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Mar. Drugs, Volume 16, Issue 7 (July 2018)

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Cover Story (view full-size image) Pufferfish saxitoxin and tetrodotoxin (TTX) binding protein (PSTBP) is a glycoprotein that we [...] Read more.
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Open AccessReview Review of Chromatographic Bioanalytical Assays for the Quantitative Determination of Marine-Derived Drugs for Cancer Treatment
Mar. Drugs 2018, 16(7), 246; https://doi.org/10.3390/md16070246
Received: 15 June 2018 / Revised: 15 June 2018 / Accepted: 18 July 2018 / Published: 23 July 2018
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Abstract
The discovery of marine-derived compounds for the treatment of cancer has seen a vast increase over the last few decades. Bioanalytical assays are pivotal for the quantification of drug levels in various matrices to construct pharmacokinetic profiles and to link drug concentrations to
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The discovery of marine-derived compounds for the treatment of cancer has seen a vast increase over the last few decades. Bioanalytical assays are pivotal for the quantification of drug levels in various matrices to construct pharmacokinetic profiles and to link drug concentrations to clinical outcomes. This review outlines the different analytical methods that have been described for marine-derived drugs in cancer treatment hitherto. It focuses on the major parts of the bioanalytical technology, including sample type, sample pre-treatment, separation, detection, and quantification. Full article
(This article belongs to the collection Marine Compounds and Cancer) Printed Edition available
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Open AccessArticle Sorbicillasins A–B and Scirpyrone K from a Deep-Sea-Derived Fungus, Phialocephala sp. FL30r
Mar. Drugs 2018, 16(7), 245; https://doi.org/10.3390/md16070245
Received: 6 June 2018 / Revised: 18 July 2018 / Accepted: 18 July 2018 / Published: 23 July 2018
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Abstract
Two new nitrogen-containing sorbicillinoids named sorbicillasins A and B (1 and 2) and a new 3,4,6-trisubstituted α-pyrone derivative, scirpyrone K (3), together with two known biosynthetically related polyketides (45), were isolated from the deep-sea-derived
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Two new nitrogen-containing sorbicillinoids named sorbicillasins A and B (1 and 2) and a new 3,4,6-trisubstituted α-pyrone derivative, scirpyrone K (3), together with two known biosynthetically related polyketides (45), were isolated from the deep-sea-derived fungus Phialocephala sp. FL30r by using the OSMAC (one strain-many compounds) method. The structures of 13, including absolute configurations, were deduced based on MS, NMR, and time-dependent density functional theory (TD-DFT) calculations of specific ECD (electronic circular dichroism) spectra. Compounds 1 and 2 possessed a novel hexahydropyrimido[2,1-a] isoindole moiety, and compound 3 exhibited weak radical scavenging activity against DPPH (2,2-diphenyl-1-picrylhydrazyl) with an IC50 value of 27.9 μM. Full article
(This article belongs to the Special Issue Natural Products from Marine Fungi)
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Open AccessReview Extending the “One Strain Many Compounds” (OSMAC) Principle to Marine Microorganisms
Mar. Drugs 2018, 16(7), 244; https://doi.org/10.3390/md16070244
Received: 5 July 2018 / Revised: 17 July 2018 / Accepted: 19 July 2018 / Published: 23 July 2018
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Abstract
Genomic data often highlights an inconsistency between the number of gene clusters identified using bioinformatic approaches as potentially producing secondary metabolites and the actual number of chemically characterized secondary metabolites produced by any given microorganism. Such gene clusters are generally considered as “silent”,
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Genomic data often highlights an inconsistency between the number of gene clusters identified using bioinformatic approaches as potentially producing secondary metabolites and the actual number of chemically characterized secondary metabolites produced by any given microorganism. Such gene clusters are generally considered as “silent”, meaning that they are not expressed under laboratory conditions. Triggering expression of these “silent” clusters could result in unlocking the chemical diversity they control, allowing the discovery of novel molecules of both medical and biotechnological interest. Therefore, both genetic and cultivation-based techniques have been developed aimed at stimulating expression of these “silent” genes. The principles behind the cultivation based approaches have been conceptualized in the “one strain many compounds” (OSMAC) framework, which underlines how a single strain can produce different molecules when grown under different environmental conditions. Parameters such as, nutrient content, temperature, and rate of aeration can be easily changed, altering the global physiology of a microbial strain and in turn significantly affecting its secondary metabolism. As a direct extension of such approaches, co-cultivation strategies and the addition of chemical elicitors have also been used as cues to activate “silent” clusters. In this review, we aim to provide a focused and comprehensive overview of these strategies as they pertain to marine microbes. Moreover, we underline how changes in some parameters which have provided important results in terrestrial microbes, but which have rarely been considered in marine microorganisms, may represent additional strategies to awaken “silent” gene clusters in marine microbes. Unfortunately, the empirical nature of the OSMAC approach forces scientists to perform extensive laboratory experiments. Nevertheless, we believe that some computation and experimental based techniques which are used in other disciplines, and which we discuss; could be effectively employed to help streamline the OSMAC based approaches. We believe that natural products discovery in marine microorganisms would be greatly aided through the integration of basic microbiological approaches, computational methods, and technological innovations, thereby helping unearth much of the as yet untapped potential of these microorganisms. Full article
(This article belongs to the Special Issue Marine Bacteria as Sources of Bioactive Compounds)
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Open AccessArticle Structural Characteristics and Anticoagulant Property In Vitro and In Vivo of a Seaweed Sulfated Rhamnan
Mar. Drugs 2018, 16(7), 243; https://doi.org/10.3390/md16070243
Received: 6 June 2018 / Revised: 2 July 2018 / Accepted: 18 July 2018 / Published: 20 July 2018
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Abstract
Great diversity and metabolite complexity of seaweeds offer a unique and exclusive source of renewable drug molecules. Polysaccharide from seaweed has potential as a promising candidate for marine drug development. In the present study, seaweed polysaccharide (SPm) was isolated from Monostroma angicava,
[...] Read more.
