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Special Issue "Bioactivity of Marine Natural Products"

A special issue of International Journal of Molecular Sciences (ISSN 1422-0067). This special issue belongs to the section "Bioactives and Nutraceuticals".

Deadline for manuscript submissions: closed (30 October 2015)

Special Issue Editors

Guest Editor
Prof. Vassilios Roussis

Department of Pharmacognosy and Chemistry of Natural Products, Faculty of Pharmacy, National and Kapodistrian University of Athens, Panepistimiopolis Zografou, GR 15771, Athens, Greece
E-Mail
Phone: +30210 7274 592
Fax: +30 210 7274 592
Interests: marine natural products; chemotaxonomy; chemical ecology
Guest Editor
Assist. Prof. Efstathia Ioannou

Department of Pharmacognosy and Chemistry of Natural Products, Faculty of Pharmacy, School of Health Sciences, National and Kapodistrian University of Athens, Panepistimiopolis Zografou, Athens 15771, Greece
Website | E-Mail
Phone: +302107274913
Interests: marine natural products; structure elucidation; bioactivity evaluation; marine-derived microorganisms; biotransformations

Special Issue Information

Dear Colleagues,

Nature is the richest source of both biological and chemical diversity. Also, natural products still provide the majority of the world with their pharmacopoeia.

The marine environment, which represents approximately half of the global biodiversity, is estimated to have between 3 and 500 million different species; the environment represents an enormous resource for novel compounds.  However, the abundant floras and faunas inhabiting the 70% of the Earth’s surface that is covered by ocean still remains relatively unexplored.

More than 25,000 marine natural products have been discovered, with a marked increase in recent years. Most of the marine organisms have provided a seemingly endless parade of very unusual novel structures, often possessing functional groups appearing uniquely or predominantly in the marine environment. One particularly recurring feature is the presence of halogen atoms, which can be related to the relative abundance of these elements in the marine environment.

In the last decade the compounds Trabectedin  from the colonial tunicate Ecteinascidia turbinata and Ziconotide, the synthetic form of an ω-conotoxin peptide, from the cone snail Conus magus were approved for the treatment of advanced soft tissue sarcoma and the amelioration of severe and chronic pains, respectively. Besides them, through the combined efforts of marine natural product chemists and pharmacologists a number of promising compounds are already at advanced stages of clinical trials or have been selected as promising candidates.  Marine toxins produced in most cases by microorganisms, such as dinoflagellates or marine bacteria, represent one of the most challenging areas of marine chemistry and pharmacology.

This issue focuses on natural products derived from marine macro- and microorganisms with special emphasis on their biological activities and their potential as pharmaceuticals. Articles and mini reviews on ecological roles, structure-activity relationships, and reports of new bioactive marine metabolites are welcome.

Prof. Dr. Vassilios Roussis
Dr. Efstathia Ioannou
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. International Journal of Molecular Sciences is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

 

Keywords

  • Bioactive marine natural products
  • pharmacological activity
  • chemical ecology
  • antifouling activity
  • marine toxins
  • structure-activity relationships

Published Papers (9 papers)

