New Phenolic Compounds in Posidonia oceanica Seagrass: A Comprehensive Array Using High Resolution Mass Spectrometry

Stress responses of the seagrass Cymodocea nodosa to environmentally relevant concentrations of pharmaceutical ibuprofen: Ecological implications

Pharmaceuticals like ibuprofen (IBU) entering marine environments are of great concern due to their increasing consumption and impact on wildlife. No information on IBU toxicity to seagrasses is yet available. Seagrasses form key habitats and are threatened worldwide by multiple stressors. Here, the responses of the seagrass Cymodocea nodosa to a short-term exposure (12 days) to environmentally realistic IBU concentrations (0.25-2.5-25 µg L-1), both at organism (plant growth) and sub-organism level (oxidative status, photosynthetic efficiency, and specialized metabolites production), were assessed in mesocosm. Chemical analyses to detect the presence of IBU and its metabolites in seawater and plants were also performed. IBU did not affect plant growth but caused physiological alterations which varied in severity depending on its concentration. Concentrations of 0.25 and 2.5 µg L-1 resulted in oxidative stress, but an increased antioxidant enzyme activity enabled plants to tolerate stress. A concentration of 25 µg L-1 caused greater oxidative stress, reduced antioxidant enzyme activity and specialized metabolites production, and impaired photosynthetic machinery functioning (particularly PSII). IBU was detected in seawater but not in plants suggesting no bioaccumulation. These findings indicate that C. nodosa could not withstand high IBU stress, and this could reduce its resilience to additional environmental stressors.

Biodiversity differentially impacts disease dynamics across marine and terrestrial habitats

The relationship between biodiversity and infectious disease, where increased biodiversity leads to decreased disease risk, originated from research in terrestrial disease systems and remains relatively underexplored in marine systems. Understanding the impacts of biodiversity on disease in marine versus terrestrial systems is key to continued marine ecosystem functioning, sustainable aquaculture, and restoration projects. We compare the biodiversity-disease relationship across terrestrial and marine systems, considering biodiversity at six levels: intraspecific host diversity, host microbiomes, interspecific host diversity, biotic vectors and reservoirs, parasite consumers, and parasites. We highlight gaps in knowledge regarding how these six levels of biodiversity impact diseases in marine systems and propose two model systems, the Perkinsus-oyster and Labyrinthula-seagrass systems, to address these gaps.

Influence of sprouting on the bioaccessibility and bioactivity of benzoxazinoids, phenolic acids, and flavonoids of soft and hard wheat cultivars

Grain germination increases the contents of benzoxazinoids and the antioxidant capacity of wheat and differentially affects the phytochemical composition of hard and soft wheat cultivars. It was investigated whether wheat cultivars (sprouted or not) with distinct grain texture characteristics (BRS Guaraim, soft vs. BRS Marcante, hard texture) would have different behavior in relation to changes in phytochemical compounds, bioaccessibility and antioxidant capacity during simulated gastrointestinal digestion of a tabbouleh preparation. Sprouting increased the nominal amount of phytochemicals in tabbouleh resulting in increased release of phenolic acids (up to 7.5-fold) and benzoxazinoids (up to 12.5-fold) during all digestion phases besides higher bioaccessibility (up to 2.8-fold). Sprouting caused greater increase in the bioaccessibility of phenolic acids for the soft wheat cultivar (4.5-fold) than for the hard cultivar (1.9-fold) and it increased the colon available index of phenolic acids only for the soft cultivar (1.8-fold). Flavonoids, mainly represented by apigenin glycosides, were marginally increased after sprouting but underwent relative increase along digestion being the major phytochemicals found in the bioaccessible fraction obtained after intestinal digestion (73-94% of total phytochemicals). The increase in apigenin glycosides was associated to the increase of in vitro and intracellular antioxidant capacity of tabbouleh along digestion. Sprouting increased the peroxyl radical removal capacity of tabbouleh in the gastric phase and in the non-bioaccessible fraction regardless of the cultivar. The highest hydroxyl radical removal capacities were found in non-sprouted cultivars, especially in the soft texture cultivar in the undigested and bioaccessible fractions. The bioaccessible fraction obtained after wheat digestion was more efficient to scavenge intracellular ROS than undigested samples, the highest scavenging potency being observed for the hard texture cultivar with no effect of sprouting. These findings confirm the hypothesis that the phytochemicals of hard and soft wheat cultivars (sprouted or not) have different behavior during digestion in terms of biotransformation, bioaccessibility and ability to remove reactive species and indicate that tabbouleh produced from sprouted wheat results in increased release of bioactive phytochemicals during digestion.