Great diversity and metabolite complexity of seaweeds offer a unique and exclusive source of renewable drug molecules. Polysaccharide from seaweed has potential as a promising candidate for marine drug development. In the present study, seaweed polysaccharide (SPm) was isolated from Monostroma angicava, the polymeric repeat units and anticoagulant property in vitro and in vivo of SPm were investigated. SPm was a sulfated polysaccharide which was mainly constituted by 3-linked, 2-linked-α-l-rhamnose residues with partially sulfate groups at C-2 of 3-linked α-l-rhamnose residues and C-3 of 2-linked α-l-rhamnose residues. Small amounts of xylose and glucuronic acid exist in the forms of β-d-Xylp(4SO4)-(1→ and β-d-GlcA-(1→. SPm effectively prolonged clotting time as evaluated by the activated partial thromboplastin time and thrombin time assays, and exhibited strong anticoagulant activity in vitro and in vivo. The fibrin(ogen)olytic and thrombolytic properties of SPm were evaluated by plasminogen activator inhibitior-1, fibrin degradation products, D-dimer and clot lytic rate assays using rats plasma, and the results showed that SPm possessed high fibrin(ogen)olytic and thrombolytic properties. These results suggested that SPm has potential as a novel anticoagulant agent. Full article
(This article belongs to the Special Issue Seaweeds and Their Biological Actions)
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Open AccessArticle Zoanthamine Alkaloids from the Zoantharian Zoanthus cf. pulchellus and Their Effects in Neuroinflammation
Mar. Drugs 2018, 16(7), 242; https://doi.org/10.3390/md16070242
Received: 1 July 2018 / Revised: 15 July 2018 / Accepted: 19 July 2018 / Published: 20 July 2018
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Abstract
Two new zoanthamine alkaloids, namely 3-acetoxynorzoanthamine (1) and 3-acetoxyzoanthamine (2), have been isolated from the zoantharian Zoanthus cf. pulchellus collected off the coast of the Santa Elena Peninsula, Ecuador, together with three known derivatives: zoanthamine, norzoanthamine, and 3-hydroxynorzoanthamine. The
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Two new zoanthamine alkaloids, namely 3-acetoxynorzoanthamine (1) and 3-acetoxyzoanthamine (2), have been isolated from the zoantharian Zoanthus cf. pulchellus collected off the coast of the Santa Elena Peninsula, Ecuador, together with three known derivatives: zoanthamine, norzoanthamine, and 3-hydroxynorzoanthamine. The chemical structures of 1 and 2 were determined by interpretation of their 1D and 2D NMR data and comparison with literature data. This is the first report of zoanthamine-type alkaloids from Zoanthus cf. pulchellus collected in the Tropical Eastern Pacific. The neuroinflammatory activity of all the isolated compounds was evaluated in microglia BV-2 cells and high inhibitory effects were observed in reactive oxygen species (ROS) and nitric oxide (NO) generation. Full article
(This article belongs to the Special Issue Marine Anti-inflammatory Agents)
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Open AccessArticle Preclinical Evaluation of Discorhabdins in Antiangiogenic and Antitumor Models
Mar. Drugs 2018, 16(7), 241; https://doi.org/10.3390/md16070241
Received: 20 June 2018 / Revised: 9 July 2018 / Accepted: 16 July 2018 / Published: 19 July 2018
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Abstract
Elements of the hypoxia inducible factor (HIF) transcriptional system, a key regulator of the cellular hypoxic response, are up-regulated in a range of cancer cells. HIF is fundamentally involved in tumor angiogenesis, invasion, and energy metabolism. Inhibition of the transcriptional activity of HIF
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Elements of the hypoxia inducible factor (HIF) transcriptional system, a key regulator of the cellular hypoxic response, are up-regulated in a range of cancer cells. HIF is fundamentally involved in tumor angiogenesis, invasion, and energy metabolism. Inhibition of the transcriptional activity of HIF may be of therapeutic benefit to cancer patients. We recently described the identification of two marine pyrroloiminoquinone alkaloids with potent activity in inhibiting the interaction between the oncogenic transcription factor HIF-1α and the coactivator protein p300. Herein, we present further characterization data for these two screening hits: discorhabdin H (1) and discorhabdin L (2), with a specific focus on their anti-angiogenic and anti-tumor effects. We demonstrated that only discorhabdin L (2) possesses excellent anti-angiogenic activity in inhibiting endothelial cell proliferation and tube formation, as well as decreasing microvessel outgrowth in the ex vivo rat aortic ring assay. We further showed that discorhabdin L (2) significantly inhibits in vivo prostate tumor growth in a LNCaP xenograft model. In conclusion, our findings suggest that discorhabdin L (2) represents a promising HIF-1α inhibitor worthy of further drug development. Full article
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Open AccessCommunication (−)-Homosalinosporamide A and Its Mode of Proteasome Inhibition: An X-ray Crystallographic Study
Mar. Drugs 2018, 16(7), 240; https://doi.org/10.3390/md16070240
Received: 15 June 2018 / Revised: 5 July 2018 / Accepted: 11 July 2018 / Published: 19 July 2018
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Abstract
Upon acylation of the proteasome by the β-lactone inhibitor salinosporamide A (SalA), tetrahydrofuran formation occurs by intramolecular alkylation of the incipient alkoxide onto the choroethyl sidechain and irreversibly blocks the active site. Our previously described synthetic approach to SalA, utilizing a bioinspired, late-stage,
[...] Read more.
Upon acylation of the proteasome by the β-lactone inhibitor salinosporamide A (SalA), tetrahydrofuran formation occurs by intramolecular alkylation of the incipient alkoxide onto the choroethyl sidechain and irreversibly blocks the active site. Our previously described synthetic approach to SalA, utilizing a bioinspired, late-stage, aldol-β-lactonization strategy to construct the bicyclic β-lactone core, enabled synthesis of (–)-homosalinosporamide A (homoSalA). This homolog was targeted to determine whether an intramolecular tetrahydropyran is formed in a similar manner to SalA. Herein, we report the X-ray structure of the yeast 20S proteasome:homoSalA-complex which reveals that tetrahydropyran ring formation does not occur despite comparable potency at the chymotrypsin-like active site in a luminogenic enzyme assay. Thus, the natural product derivative homoSalA blocks the proteasome by a covalent reversible mode of action, opening the door for further fine-tuning of proteasome inhibition. Full article
(This article belongs to the Special Issue Marine Drugs Interact with Functional Proteins)
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Open AccessArticle Protective Effect of Sulfated Polysaccharides from Celluclast-Assisted Extract of Hizikia fusiforme Against Ultraviolet B-Induced Skin Damage by Regulating NF-κB, AP-1, and MAPKs Signaling Pathways In Vitro in Human Dermal Fibroblasts
Mar. Drugs 2018, 16(7), 239; https://doi.org/10.3390/md16070239
Received: 12 June 2018 / Revised: 3 July 2018 / Accepted: 14 July 2018 / Published: 17 July 2018
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Abstract
Our previous study evaluated the antioxidant activities of sulfated polysaccharides from Celluclast-assisted extract of Hizikia fusiforme (HFPS) in vitro in Vero cells and in vivo in zebrafish. The results showed that HFPS possesses strong antioxidant activity and suggested the potential photo-protective activities of
[...] Read more.