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Research

Open AccessArticle New 9-Hydroxybriarane Diterpenoids from a Gorgonian Coral Briareum sp. (Briareidae)
Int. J. Mol. Sci. 2016, 17(1), 79; doi:10.3390/ijms17010079
Received: 30 November 2015 / Revised: 30 December 2015 / Accepted: 5 January 2016 / Published: 9 January 2016
Cited by 3 | PDF Full-text (1194 KB) | HTML Full-text | XML Full-text
Abstract
Six new 9-hydroxybriarane diterpenoids, briarenolides ZI–ZVI (16), were isolated from a gorgonian coral Briareum sp. The structures of briaranes 16 were elucidated by spectroscopic methods and by comparison of their spectroscopic data with those of related analogues.
[...] Read more.
Six new 9-hydroxybriarane diterpenoids, briarenolides ZI–ZVI (16), were isolated from a gorgonian coral Briareum sp. The structures of briaranes 16 were elucidated by spectroscopic methods and by comparison of their spectroscopic data with those of related analogues. Briarenolides ZII (2) and ZVI (6) were found to significantly inhibit the expression of the pro-inflammatory inducible nitric oxide synthase (iNOS) protein of lipopolysaccharide (LPS)-stimulated RAW264.7 macrophage cells. Full article
(This article belongs to the Special Issue Bioactivity of Marine Natural Products)
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Open AccessArticle The Use of a Liposomal Formulation Incorporating an Antimicrobial Peptide from Tilapia as a New Adjuvant to Epirubicin in Human Squamous Cell Carcinoma and Pluripotent Testicular Embryonic Carcinoma Cells
Int. J. Mol. Sci. 2015, 16(9), 22711-22734; doi:10.3390/ijms160922711
Received: 25 July 2015 / Revised: 9 September 2015 / Accepted: 11 September 2015 / Published: 18 September 2015
Cited by 5 | PDF Full-text (3582 KB) | HTML Full-text | XML Full-text
Abstract
This study aims to explore the effects and mechanisms of hepcidin, a potential antimicrobial peptide from Tilapia, and epirubicin (Epi), an antineoplastic agent, on the generation of reactive oxygen species (ROS) and link the ROS levels to the reversal mechanisms of multidrug resistance
[...] Read more.
This study aims to explore the effects and mechanisms of hepcidin, a potential antimicrobial peptide from Tilapia, and epirubicin (Epi), an antineoplastic agent, on the generation of reactive oxygen species (ROS) and link the ROS levels to the reversal mechanisms of multidrug resistance (MDR) by epirubicin and hepcidin in human squamous cell carcinoma SCC15 and human embryonal carcinoma NT2D1 cells. The cells, pretreated with hepcidin, epirubicin, or a combination of these compounds in PEGylated liposomes, were used to validate the molecular mechanisms involved in inhibiting efflux transporters and inducing apoptosis as evaluated by cytotoxicity, intracellular accumulation, mRNA levels, cell cycle distribution, and caspase activity of this combination. We found that hepcidin significantly enhanced the cytotoxicity of epirubicin in liposomes. The co-incubation of epirubicin with hepcidin in liposomes intensified the ROS production, including hydrogen peroxide and superoxide free radicals. Hepcidin significantly increased epirubicin intracellular uptake into NT2D1 and SCC15 cells, as supported by the diminished mRNA expressions of MDR1, MDR-associated protein (MRP) 1, and MRP2. Hepcidin and/or epirubicin in liposomes triggered apoptosis, as verified by the reduced mitochondrial membrane potential, increased sub-G1 phase of cell cycle, incremental populations of apoptosis using annexin V/PI assay, and chromatin condensation. As far as we know, this is the first example showing that PEGylated liposomal TH1-5 and epirubicin gives rise to cell death in human squamous carcinoma and testicular embryonic carcinoma cells through the reduced epirubicin efflux via ROS-mediated suppression of P-gp and MRPs and concomitant initiation of mitochondrial apoptosis pathway. Hence, hepcidin in PEGylated liposomes may function as an adjuvant to anticancer drugs, thus demonstrating a novel strategy for reversing MDR. Full article
(This article belongs to the Special Issue Bioactivity of Marine Natural Products)
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Open AccessArticle New Cytotoxic 24-Homoscalarane Sesterterpenoids from the Sponge Ircinia felix
Int. J. Mol. Sci. 2015, 16(9), 21950-21958; doi:10.3390/ijms160921950
Received: 7 August 2015 / Revised: 31 August 2015 / Accepted: 7 September 2015 / Published: 11 September 2015