In Vitro Cytotoxic Effect of Aqueous Extracts from Leaves and Rhizomes of the Seagrass Posidonia oceanica (L.) Delile on HepG2 Liver Cancer Cells: Focus on Autophagy and Apoptosis

Aqueous extracts from Posidonia oceanica's green and brown (beached) leaves and rhizomes were prepared, submitted to phenolic compound and proteomic analysis, and examined for their potential cytotoxic effect on HepG2 liver cancer cells in culture. The chosen endpoints related to survival and death were cell viability and locomotory behavior, cell-cycle analysis, apoptosis and autophagy, mitochondrial membrane polarization, and cell redox state. Here, we show that 24 h exposure to both green-leaf- and rhizome-derived extracts decreased tumor cell number in a dose-response manner, with a mean half maximal inhibitory concentration (IC₅₀) estimated at 83 and 11.5 μg of dry extract/mL, respectively. Exposure to the IC₅₀ of the extracts appeared to inhibit cell motility and long-term cell replicating capacity, with a more pronounced effect exerted by the rhizome-derived preparation. The underlying death-promoting mechanisms identified involved the down-regulation of autophagy, the onset of apoptosis, the decrease in the generation of reactive oxygen species, and the dissipation of mitochondrial transmembrane potential, although, at the molecular level, the two extracts appeared to elicit partially differentiating effects, conceivably due to their diverse composition. In conclusion, P. oceanica extracts merit further investigation to develop novel promising prevention and/or treatment agents, as well as beneficial supplements for the formulation of functional foods and food-packaging material with antioxidant and anticancer properties.

Grain Germination Changes the Profile of Phenolic Compounds and Benzoxazinoids in Wheat: A Study on Hard and Soft Cultivars

Pre-harvest sprouting is a frequent problem for wheat culture that can be simulated by laboratory-based germination. Despite reducing baking properties, wheat sprouting has been shown to increase the bioavailability of some nutrients. It was investigated whether wheat cultivars bearing distinct grain texture characteristics (BRS Guaraim, soft vs. BRS Marcante, hard texture) would have different behavior in terms of the changes in phytochemical compounds during germination. Using LC-Q-TOF-MS, higher contents of benzoxazinoids and flavonoids were found in the hard cultivar than in the soft one. Free phytochemicals, mainly benzoxazinoids, increased during germination in both cultivars. Before germination, soft and hard cultivars had a similar profile of matrix-bound phytochemicals, but during germination, these compounds have been shown to decrease only in the hard-texture cultivar, due to decreased levels of phenolic acids (trans-ferulic acid) and flavonoids (apigenin) that were bound to the cell wall through ester-type bonds. These findings confirm the hypothesis that hard and soft wheat cultivars have distinct behavior during germination concerning the changes in phytochemical compounds, namely the matrix-bound compounds. In addition, germination has been shown to remarkably increase the content of benzoxazinoids and the antioxidant capacity, which could bring a health-beneficial appeal for pre-harvested sprouted grains.