Our previous study evaluated the antioxidant activities of sulfated polysaccharides from Celluclast-assisted extract of Hizikia fusiforme (HFPS) in vitro in Vero cells and in vivo in zebrafish. The results showed that HFPS possesses strong antioxidant activity and suggested the potential photo-protective activities of HFPS. Hence, in the present study, we investigated the protective effects of HFPS against ultraviolet (UV) B-induced skin damage in vitro in human dermal fibroblasts (HDF cells). The results indicate that HFPS significantly reduced intracellular reactive oxygen species (ROS) level and improved the viability of UVB-irradiated HDF cells in a dose-dependent manner. Furthermore, HFPS significantly inhibited intracellular collagenase and elastase activities, remarkably protected collagen synthesis, and reduced matrix metalloproteinases (MMPs) expression by regulating nuclear factor kappa B (NF-κB), activator protein 1 (AP-1), and mitogen-activated protein kinases (MAPKs) signaling pathways in UVB-irradiated HDF cells. These results suggest that HFPS possesses strong UV protective effect, and can be a potential ingredient in the pharmaceutical and cosmetic industries. Full article
(This article belongs to the Special Issue Anti-Photoagaing and Photo-Protective Compounds from Marine Organisms)
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Open AccessArticle A Sterol from Soft Coral Induces Apoptosis and Autophagy in MCF-7 Breast Cancer Cells
Mar. Drugs 2018, 16(7), 238; https://doi.org/10.3390/md16070238
Received: 20 March 2018 / Revised: 9 July 2018 / Accepted: 11 July 2018 / Published: 17 July 2018
Cited by 1 | Viewed by 687 | PDF Full-text (3192 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The peroxisome proliferator-activated receptor γ (PPARγ) is a nuclear receptor that plays a key role in regulating cellular metabolism, and is a therapeutic target for cancer therapy. To search for potential PPARγ activators, a compound library comprising 11 marine compounds was examined. Among
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The peroxisome proliferator-activated receptor γ (PPARγ) is a nuclear receptor that plays a key role in regulating cellular metabolism, and is a therapeutic target for cancer therapy. To search for potential PPARγ activators, a compound library comprising 11 marine compounds was examined. Among them, a sterol, 3β,11-dihydroxy-9,11-secogorgost-5-en-9-one (compound 1), showed the highest PPARγ activity with an IC50 value of 8.3 μM for inhibiting human breast adenocarcinoma cell (MCF-7) growth. Western blotting experiments showed that compound 1 induces caspase activation and PARP cleavage. In addition, compound 1 modulated the expression of various PPARγ-regulated downstream biomarkers including cyclin D1, cyclin-dependent kinase (CDK)6, B-cell lymphoma 2 (Bcl-2), p38, and extracellular-signal-regulated kinase (ERK). Moreover, compound 1 increased reactive oxygen species (ROS) generation, upregulated the phosphorylation and expression of H2AX, and induced autophagy. Interestingly, pre-treatment with the autophagy inhibitor 3-methyladenine rescued cells from compound 1-induced growth inhibition, which indicates that the cytotoxic effect of compound 1 is, in part, attributable to its ability to induce autophagy. In conclusion, these findings suggest the translational potential of compound 1 in breast cancer therapy. Full article
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Open AccessReview Overview on the Antihypertensive and Anti-Obesity Effects of Secondary Metabolites from Seaweeds
Mar. Drugs 2018, 16(7), 237; https://doi.org/10.3390/md16070237
Received: 11 June 2018 / Revised: 20 June 2018 / Accepted: 12 July 2018 / Published: 14 July 2018
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Abstract
Hypertension and obesity are two significant factors that contribute to the onset and exacerbation of a cascade of mechanisms including activation of the sympathetic and renin-angiotensin systems, oxidative stress, release of inflammatory mediators, increase of adipogenesis and thus promotion of systemic dysfunction that
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Hypertension and obesity are two significant factors that contribute to the onset and exacerbation of a cascade of mechanisms including activation of the sympathetic and renin-angiotensin systems, oxidative stress, release of inflammatory mediators, increase of adipogenesis and thus promotion of systemic dysfunction that leads to clinical manifestations of cardiovascular diseases. Seaweeds, in addition to their use as food, are now unanimously acknowledged as an invaluable source of new natural products that may hold noteworthy leads for future drug discovery and development, including in the prevention and/or treatment of the cardiovascular risk factors. Several compounds including peptides, phlorotannins, polysaccharides, carotenoids, and sterols, isolated from brown, red and green macroalgae exhibit significant anti-hypertensive and anti-obesity properties. This review will provide a comprehensive overview of the recent advances on bioactive pure compounds isolated from different seaweed sources focusing on their potential use as drugs to treat or prevent hypertension and obesity. On the other hand, although it is obvious that macroalgae represent promising sources of antihypertensive and anti-obesity compounds, it is also clear that further efforts are required to fully understand their cellular mechanisms of action, to establish structure-inhibition relationships and mainly to evaluate them in pre-clinical and clinical trials. Full article
(This article belongs to the Special Issue Discovery and Application of Macroalgae-Derived Natural Products)
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Open AccessFeature PaperReview Computational Methodologies in the Exploration of Marine Natural Product Leads
Mar. Drugs 2018, 16(7), 236; https://doi.org/10.3390/md16070236
Received: 14 June 2018 / Revised: 2 July 2018 / Accepted: 6 July 2018 / Published: 13 July 2018
Cited by 1 | Viewed by 880 | PDF Full-text (5203 KB) | HTML Full-text | XML Full-text
Abstract
Computational methodologies are assisting the exploration of marine natural products (MNPs) to make the discovery of new leads more efficient, to repurpose known MNPs, to target new metabolites on the basis of genome analysis, to reveal mechanisms of action, and to optimize leads.
