Marine Drugs

Fish scales are a calcium-rich biogenic waste source for hydroxyapatite (HAp), but the influence of processing route on material characteristics and calcium-release behaviour remains insufficiently understood. This study compared fish-scale-derived HAp produced by calcination and wet-chemical processing. Pretreated fish scales were processed by calcination at 1200 °C (cnHAp) or acid-assisted ultrasonic extraction followed by alkaline precipitation (wnHAp). The materials were characterised using Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy–energy-dispersive X-ray spectroscopy and high-resolution transmission electron microscopy. Calcium concentrations were measured by inductively coupled plasma optical emission spectrometry at 0, 24 and 72 h and analysed using two-way mixed-design repeated-measures analysis of variance. Both materials exhibited characteristic HAp functional groups and diffraction features but differed in crystallographic ordering and morphology. cnHAp showed greater crystallographic ordering and a smaller mean particle size (42.41 ± 12.45 nm) than wnHAp (181.09 ± 48.58 nm), with Ca/P atomic ratios of 1.87 and 1.57, respectively. Calcium concentration differed significantly by processing group, time and their interaction (all p < 0.001), with cnHAp consistently showing higher concentrations. Processing route substantially influenced the physicochemical characteristics and temporal calcium-release behaviour of fish-scale-derived HAp.

Seaweed Palmaria palmata has gained attention recently as a potential feed ingredient for livestock due to its high nitrogen content and higher digestibility. However, P. palmata has a high fiber content, which can be difficult to digest by monogastric animals. The aim of this experiment was to determine the optimal dose of xylanase for maximum release of potential prebiotics (xylooligosaccharides (XOS)) from the fiber matrix of P. palmata. Five xylanase dosages were tested: no xylanase (NX), the manufacturer-recommended dosage (1X), and two times (2X), three times (3X), or four times (4X) the manufacturer-recommended dosage in a simulated in vitro digestion experiment. Samples were analyzed for fiber as non-starch polysaccharides (NSP), and the oligosaccharide profiles were determined by high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD). P. palmata contained high levels of total NSP (44.0%), primarily as soluble xylan, while wheat bran contained mainly insoluble arabinoxylan. Increasing xylanase dose beyond 1X increased XOS release, with the highest concentration observed at 3X (p < 0.001). In conclusion, xylanase improved degradation and promoted generation of potentially prebiotic XOS from P. palmata, highlighting its potential as a functional ingredient in pig diets.

Beach-cast Posidonia oceanica represents an abundant Mediterranean marine biomass that is commonly perceived as coastal waste, despite its potential value within circular bioeconomy strategies. This study investigated the antioxidant and anti-inflammatory potential of a hydroethanolic extract obtained from beach-cast P. oceanica biomass (POE). The extract was chemically profiled by UHPLC-ESI-MS/MS and evaluated through spectrophotometric antioxidant assays, including total phenolic content, total flavonoid content, reducing power, ABTS and DPPH radical-scavenging assays. Its ability to protect plasmid DNA from oxidative damage was also assessed. Anti-inflammatory activity was investigated in LPS-stimulated RAW 264.7 macrophages by evaluating cell viability, intracellular ROS production, NO release, iNOS and COX-2 expression, NF-κB p65 nuclear translocation and MAPK phosphorylation. POE showed measurable phenolic and flavonoid contents, moderate antioxidant capacity and protection against H₂O₂/Fe²⁺-induced plasmid DNA damage. UHPLC-ESI-MS/MS analysis revealed a complex metabolite profile, with 156 annotated compounds distributed across 20 chemical classes. In macrophages, POE was not cytotoxic at 50 and 100 µg/mL and significantly reduced LPS-induced ROS and NO production. These effects were accompanied by decreased iNOS and COX-2 expression, inhibition of NF-κB p65 nuclear translocation and reduced phosphorylation of p38, ERK and JNK. In addition, POE showed no detectable cytotoxicity in NIH3T3 fibroblasts up to 10 mg/mL and no mutagenic activity in the Ames MPF™ assay using TA98 and TA100 strains, either in the absence or presence of metabolic activation. Overall, this exploratory study suggests that beach-cast P. oceanica retains bioactive properties, although further studies incorporating standardized collection protocols and quantitative chemical characterization will help clarify its potential for sustainable valorisation.