivated in IMTAs could contribute to producing high-value ingredients that are able to counteract environmental stressors, for the growth of the marine biobased industrial sector and the expansion of new value chains.

Marine plants are a rich source of bioactive compounds with unique properties. The Mediterranean seagrass Posidonia oceanica is particularly abundant in phenolics and flavonoids, which exhibit antioxidant and anti-inflammatory activities. In this study, a phenolic-rich extract (POS) was obtained from beach-cast P. oceanica leaves using supercritical fluid extraction (SFE), an eco-friendly technique that preserves thermolabile compounds and avoids organic solvents. POS was incorporated into a base cream (POS-enriched cream) to evaluate its bioactive potential in topical applications. The antioxidant capacity of POS and the cream formulation was firstly evaluated using the DPPH radical scavenging assay, confirming strong radical scavenging activity for the POS (IC₅₀ = 2.32 ± 0.33 mg/mL) and significant activity for the POS-enriched cream (IC₅₀ = 16.76 ± 0.58 mg/mL) compared to a base cream as control (IC₅₀ = 37.62 ± 1.27 mg/mL). The antioxidant and photoprotective effects of POS were investigated in human skin fibroblasts (HS-68) exposed to oxidative stress and UV-induced damage, while anti-melanogenic activity was assessed in human epidermal melanocytes (HEM) by measuring tyrosinase activity and melanin content. POS significantly reduced ROS accumulation and modulated key molecular pathways involved in apoptosis (p-JNK), inflammation (NF-κB), energy balance (p-AMPK), and collagen synthesis (Col1A1) in fibroblasts. In melanocytes, both POS pure extract and POS-enriched cream effectively inhibited tyrosinase activity while maintaining unaltered basal melanin levels, indicating a modulatory rather than fully suppressive effect. These findings highlight the potential of P. oceanica SFE extracts as sustainable natural marine-derived products for photoprotection and anti-melanogenesis, thereby bridging the gap between marine waste stream management and applications in skin health and anti-aging strategies.