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Computational methodologies are assisting the exploration of marine natural products (MNPs) to make the discovery of new leads more efficient, to repurpose known MNPs, to target new metabolites on the basis of genome analysis, to reveal mechanisms of action, and to optimize leads. In silico efforts in drug discovery of NPs have mainly focused on two tasks: dereplication and prediction of bioactivities. The exploration of new chemical spaces and the application of predicted spectral data must be included in new approaches to select species, extracts, and growth conditions with maximum probabilities of medicinal chemistry novelty. In this review, the most relevant current computational dereplication methodologies are highlighted. Structure-based (SB) and ligand-based (LB) chemoinformatics approaches have become essential tools for the virtual screening of NPs either in small datasets of isolated compounds or in large-scale databases. The most common LB techniques include Quantitative Structure–Activity Relationships (QSAR), estimation of drug likeness, prediction of adsorption, distribution, metabolism, excretion, and toxicity (ADMET) properties, similarity searching, and pharmacophore identification. Analogously, molecular dynamics, docking and binding cavity analysis have been used in SB approaches. Their significance and achievements are the main focus of this review. Full article
(This article belongs to the Special Issue Progress on Marine Natural Products as Lead Compounds)
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Open AccessArticle Green Alga Ulva spp. Hydrolysates and Their Peptide Fractions Regulate Cytokine Production in Splenic Macrophages and Lymphocytes Involving the TLR4-NFκB/MAPK Pathways
Mar. Drugs 2018, 16(7), 235; https://doi.org/10.3390/md16070235
Received: 25 May 2018 / Revised: 27 June 2018 / Accepted: 10 July 2018 / Published: 11 July 2018
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Abstract
Hydrolysates of food protein sources have immunomodulatory effects, which are of interest for use as functional foods. In this study, we have characterized the immune regulatory effect on rat splenocytes, macrophages and T lymphocytes of Ulva spp. hydrolysates and their peptide fractions with
[...] Read more.
Hydrolysates of food protein sources have immunomodulatory effects, which are of interest for use as functional foods. In this study, we have characterized the immune regulatory effect on rat splenocytes, macrophages and T lymphocytes of Ulva spp. hydrolysates and their peptide fractions with or without in vitro gastrointestinal digestion and/or ultrafiltration. IL-10 was induced in almost all conditions and cell types obtained from wild type animals. The induction was in general increased by ultrafiltration and in vitro gastrointestinal digestion. TNF was also induced in basal conditions. In turn, TNF and IFN-γ production was attenuated by the hydrolysate products in lipopolysaccharide or concanavalin A immune stimulated cells. Inhibitors for the activation of NFκB, MAPK p38 and JNK inhibited IL-10 induction in rat splenocytes. The response was dramatically attenuated in TLR4−/− cells, and only modestly in TLR2−/− cells. Food peptides from Ulva spp. genus exert anti-inflammatory effects in immune cells mediated by TLR4 and NFκB. Similarity with the immunomodulatory profile of protein hydrolysates from other sources suggests a common mechanism. Full article
(This article belongs to the Special Issue Seaweeds and Their Biological Actions)
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Open AccessReview Cardioprotective Effects of Omega-3 Polyunsaturated Fatty Acids: Dichotomy between Experimental and Clinical Studies
Mar. Drugs 2018, 16(7), 234; https://doi.org/10.3390/md16070234
Received: 10 June 2018 / Revised: 22 June 2018 / Accepted: 3 July 2018 / Published: 10 July 2018
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Abstract
The high-fat diet of North Americans has a major impact on cardiovascular disease occurrence. Notably, fatty acids have been identified as important factors that could modulate such diseases, especially myocardial infarction (MI). Experimentally, omega-3 polyunsaturated fatty acids (PUFA) have demonstrated positive effects on
[...] Read more.
The high-fat diet of North Americans has a major impact on cardiovascular disease occurrence. Notably, fatty acids have been identified as important factors that could modulate such diseases, especially myocardial infarction (MI). Experimentally, omega-3 polyunsaturated fatty acids (PUFA) have demonstrated positive effects on cardiovascular disorders and have also shown cardioprotection by decreasing MI size. Although many animal experiments have clearly established the benefits of omega-3 PUFA, clinical studies have not reached similar conclusions. In fact, the findings of recent clinical investigations indicate that omega-3 PUFA play only a minor role in cardiovascular health. This dichotomy between experimental and clinical studies may be due to different parameters that are not taken into account in animal experiments. We have recently observed that the high consumption of omega-6 PUFA results in significant attenuation of the beneficial effect of omega-3 PUFA on MI. We believe that part of the dichotomy between experimental and clinical research may be related to the quantity of omega-6 PUFA ingested. This review of the data indicates the importance of considering omega-6 PUFA consumption in omega-3 PUFA studies. Full article
(This article belongs to the Special Issue Marine Natural Products for Cardiovascular Disease)
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Open AccessFeature PaperReview Marine Carbohydrate-Based Compounds with Medicinal Properties
Mar. Drugs 2018, 16(7), 233; https://doi.org/10.3390/md16070233
Received: 5 June 2018 / Revised: 2 July 2018 / Accepted: 4 July 2018 / Published: 9 July 2018
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Abstract
The oceans harbor a great diversity of organisms, and have been recognized as an important source of new compounds with nutritional and therapeutic potential. Among these compounds, carbohydrate-based compounds are of particular interest because they exhibit numerous biological functions associated with their chemical
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The oceans harbor a great diversity of organisms, and have been recognized as an important source of new compounds with nutritional and therapeutic potential. Among these compounds, carbohydrate-based compounds are of particular interest because they exhibit numerous biological functions associated with their chemical diversity. This gives rise to new substances for the development of bioactive products. Many are the known applications of substances with glycosidic domains obtained from marine species. This review covers the structural properties and the current findings on the antioxidant, anti-inflammatory, anticoagulant, antitumor and antimicrobial activities of medium and high molecular-weight carbohydrates or glycosylated compounds extracted from various marine organisms. Full article
(This article belongs to the Special Issue Marine Glycosides)
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Open AccessArticle Asperindoles A–D and a p-Terphenyl Derivative from the Ascidian-Derived Fungus Aspergillus sp. KMM 4676
Mar. Drugs 2018, 16(7), 232; https://doi.org/10.3390/md16070232
Received: 7 June 2018 / Revised: 2 July 2018 / Accepted: 3 July 2018 / Published: 9 July 2018
Cited by 2 | Viewed by 654 | PDF Full-text (3849 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Four new indole-diterpene alkaloids asperindoles A–D (14) and the known p-terphenyl derivative 3″-hydroxyterphenyllin (5) were isolated from the marine-derived strain of the fungus Aspergillus sp., associated with an unidentified colonial ascidian. The structures of 1
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Four new indole-diterpene alkaloids asperindoles A–D (14) and the known p-terphenyl derivative 3″-hydroxyterphenyllin (5) were isolated from the marine-derived strain of the fungus Aspergillus sp., associated with an unidentified colonial ascidian. The structures of 15 were established by 2D NMR and HRESIMS data. The absolute configurations of all stereocenters of 14 were determined by the combination of ROESY data, coupling constants analysis, and biogenetic considerations. Asperindoles C and D contain a 2-hydroxyisobutyric acid (2-HIBA) residue, rarely found in natural compounds. Asperindole A exhibits cytotoxic activity against hormone therapy-resistant PC-3 and 22Rv1, as well as hormone therapy-sensitive human prostate cancer cells, and induces apoptosis in these cells at low-micromolar concentrations. Full article
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Open AccessArticle Four New C9 Metabolites from the Sponge-Associated Fungus Gliomastix sp. ZSDS1-F7-2
Mar. Drugs 2018, 16(7), 231; https://doi.org/10.3390/md16070231
Received: 26 May 2018 / Revised: 6 July 2018 / Accepted: 6 July 2018 / Published: 9 July 2018
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Abstract
Four new structurally related metabolites, one γ-lactone named gliomasolide F (1), one δ-lactone named gliomasolide G (2), and two medium-chain fatty acids named gliomacids A–B (34), each containing nine carbons in total, were identified from
[...] Read more.