Cited by 1 | PDF Full-text (764 KB) | HTML Full-text | XML Full-text
Abstract
Two new 24-homoscalarane sesterterpenoids, felixins F (1) and G (2), were isolated from the sponge Ircinia felix. The structures of new homoscalaranes 1 and 2 were elucidated by extensive spectroscopic methods, particularly with one-dimensional (1D) and two-dimensional (2D)
[...] Read more.
Two new 24-homoscalarane sesterterpenoids, felixins F (1) and G (2), were isolated from the sponge Ircinia felix. The structures of new homoscalaranes 1 and 2 were elucidated by extensive spectroscopic methods, particularly with one-dimensional (1D) and two-dimensional (2D) NMR, and, by comparison, the spectral data with those of known analogues. The cytotoxicity of 1 and 2 against the proliferation of a limited panel of tumor cell lines was evaluated and 1 was found to show cytotoxicity toward the leukemia K562, MOLT-4, and SUP-T1 cells (IC50 ≤ 5.0 μM). Full article
(This article belongs to the Special Issue Bioactivity of Marine Natural Products)
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Open AccessArticle 4-(Phenylsulfanyl)butan-2-One Suppresses Melanin Synthesis and Melanosome Maturation In Vitro and In Vivo
Int. J. Mol. Sci. 2015, 16(9), 20240-20257; doi:10.3390/ijms160920240
Received: 21 June 2015 / Revised: 12 August 2015 / Accepted: 12 August 2015 / Published: 26 August 2015
Cited by 8 | PDF Full-text (2587 KB) | HTML Full-text | XML Full-text
Abstract
In this study, we screened compounds with skin whitening properties and favorable safety profiles from a series of marine related natural products, which were isolated from Formosan soft coral Cladiella australis. Our results indicated that 4-(phenylsulfanyl)butan-2-one could successfully inhibit pigment generation processes
[...] Read more.
In this study, we screened compounds with skin whitening properties and favorable safety profiles from a series of marine related natural products, which were isolated from Formosan soft coral Cladiella australis. Our results indicated that 4-(phenylsulfanyl)butan-2-one could successfully inhibit pigment generation processes in mushroom tyrosinase platform assay, probably through the suppression of tyrosinase activity to be a non-competitive inhibitor of tyrosinase. In cell-based viability examinations, it demonstrated low cytotoxicity on melanoma cells and other normal human cells. It exhibited stronger inhibitions of melanin production and tyrosinase activity than arbutin or 1-phenyl-2-thiourea (PTU). Also, we discovered that 4-(phenylsulfanyl)butan-2-one reduces the protein expressions of melanin synthesis-related proteins, including the microphthalmia-associated transcription factor (MITF), tyrosinase-related protein-1 (Trp-1), dopachrome tautomerase (DCT, Trp-2), and glycoprotein 100 (GP100). In an in vivo zebrafish model, it presented a remarkable suppression in melanogenesis after 48 h. In summary, our in vitro and in vivo biological assays showed that 4-(phenylsulfanyl)butan-2-one possesses anti-melanogenic properties that are significant in medical cosmetology. Full article
(This article belongs to the Special Issue Bioactivity of Marine Natural Products)
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Open AccessArticle Terpenoids from the Octocoral Sinularia gaweli
Int. J. Mol. Sci. 2015, 16(8), 19508-19517; doi:10.3390/ijms160819508
Received: 8 July 2015 / Revised: 6 August 2015 / Accepted: 10 August 2015 / Published: 18 August 2015
Cited by 1 | PDF Full-text (1135 KB) | HTML Full-text | XML Full-text
Abstract
Two eudesmane sesquiterpenoids, verticillatol (1) and 5α-acetoxy-4(14)-eudesmene-1β-ol (2) and two cembrane diterpenoids, (–)-leptodiol acetate (3) and sinulacembranolide A (4) were isolated from the octocoral Sinularia gaweli and compounds 24 are new isolates. The
[...] Read more.
Two eudesmane sesquiterpenoids, verticillatol (1) and 5α-acetoxy-4(14)-eudesmene-1β-ol (2) and two cembrane diterpenoids, (–)-leptodiol acetate (3) and sinulacembranolide A (4) were isolated from the octocoral Sinularia gaweli and compounds 24 are new isolates. The structures of new terpenoids 24 were elucidated by spectroscopic methods and by comparison the spectral data with those of known analogues. Terpenoid 4 was found to inhibit the accumulation of the pro-inflammatory inducible nitric oxide synthase (iNOS) protein of the lipopolysaccharide (LPS)-stimulated RAW264.7 marcophage cells. Full article
(This article belongs to the Special Issue Bioactivity of Marine Natural Products)
