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Il presente lavoro riporta una selezione di alcuni risultati ottenuti impiegando sistemi modello rappresentati da colture cellulari di pesce, invertebrati e vertebrati marini, adottando biomarcatori finora poco indagati in organismi di questi ambienti, allo scopo di individuare sensori dello stato metabolico, la cui variazione, a lungo termine, è noto che porti a drammatiche variazioni dell’omeostasi, del ciclo cellulare e conseguenti alterazioni. Per semplificare la valutazione comparativa tra le risposte ottenute nei vari sistemi modello, riportiamo gli effetti determinati da una classe di contaminanti su cui si è concentrato, negli ultimi anni, l’interesse della ricerca in ambito ecotossicologico e ambientale, i poli-bromo-difenil-eteri (PBDE).

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.

In this study, the carotenoid astaxanthin was obtained by supercritical fluid extraction (SFE) from shrimp by-products (SBP). Its bioactive properties were evaluated in vitro in human normal and cancerous cells lines. The antioxidant activity of the extracted astaxanthin of the SFE fraction (ASTA) was tested in fibroblast cells (HS-68), by inducing oxidative stress and by evaluating the protective effect of the pre-treatment with different levels of ASTA against toxicity. The anti-proliferative activity was evaluated in hepatoma cells (HEP-G2), treated with increased concentrations of ASTA and measuring the effects on vitality and on some biomolecular markers related to oxidative stress, cell cycle, and apoptosis. It was found that pre-treating normal fibroblast cells with ASTA resulted in a marked increase in cell viability in a dose-dependent manner (P < 0.05) attesting its antioxidant power; in cancer cell line, increased concentrations of ASTA caused a time-dose-dependent decrease in the vitality, attesting its anti-proliferative activity (P < 0.05). The increased levels of the protein p-53 and the reduced levels of the proteins c-Jun and c-Fos at higher concentrations of ASTA, as well as, suggest the pro-apoptotic and anti-cancerous effects that this extract has on hepatocellular carcinomas, confirmed also by caspase-3 activation. These findings suggest biotechnological utilisation of marine by-products for nutraceutical and pharmaceutical applications avoiding the employment of organic solvents for extraction.

In the present study, the immune-stimulatory effect of two levels of honey bee pollen (5 and 10%, P5 and P10 treatment, respectively) and its supercritical fluid extract (0. 5 and 1%, E0.5 and E1, respectively) included in the diet, was tested in gilthead seabream (Sparus aurata). The in vivo trial was preceded by the evaluation of antioxidant properties of three different bee pollen extracts obtained by water, ethanol 80%, and Supercritic Fluids Extraction (SFE). The preliminary evaluation attested that the SFE showed the lowest extraction yield (10.47%) compared to ethanol 80% (48.61%) and water (45.99%). SFE extract showed good antioxidant properties with high polyphenol content (13.06 mg GAE/g), radical scavenging activity (3.12 mg/ml), reducing power (38.68 mg/mL EC50). On the contrary, the water extract showed the significantly lowest polyphenol content (2 mg GAE/g; P < 0.05). The results of in vivo trial demonstrate that the diets supplemented with SFE bee pollen extract had a stimulatory effect on fish serum immunity, respect to the inclusion of raw pollen, this latter revealing some inhibitory effects in the immune response, such a decrease of serum peroxidase and lysozyme activities, particularly in P10 group significantly different (P < 0.05) from the control group. On the contrary, serum peroxidase, protease, antiprotease, were significantly increased in fish fed the diets supplemented with supercritical fluid extract, respect to the fish fed on control and on diets supplemented with 5 and 10% of raw pollen. For what concerns the bactericidal activity against Vibrio harveyii, all the treatments containing bee pollen regardless of the type showed their serum bactericidal activity significantly increased with respect to the control groups (p < 0.05). Given its high antioxidant properties, the absence of toxic solvents and the positive action carried out on improving the humoral response in gilthead seam bream, honey bee pollen SFE extract can be taken into account in the formulation of fish feeds.

This study aimed at the characterization of the antioxidant power of polyphenol extracts (PE) obtained from the algae Cystoseira foeniculacea (CYS) (Phaeophyta) and from the halophyte Halocnemum strobilaceum (HAL), growing in the solar saltworks of western Sicily (Italy), and at the evaluation of their anti-microfouling properties, in order to correlate these activities to defense strategies in extreme environmental conditions. The antioxidant properties were assessed in the PE based on the total antioxidant activity test and the reducing power test, the anti-microfouling properties of the two PE were evaluated by measuring the growth inhibition of marine fish and shellfish pathogen bacteria as well as marine surface fouling bacteria and microalgae exposed to the fractions. Similar polyphenol content (CYS 5.88 &plusmn, 0.75 and HAL 6.03 &plusmn, 0.25 mg gallic acid equivalents (GAE) g&minus, 1 dried weight, DW) and similar reducing power percentage (93.91 &plusmn, 4.34 and 90.03 &plusmn, 6.19) were recorded for both species, even if they exhibited a different total antioxidant power (measured by the percentage of inhibition of the radical 2,2 diphenyl-1-picrylhydrazyl DPPH), with CYS (79.30) more active than HAL (59.90). Both PE showed anti-microfouling properties, being inhibitors of adhesion and growth of marine fish and shellfish pathogen bacteria (V. aestuarianus, V. carchariae, V. harveyi, P. elyakovii, H. aquamarina) and fouling bacteria (V. natriegens, V. proteolyticus, P. iirgensii, R. litoralis) with minimum inhibitory concentrations comparable to the commercial antifouling products used as a positive control (SEA-NINE&trade, 211N). Only CYS was a significant inhibitor of the microalgae strains tested, being able to reduce E. gayraliae and C. closterium growth (MIC 10 &micro, g&middot, mL&minus, 1) and the adhesion of all three strains tested (E. gayraliae, C. closterium and P. purpureum), suggesting its promise for use as an antifouling (AF) product.