Four new structurally related metabolites, one γ-lactone named gliomasolide F (1), one δ-lactone named gliomasolide G (2), and two medium-chain fatty acids named gliomacids A–B (34), each containing nine carbons in total, were identified from the sponge-associated fungus Gliomastix sp. ZSDS1-F7-2. The planar chemical structures of these novel C9 metabolites were elucidated by nuclear magnetic resonance (NMR) spectroscopic methods, in connection with the analysis of high-resolution mass spectrometry (HRMS) and infrared (IR) data. The absolute configuration of 1, was determined by comparisons of experimental circular dichroism (CD) and optical rotation (OR) value with corresponding ones computed by quantum chemistry. The relative configuration of 2 was determined by the Nuclear Overhauser effect spectroscopy (NOESY) spectrum, while its absolute configuration was tentatively determined in view of the biogenetic and biosynthetic relationships between 1 and 2. Compounds 34, originally as an inseparable mixture, were successfully isolated after chemical modifications. The stereo-chemistries of compounds 34 were assumed by comparison of 13C NMR with those of the similar moiety reported in literature, in addition to the biogenetic and biosynthetic relationships with 1. The plausible biosynthetic relationships among these four C9 metabolites were supposed. Biologically, compounds 14 showed no cytotoxic effect against HeLa cell line at concentrations up to 25 μg/mL, while 1 exhibited moderate antifouling activity against the settlement of Balanus amphitrite larvae with IC50 being 12.8 μg/mL and LC50 > 25 μg/mL. The co-occurrence of macrolides gliomasolides A—E and four C9 metabolites in the same fermentation culture made us assume that these C9 metabolites might be biosynthetic building blocks toward the construction of more complex macrolides such as gliomasolides A—E or other unidentified polyketides. Full article
(This article belongs to the Special Issue Marine Natural Products from Symbiotic Ecosystems)
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Open AccessArticle Mycophenolic Acid Derivatives with Immunosuppressive Activity from the Coral-Derived Fungus Penicillium bialowiezense
Mar. Drugs 2018, 16(7), 230; https://doi.org/10.3390/md16070230
Received: 12 June 2018 / Revised: 3 July 2018 / Accepted: 4 July 2018 / Published: 7 July 2018
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Abstract
Mycophenolic acid (MPA) is a potent inosine-5′-monophosphate dehydrogenase (IMPDH) inhibitor for immunosuppressive chemotherapy. Most importantly, as the 2-morpholinoethyl ester prodrug of MPA, mycophenolate mofetil (MMF) is a well-known immunosuppressant used to prevent rejection in organ transplantations. Nevertheless, due to its frequently occurred side
[...] Read more.
Mycophenolic acid (MPA) is a potent inosine-5′-monophosphate dehydrogenase (IMPDH) inhibitor for immunosuppressive chemotherapy. Most importantly, as the 2-morpholinoethyl ester prodrug of MPA, mycophenolate mofetil (MMF) is a well-known immunosuppressant used to prevent rejection in organ transplantations. Nevertheless, due to its frequently occurred side effects, searching for new therapeutic agents is ongoing. In our current work, by virtue of efficient bioassay-guided fractionation and purification, eleven mycophenolic acid derivatives, including five previously unreported metabolites (37) and six known compounds (1, 2, and 811), were obtained from the coral-derived fungus Penicillium bialowiezense. Their structures were elucidated by means of extensive spectroscopic analyses (including 1D and 2D NMR and HRESIMS data) and comparison of the NMR and other physical data with those reported in the literature in the case of the known compounds. All the isolates 111 were evaluated for the immunosuppressive activity, and 13 showed potent IMPDH2 inhibitory potency with IC50 values of 0.84–0.95 μM, which were comparable to that of MPA (the positive control), while 410 showed significant inhibitory potency with IC50 values of 3.27–24.68 μM. All the MPA derivatives showed promising immunosuppressive activity, endowing them as potential drug leads for organ transplantations and autoimmune related diseases. Full article
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Open AccessArticle Polyketides and Alkaloids from the Marine-Derived Fungus Dichotomomyces cejpii F31-1 and the Antiviral Activity of Scequinadoline A against Dengue Virus
Mar. Drugs 2018, 16(7), 229; https://doi.org/10.3390/md16070229
Received: 13 June 2018 / Revised: 27 June 2018 / Accepted: 3 July 2018 / Published: 6 July 2018
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Abstract
In our continuous chemical investigation on the marine-derived fungus Dichotomomyces cejpii F31-1, two new polyketides dichocetides B-C (1, 2), two new alkaloids dichotomocejs E-F (3, 4), and three known fumiquinozalines: scequinadoline A (5), quinadoline A
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In our continuous chemical investigation on the marine-derived fungus Dichotomomyces cejpii F31-1, two new polyketides dichocetides B-C (1, 2), two new alkaloids dichotomocejs E-F (3, 4), and three known fumiquinozalines: scequinadoline A (5), quinadoline A (6), and scequinadoline E (7) were discovered from the culture broth and the mycelium in the culture medium, by the addition of l-tryptophan and l-phenylalanine. Their chemical structures were established by one dimensional (1D), two dimensional (2D) nuclear magnetic resonance (NMR) and high resolution mass spectrometry (HR-MS) data. Among them, scequinadoline A (5) exhibited significant inhibitory activity against dengue virus serotype 2 production by standard plaque assay, equivalent to the positive control andrographlide. Scequinadoline A (5) possesses the potential for further development as a dengue virus inhibitor. Full article