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Open AccessArticle Anti-Angiogenic Properties of BDDPM, a Bromophenol from Marine Red Alga Rhodomela confervoides, with Multi Receptor Tyrosine Kinase Inhibition Effects
Int. J. Mol. Sci. 2015, 16(6), 13548-13560; doi:10.3390/ijms160613548
Received: 14 April 2015 / Revised: 21 May 2015 / Accepted: 29 May 2015 / Published: 12 June 2015
Cited by 3 | PDF Full-text (2051 KB) | HTML Full-text | XML Full-text
Abstract
Bis-(2,3-dibromo-4,5-dihydroxy-phenyl)-methane (BDDPM) is a bromophenol first isolated from Rhodomelaceae confervoides. Our previous studies showed that BDDPM exerts PTP1B-inhibiting activity and anti-cancer activity against a wide range of tumor cells while it also showed lower cytotoxicity against normal cells. In the present study,
[...] Read more.
Bis-(2,3-dibromo-4,5-dihydroxy-phenyl)-methane (BDDPM) is a bromophenol first isolated from Rhodomelaceae confervoides. Our previous studies showed that BDDPM exerts PTP1B-inhibiting activity and anti-cancer activity against a wide range of tumor cells while it also showed lower cytotoxicity against normal cells. In the present study, we found that BDDPM exhibits significant activities toward angiogenesis in vitro. BDDPM inhibits multiple angiogenesis processes, including endothelial cell sprouting, migration, proliferation, and tube formation. Further kinase assays investigations found that BDDPM is a potent selective, but multi-target, receptor tyrosine kinase (RTKs) inhibitor. BDDPM (10 μM) inhibits the activities of fibroblast growth factor receptor 2 and 3 (FGFR2, 3), vascular endothelial growth factor receptor 2 (VEGFR2) and platelet-derived growth factor receptor α (PDGFRα) (inhibition rate: 57.7%, 78.6%, 78.5% and 71.1%, respectively). Moreover, BDDPM also decreases the phosphorylation of protein kinase B (PKB/Akt) and endothelial nitric oxide synthase (eNOS), as well as nitric oxide (NO) production in a dose dependent manner. These results indicate that BDDPM can be exploited as an anti-angiogenic drug, or as a lead compound for the development of novel multi-target RTKs inhibitors. Full article
(This article belongs to the Special Issue Bioactivity of Marine Natural Products)
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Open AccessArticle Chitosan Oligosaccharides Inhibit/Disaggregate Fibrils and Attenuate Amyloid β-Mediated Neurotoxicity
Int. J. Mol. Sci. 2015, 16(5), 10526-10536; doi:10.3390/ijms160510526
Received: 6 March 2015 / Revised: 19 April 2015 / Accepted: 3 May 2015 / Published: 8 May 2015
Cited by 10 | PDF Full-text (2321 KB) | HTML Full-text | XML Full-text
Abstract
Alzheimer’s disease (AD) is characterized by a large number of amyloid-β (Aβ) deposits in the brain. Therefore, inhibiting Aβ aggregation or destabilizing preformed aggregates could be a promising therapeutic target for halting/slowing the progression of AD. Chitosan oligosaccharides (COS) have previously been reported
[...] Read more.
Alzheimer’s disease (AD) is characterized by a large number of amyloid-β (Aβ) deposits in the brain. Therefore, inhibiting Aβ aggregation or destabilizing preformed aggregates could be a promising therapeutic target for halting/slowing the progression of AD. Chitosan oligosaccharides (COS) have previously been reported to exhibit antioxidant and neuroprotective effects. Recent study shows that COS could markedly decrease oligomeric Aβ-induced neurotoxicity and oxidative stress in rat hippocampal neurons. However, the potential mechanism that COS reduce Aβ-mediated neurotoxicity remains unclear. In the present study, our findings from circular dichroism spectroscopy, transmission electron microscope and thioflavin T fluorescence assay suggested that COS act as an inhibitor of Aβ aggregation and this effect shows dose-dependency. Moreover, data from thioflavin T assay indicated that COS could significantly inhibit fibrils formation and disrupt preformed fibrils in a dose-dependent manner. Furthermore, the addition of COS attenuated Aβ1-42-induced neurotoxicity in rat cortical neurons. Taken together, our results demonstrated for the first time that COS could inhibit Aβ1-42 fibrils formation and disaggregate preformed fibrils, suggesting that COS may have anti-Aβ fibrillogenesis and fibril-destabilizing properties. These findings highlight the potential role of COS as novel therapeutic agents for the prevention and treatment of AD. Full article
(This article belongs to the Special Issue Bioactivity of Marine Natural Products)