Current advances on the therapeutic potential of pinocembrin: An updated review

Pinocembrin (5,7-dihydroxyflavone) is a major flavonoid found in many plants, fungi and hive products, mainly honey and propolis. Several in vitro and preclinical studies revealed numerous pharmacological activities of pinocembrin including antioxidant, anti-inflammatory, antimicrobial, neuroprotective, cardioprotective and anticancer activities. Here, we comprehensively review and critically analyze the studies carried out on pinocembrin. We also discuss its potential mechanisms of action, bioavailability, toxicity, and clinical investigations. The wide therapeutic window of pinocembrin makes it a promising drug candidate for many clinical applications. We recommend some future perspectives to improve its pharmacokinetic and pharmacodynamic properties for better delivery that may also lead to new therapeutic advances.

Low-cost Posidonia oceanica bio-adsorbent for efficient removal of antibiotic oxytetracycline from water

The presence of antibiotics as micro-contaminants in the water and aqueous environments is a health concern to humans and the ecosystem. Therefore, their elimination by adsorption to available and cheap materials in water treatment plants is a research topic of high relevance. The present paper reports on the adsorption behavior of oxytetracycline on a bio-adsorbent prepared from Posidonia oceanica; an abundant Mediterranean biomass. Characterization of the pretreated Posidonia biomaterial was achieved using several analyses such as Boehm acid-base titration method, pH_PZC determination, and analysis techniques (FTIR, ¹³C CP-MAS NMR, optical microscopy, and TGA). The pH_PZC occurred around pH 2.11. Posidonia biomaterial showed a fast and high uptake rate throughout the adsorption process, which is a definite advantage for analytical applications such as water decontamination. The experimental kinetic data fitted very rightly the pseudo-second-order kinetic model and the equilibrium uptake can adopt the bi-Langmuir isotherm model for all studied pH values which assumes adsorptions at the two localized sites. Maximum adsorption capacities of 11.8 mg∙g^-1 and 4.4 mg∙g^-1 for the two adsorption sites are reached at pH 6. The oxytetracycline adsorption process onto Posidonia bio-adsorbent is spontaneous (Δ_adsG⁰ < 0), exothermic (Δ_adsH⁰ < 0), and entropically favorable (Δ_adsS⁰ > 0). The effect of pH on adsorption behavior and the thermodynamic parameters of adsorption are consistent with a possible origin of adsorption of oxytetracycline by means of hydrogen bonding interactions between surface hydroxyl and phenolic groups of the biomaterial and oxytetracycline. The proposed green and environmentally friendly biomaterial offers potential benefits as a bio-adsorbent in the remediation of aquatic environments contaminated by various organic materials.

Specialized compounds across ontogeny in the seagrass Posidonia oceanica

Differences in phenolic composition across different ontogenic stages can be crucial in determining the interaction outcomes between plants and their surrounding biotic environment. In seagrasses, specific phenolic compounds have rarely been analyzed and remain unexplored in ontogenic stages other than non-reproductive adults. Furthermore, it is generally accepted that plants would prioritize defense (e.g., through increased phenolic content) on tissues or stages that are critical for plant fitness but how this affects nutritional quality or plant resources has been scarcely explored. We analyzed how phenolic composition, N and C content and carbohydrate resources varied among different life stages (i.e. old and young leaves of reproductive and non-reproductive plants, and leaves of seedlings) in the seagrass Posidonia oceanica. We identified five phenolic compounds, whose structures were established as hydroxycinnamate esters of tartaric acid. Also, our results show that in all examined ontogenic stages phenolic compounds have the same qualitative composition but inflorescences exhibit higher contents than vegetative tissues. We did not find a reduction in stored resources in reproductive plants, pointing to some kind of compensatory mechanism in the production or storage of resources. In contrast, seedlings seemed to have less phenolic compounds than reproductive plants, perhaps due to limited resources available to allocate to phenolic production. Our results demonstrate how different ontogenic stages change their investment in specialized phenolic compounds prioritizing different functions according to the needs and limitations of that stage.

Antioxidant Bioactivity of Extracts from Beach Cast Leaves of Posidonia oceanica (L.) Delile

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.