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Open AccessArticle Processing Optimization and Characterization of Angiotensin-Ι-Converting Enzyme Inhibitory Peptides from Lizardfish (Synodus macrops) Scale Gelatin
Mar. Drugs 2018, 16(7), 228; https://doi.org/10.3390/md16070228
Received: 21 May 2018 / Revised: 25 June 2018 / Accepted: 29 June 2018 / Published: 4 July 2018
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Abstract
Hypertension can cause coronary heart disease. Synthetic angiotensin-converting enzyme (ACE) inhibitors are effective antihypertensive drugs but often cause side effects. The aim of this study was to prepare potential ACE inhibitors from scales. Gelatin was extracted from lizardfish scales. Then, scale gelatin was
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Hypertension can cause coronary heart disease. Synthetic angiotensin-converting enzyme (ACE) inhibitors are effective antihypertensive drugs but often cause side effects. The aim of this study was to prepare potential ACE inhibitors from scales. Gelatin was extracted from lizardfish scales. Then, scale gelatin was enzymolyzed to prepare ACE inhibitory peptides using response surface methodology. Proteolytic conditions after optimization were as follows: pH 7.0, enzyme substrate ratio 3.2%, temperature 47 °C, and proteolysis lasting 2 h and 50 min. The experimental ACE inhibitory activity under optimal conditions was 86.0 ± 0.4%. Among the 118 peptides identified from gelatin hydrolysates, 87.3% were hydrophilic and 93.22% had a molecular weight <2000 Da. Gelatin peptides had high stability upon exposure to high temperature and pH as well as gastrointestinal tract enzymes. Gelatin peptides showed an antihypertensive effect in spontaneously hypertensive rats at a dosage of 2 g/kg in the long-term experiments. A new ACE inhibitory peptide was isolated from gelatin hydrolysates, and was identified as AGPPGSDGQPGAK with an IC50 value of 420 ± 20 μM. In this way, ACE inhibitory peptides derived from scale gelatin have the potential to be used as healthy ACE-inhibiting drug raw materials. Full article
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Open AccessReview Harnessing Marine Biocatalytic Reservoirs for Green Chemistry Applications through Metagenomic Technologies
Mar. Drugs 2018, 16(7), 227; https://doi.org/10.3390/md16070227
Received: 23 May 2018 / Revised: 13 June 2018 / Accepted: 22 June 2018 / Published: 4 July 2018
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Abstract
In a demanding commercial world, large-scale chemical processes have been widely utilised to satisfy consumer related needs. Chemical industries are key to promoting economic growth and meeting the requirements of a sustainable industrialised society. The market need for diverse commodities produced by the
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In a demanding commercial world, large-scale chemical processes have been widely utilised to satisfy consumer related needs. Chemical industries are key to promoting economic growth and meeting the requirements of a sustainable industrialised society. The market need for diverse commodities produced by the chemical industry is rapidly expanding globally. Accompanying this demand is an increased threat to the environment and to human health, due to waste produced by increased industrial production. This increased demand has underscored the necessity to increase reaction efficiencies, in order to reduce costs and increase profits. The discovery of novel biocatalysts is a key method aimed at combating these difficulties. Metagenomic technology, as a tool for uncovering novel biocatalysts, has great potential and applicability and has already delivered many successful achievements. In this review we discuss, recent developments and achievements in the field of biocatalysis. We highlight how green chemistry principles through the application of biocatalysis, can be successfully promoted and implemented in various industrial sectors. In addition, we demonstrate how two novel lipases/esterases were mined from the marine environment by metagenomic analysis. Collectively these improvements can result in increased efficiency, decreased energy consumption, reduced waste and cost savings for the chemical industry. Full article
(This article belongs to the Special Issue Microbial Gene Clusters of Marine Origin)
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Open AccessArticle Sorbicillinoid-Based Metabolites from a Sponge-Derived Fungus Trichoderma saturnisporum
Mar. Drugs 2018, 16(7), 226; https://doi.org/10.3390/md16070226
Received: 8 June 2018 / Revised: 21 June 2018 / Accepted: 27 June 2018 / Published: 4 July 2018
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Abstract
Antibacterial activity assessment and high performance liquid chromatography associated with nuclear magnetic resonance (HPLC/NMR) data revealed that the EtOAc extract of the fermented endophytic fungus Trichoderma saturnisporum DI-IA, obtained from the marine sponge Dictyonella incisa, contained conjugated olefinic metabolites with antibacterial activity.