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Open AccessArticle Dihydroaustrasulfone Alcohol (WA-25) Impedes Macrophage Foam Cell Formation by Regulating the Transforming Growth Factor-β1 Pathway
Int. J. Mol. Sci. 2015, 16(5), 10507-10525; doi:10.3390/ijms160510507
Received: 17 March 2015 / Revised: 22 April 2015 / Accepted: 29 April 2015 / Published: 7 May 2015
Cited by 5 | PDF Full-text (3434 KB) | HTML Full-text | XML Full-text
Abstract
Atherosclerosis is considered an inflammatory disease. However, clinically used anti-atherosclerotic drugs, such as simvastatin, have many side effects. Recently, several unique marine compounds have been isolated that possess a variety of bioactivities. In a previous study, we found a synthetic precursor of the
[...] Read more.
Atherosclerosis is considered an inflammatory disease. However, clinically used anti-atherosclerotic drugs, such as simvastatin, have many side effects. Recently, several unique marine compounds have been isolated that possess a variety of bioactivities. In a previous study, we found a synthetic precursor of the marine compound (austrasulfone), which is dihydroaustrasulfone alcohol (WA-25), has anti-atherosclerotic effects in vivo. However, the detailed mechanisms remain unclear. Therefore, to clarify the mechanisms through which WA-25 exerts anti-atherosclerotic activity, we used RAW 264.7 macrophages as an in vitro model to evaluate the effects of WA-25. In lipopolysaccharide (LPS)-stimulated RAW 264.7 cells, WA-25 significantly inhibited expression of the pro-inflammatory proteins, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). In contrast, simvastatin increased the COX-2 expression compared to WA-25. In addition, WA-25 impedes foam cell formation and up-regulated the lysosomal and cyclic adenosine monophosphate (cAMP) signaling pathway. We also observed that transforming growth factor β1 (TGF-β1) was up-regulated by WA-25 and simvastatin in LPS-induced RAW 264.7 cells, and the promising anti-atherosclerosis effects of WA-25 were disrupted by blockade of TGF-β1 signaling. Besides, WA-25 might act through increasing lipolysis than through alteration of lipid export. Taken together, these data demonstrate that WA-25 may have potential as an anti-atherosclerotic drug with anti-inflammatory effects. Full article
(This article belongs to the Special Issue Bioactivity of Marine Natural Products)
Open AccessCommunication Anti-Inflammatory Effect of Streptochlorin via TRIF-Dependent Signaling Pathways in Cellular and Mouse Models
Int. J. Mol. Sci. 2015, 16(4), 6902-6910; doi:10.3390/ijms16046902
Received: 10 February 2015 / Revised: 7 March 2015 / Accepted: 16 March 2015 / Published: 26 March 2015
Cited by 3 | PDF Full-text (1565 KB) | HTML Full-text | XML Full-text
Abstract
Streptochlorin, a small compound derived from marine actinomycete, has been shown to have anti-angiogenic, anti-tumor, and anti-allergic activities. However, the anti-inflammatory effects and underlying mechanisms have not yet been reported. In the present study, we investigated the effect of streptochlorin on lipopolysaccharide (LPS)-induced
[...] Read more.
Streptochlorin, a small compound derived from marine actinomycete, has been shown to have anti-angiogenic, anti-tumor, and anti-allergic activities. However, the anti-inflammatory effects and underlying mechanisms have not yet been reported. In the present study, we investigated the effect of streptochlorin on lipopolysaccharide (LPS)-induced inflammatory responses in vitro and in vivo. Streptochlorin attenuated the production of proinflammatory mediators such as nitric oxide, cyclooxygenase-2, pro-interleukin (IL)-1β, and IL-6 in LPS-stimulated RAW264.7 cells through inhibition of the Toll/interleukin-1 receptor (TIR)-domain-containing adapter-inducing interferon-β (TRIF)-dependent signaling pathway. Furthermore, streptochlorin suppressed the infiltration of immune cells such as neutrophils into the lung and proinflammatory cytokine production such as IL-6 and TNF-α in broncho-alveolar lavage fluid (BALF) in the LPS-induced acute lung injury (ALI) mouse model. Streptochlorin has potent anti-inflammatory effects through regulating TRIF-dependent signaling pathways, suggesting that streptochlorin may provide a valuable therapeutic strategy in treating various inflammatory diseases. Full article
(This article belongs to the Special Issue Bioactivity of Marine Natural Products)
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