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Antibacterial activity assessment and high performance liquid chromatography associated with nuclear magnetic resonance (HPLC/NMR) data revealed that the EtOAc extract of the fermented endophytic fungus Trichoderma saturnisporum DI-IA, obtained from the marine sponge Dictyonella incisa, contained conjugated olefinic metabolites with antibacterial activity. Chemical examination of the fungal strain resulted in the isolation of eight new sorbicillinoid-based compounds, namely saturnispols A–H (18). Their structures were determined on the basis of extensive spectroscopic analysis, including the experimental and calculated electronic circular dichroism (ECD) data for the configurational assignments. Saturnispol F exerted significant inhibition against a panel of bacteria strains including vancomycin-resistant enterococci (VRE) with a minimum inhibitory concentrations (MIC) ranging from 1.63 to 12.9 μg/mL, while saturnispol H showed selective effects against VRE and B. subtilis. Full article
(This article belongs to the Special Issue Marine Natural Products from Symbiotic Ecosystems)
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Open AccessReview Marine Skeletons: Towards Hard Tissue Repair and Regeneration
Mar. Drugs 2018, 16(7), 225; https://doi.org/10.3390/md16070225
Received: 10 May 2018 / Revised: 25 June 2018 / Accepted: 28 June 2018 / Published: 2 July 2018
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Abstract
Musculoskeletal disorders in the elderly have significantly increased due to the increase in an ageing population. The treatment of these diseases necessitates surgical procedures, including total joint replacements such as hip and knee joints. Over the years a number of treatment options have
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Musculoskeletal disorders in the elderly have significantly increased due to the increase in an ageing population. The treatment of these diseases necessitates surgical procedures, including total joint replacements such as hip and knee joints. Over the years a number of treatment options have been specifically established which are either permanent or use temporary natural materials such as marine skeletons that possess unique architectural structure and chemical composition for the repair and regeneration of bone tissue. This review paper will give an overview of presently used materials and marine structures for hard tissue repair and regeneration, drugs of marine origin and other marine products which show potential for musculoskeletal treatment. Full article
(This article belongs to the Special Issue Marine Organisms for Bone Regeneration)
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Open AccessArticle Pufferfish Saxitoxin and Tetrodotoxin Binding Protein (PSTBP) Analogues in the Blood Plasma of the Pufferfish Arothron nigropunctatus, A. hispidus, A. manilensis, and Chelonodon patoca
Mar. Drugs 2018, 16(7), 224; https://doi.org/10.3390/md16070224
Received: 14 May 2018 / Revised: 13 June 2018 / Accepted: 22 June 2018 / Published: 29 June 2018
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Abstract
Pufferfish saxitoxin and tetrodotoxin (TTX) binding protein (PSTBP) is a glycoprotein that we previously isolated from the blood plasma of the pufferfish Takifugu pardalis; this protein was also detected in seven species of the genus Takifugu. We proposed that PSTBP is
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Pufferfish saxitoxin and tetrodotoxin (TTX) binding protein (PSTBP) is a glycoprotein that we previously isolated from the blood plasma of the pufferfish Takifugu pardalis; this protein was also detected in seven species of the genus Takifugu. We proposed that PSTBP is a carrier protein for TTX in pufferfish; however, PSTBP had not yet been found in genera other than Takifugu. In this study, we investigated the presence of PSTBP-like proteins in the toxic pufferfish Arothron nigropunctatus, A. hispidus, A. manilensis, and Chelonodon patoca. On the basis of ultrafiltration experiments, TTX was found to be present and partially bound to proteins in the plasma of these pufferfish, and Western blot analyses with anti-PSTBP antibody revealed one or two bands per species. The observed decreases in molecular mass following deglycosylation with glycopeptidase F suggest that these positive proteins are glycoproteins. The molecular masses of the deglycosylated proteins detected in the three Arothron species were larger than that of PSTBP in the genus Takifugu, whereas the two bands detected in C. patoca had molecular masses similar to that of tributyltin-binding protein-2 (TBT-bp2). The N-terminal amino acid sequences of 23–29 residues of these detected proteins were all homologous with those of PSTBP and TBT-bp2. Full article
(This article belongs to the Special Issue Tetrodotoxin)
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Open AccessArticle Elucidation of the Relationship between CD Cotton Effects and the Absolute Configuration of Sixteen Stereoisomers of Spiroheterocyclic-Lactams
Mar. Drugs 2018, 16(7), 223; https://doi.org/10.3390/md16070223
Received: 12 June 2018 / Revised: 24 June 2018 / Accepted: 27 June 2018 / Published: 29 June 2018
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As part of research to search for antitumor agents in fungi originating from marine organisms, cephalimysins E–L were isolated from a culture broth of Aspergillus fumigatus that was separated from the marine fish Mugil cephalus. One- and two-dimensional nuclear magnetic resonance spectra
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As part of research to search for antitumor agents in fungi originating from marine organisms, cephalimysins E–L were isolated from a culture broth of Aspergillus fumigatus that was separated from the marine fish Mugil cephalus. One- and two-dimensional nuclear magnetic resonance spectra revealed their planar structures, which are diastereomers of each other. Their absolute stereostructures were established by epimerization at C-8 with acidic methanol, nuclear Overhauser effect spectroscopy (NOESY), and circular dichroism (CD) spectroscopy. These demonstrated the detailed relationships between absolute configuration and CD Cotton effects. Additionally, in the growth inhibition assay against P388, HL-60, L1210, and KB cell lines, some of the fungal metabolites or reaction products exhibited moderate activities. Full article
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Open AccessArticle Physicochemical Properties and Biocompatibility Evaluation of Collagen from the Skin of Giant Croaker (Nibea japonica)
Mar. Drugs 2018, 16(7), 222; https://doi.org/10.3390/md16070222
Received: 28 May 2018 / Revised: 19 June 2018 / Accepted: 28 June 2018 / Published: 29 June 2018
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Abstract
Collagen and collagen peptides are widely used as cosmetic ingredients. In the present study, acid-solubilized collagen (ASC) and pepsin-solubilized collagen (PSC) were extracted from giant croaker (Nibea japonica) skin. The proline hydroxylation rates of ASC and PSC were 38.1% and 39.3%.
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Collagen and collagen peptides are widely used as cosmetic ingredients. In the present study, acid-solubilized collagen (ASC) and pepsin-solubilized collagen (PSC) were extracted from giant croaker (Nibea japonica) skin. The proline hydroxylation rates of ASC and PSC were 38.1% and 39.3%. The denaturation temperatures (Td) were approximately 34.5 °C for both ASC and PSC. The results of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and fourier transform infrared spetroscopy (FTIR) demonstrated that ASC and PSC were mainly type I collagen. Furthermore, As, Pb and Hg contents in the extracted collagen were lower than the national standards of China. In addition, collagen had good moisture absorption and retention properties when compared to glycerol. The collagen was also not cytotoxic to NIH-3T3 fibroblast cells, indicating that Nibea japonica skin collagen can be utilized in cosmetic applications. Full article
(This article belongs to the Special Issue Marine Resource and Cosmetics)
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Open AccessArticle Seaweed Extract (Stella Maris®) Activates Innate Immune Responses in Arabidopsis thaliana and Protects Host against Bacterial Pathogens
Mar. Drugs 2018, 16(7), 221; https://doi.org/10.3390/md16070221
Received: 4 June 2018 / Revised: 19 June 2018 / Accepted: 27 June 2018 / Published: 28 June 2018
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Abstract
Insects and pathogenic infections (bacteria, viruses and fungi) cause huge losses in agriculturally important crops yearly. Due to the rise in pesticide and antibiotic resistance, our crops and livestock are increasingly at risk. There is a rising demand for environmentally friendly solutions to
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Insects and pathogenic infections (bacteria, viruses and fungi) cause huge losses in agriculturally important crops yearly. Due to the rise in pesticide and antibiotic resistance, our crops and livestock are increasingly at risk. There is a rising demand for environmentally friendly solutions to prevent crop decreases. Components of Ascophyllum nodosum seaweed extracts were recently found to boost plant immunity. The stimulatory activities of the A.nodosum marine alga-derived extract (Stella Maris®) were investigated in a broad range of immune assays. Elevated hydrogen peroxide production measured in a chemiluminescence assay suggested that the extract elicited a strong burst of reactive oxygen species. Arabidopsis seedlings treated with Stella Maris® activated the expression of WRKY30, CYP71A12 and PR-1 genes, the induction of which represent early, mid and late plant immune response, respectively. Finally, this study found that Stella Maris® inhibited the growth of multiple bacterial pathogens, including an opportunistic human pathogen that has demonstrated pathogenicity in plants. In summary, the pre-treatment with the seaweed extract protected Arabidopsis against subsequent infection by these pathogens. Full article
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Open AccessArticle Cyanopeptolins with Trypsin and Chymotrypsin Inhibitory Activity from the Cyanobacterium Nostoc edaphicum CCNP1411
Mar. Drugs 2018, 16(7), 220; https://doi.org/10.3390/md16070220
Received: 5 June 2018 / Revised: 19 June 2018 / Accepted: 20 June 2018 / Published: 26 June 2018
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Cyanopeptolins (CPs) are one of the most frequently occurring cyanobacterial peptides, many of which are inhibitors of serine proteases. Some CP variants are also acutely toxic to aquatic organisms, especially small crustaceans. In this study, thirteen CPs, including twelve new variants, were detected
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Cyanopeptolins (CPs) are one of the most frequently occurring cyanobacterial peptides, many of which are inhibitors of serine proteases. Some CP variants are also acutely toxic to aquatic organisms, especially small crustaceans. In this study, thirteen CPs, including twelve new variants, were detected in the cyanobacterium Nostoc edaphicum CCNP1411 isolated from the Gulf of Gdańsk (southern Baltic Sea). Structural elucidation was performed by tandem mass spectrometry with verification by NMR for CP962 and CP985. Trypsin and chymotrypsin inhibition assays confirmed the significance of the residue adjacent to 3-amino-6-hydroxy-2-piperidone (Ahp) for the activity of the peptides. Arginine-containing CPs (CPs-Arg2) inhibited trypsin at low IC50 values (0.24–0.26 µM) and showed mild activity against chymotrypsin (IC50 3.1–3.8 µM), while tyrosine-containing CPs (CPs-Tyr2) were selectively and potently active against chymotrypsin (IC50 0.26 µM). No degradation of the peptides was observed during the enzyme assays. Neither of the CPs were active against thrombin, elastase or protein phosphatase 1. Two CPs (CP962 and CP985) had no cytotoxic effects on MCF-7 breast cancer cells. Strong and selective activity of the new cyanopeptolin variants makes them potential candidates for the development of drugs against metabolic disorders and other diseases. Full article
(This article belongs to the Special Issue Marine Bacterial Toxins)
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Open AccessArticle A Hetero-Photoautotrophic Two-Stage Cultivation Process for Production of Fucoxanthin by the Marine Diatom Nitzschia laevis
Mar. Drugs 2018, 16(7), 219; https://doi.org/10.3390/md16070219
Received: 25 May 2018 / Revised: 18 June 2018 / Accepted: 22 June 2018 / Published: 25 June 2018
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Abstract
There is currently much interest in fucoxanthin due to its broad beneficial health effects. The major commercial source of fucoxanthin is marine seaweed, which has many shortcomings, and has thus restricted its large-scale production and more diversified applications. In this study, growth characteristics
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There is currently much interest in fucoxanthin due to its broad beneficial health effects. The major commercial source of fucoxanthin is marine seaweed, which has many shortcomings, and has thus restricted its large-scale production and more diversified applications. In this study, growth characteristics and fucoxanthin accumulation were evaluated to explore the potential of the marine diatom Nitzschia laevis in fucoxanthin production. The results suggested that heterotrophic culture was more effective for cell growth, while the mixotrophic culture was favorable for fucoxanthin accumulation. A two-stage culture strategy was consequently established. A model of exponential fed-batch culture led to a biomass concentration of 17.25 g/L. A mix of white and blue light significantly increased fucoxanthin content. These outcomes were translated into a superior fucoxanthin productivity of 16.5 mg/(L·d), which was more than 2-fold of the best value reported thus far. The culture method established herein therefore represents a promising strategy to boost fucoxanthin production in N. laevis, which might prove to be a valuable natural source of commercial fucoxanthin. Full article
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Open AccessArticle The Positive Role of Curcumin-Loaded Salmon Nanoliposomes on the Culture of Primary Cortical Neurons
Mar. Drugs 2018, 16(7), 218; https://doi.org/10.3390/md16070218
Received: 10 April 2018 / Revised: 31 May 2018 / Accepted: 13 June 2018 / Published: 25 June 2018
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Curcumin (diferuloylmethane) is a natural bioactive compound with many health-promoting benefits. However, its poor water solubility and bioavailability has limited curcumin’s biomedical application. In the present study, we encapsulated curcumin into liposomes, formed from natural sources (salmon lecithin), and characterized its encapsulation efficiency
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Curcumin (diferuloylmethane) is a natural bioactive compound with many health-promoting benefits. However, its poor water solubility and bioavailability has limited curcumin’s biomedical application. In the present study, we encapsulated curcumin into liposomes, formed from natural sources (salmon lecithin), and characterized its encapsulation efficiency and release profile. The proposed natural carriers increased the solubility and the bioavailability of curcumin. In addition, various physico-chemical properties of the developed soft nanocarriers with and without curcumin were studied. Nanoliposome-encapsulated curcumin increased the viability and network formation in the culture of primary cortical neurons and decreased the rate of apoptosis. Full article
(This article belongs to the Special Issue Marine Drugs and Nanomedicine)
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