Special Issue "Selected Papers from XVI MaNaPro and XI ECMNP"

A special issue of Marine Drugs (ISSN 1660-3397).

Deadline for manuscript submissions: 30 September 2020.

Special Issue Editors

Dr. Susana P Gaudencio
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Guest Editor
Department of Chemistry, New University of Lisbon, Portugal
Special Issues and Collections in MDPI journals
Prof. Dr. Rui Pedrosa
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Guest Editor
MARE – Marine and Environmental Sciences Centre, Polytechnic of Leiria, Portugal
Interests: marine biotechnology; marine drug discovery; cellular pharmacology and cellular biology
Prof. Dr. Vitor Manuel Oliveira Vasconcelos
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Guest Editor
Centro Interdisciplinar de Investigaco Marinha e Ambiental - CIIMAR/CIMAR-LA, Porto, Portugal
Interests: cyanobacteria; toxins; cyanotoxins; marine biotechnology; secondary metabolites; cyanobacterial blooms; ecotoxicology; environmental contamination
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

On behalf of the Organizing Committee for the XVI MaNaPro and XI ECMNP, we would like to cordially invite you to the ‘must-attend’ conference of 2019: the XVI International Symposium on Marine Natural Products and XV European Congress on Marine Natural Products joint meeting, http://wmnp2019.ipleiria.pt/, to be held in Peniche, Portugal, from September 1st to 5th, 2019.

Young scientists in the marine natural products (MNP) field from all over the world are especially encouraged to participate. Senior experts, rising MNP stars and early scientists will present their results in a combination of plenary lectures, contributed oral communications, and poster sessions.

The joint XVI MaNaPro and XI ECMNP meeting includes the following topics:

  • Isolation and structure elucidation of marine natural products;
  • Biosynthesis and chemical synthesis of marine natural products;
  • Marine chemical ecology and ecosystem functioning;
  • Marine natural products in chemical biology and biotechnology;
  • Drug discovery and development.

To maximize the impact of this conference to the marine natural products community, the chairs of this conference are organizing a Special Issue of Marine Drugs dedicated to this symposium entitled “Selected Papers from the XVI MaNaPro and XI ECMNP”. We kindly invite the attendees to contribute manuscripts for research papers or reviews for this Special Issue of Marine Drugs.

* Each submission will enjoy a 20% discount on APC, after accepted.

Dr. Susana P. Gaudencio
Prof. Dr. Rui Pedrosa
Prof. Dr. Vitor Vasconcelos
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. Marine Drugs 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 2000 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.

Published Papers (11 papers)

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Open AccessFeature PaperArticle
The Advanced Floating Chirality Distance Geometry Approach―How Anisotropic NMR Parameters Can Support the Determination of the Relative Configuration of Natural Products
Mar. Drugs 2020, 18(6), 330; https://doi.org/10.3390/md18060330 - 24 Jun 2020
Abstract
The configurational analysis of complex natural products by NMR spectroscopy is still a challenging task. The assignment of the relative configuration is usually carried out by analysis of interproton distances from NOESY or ROESY spectra (qualitative or quantitative) and scalar (J) [...] Read more.
The configurational analysis of complex natural products by NMR spectroscopy is still a challenging task. The assignment of the relative configuration is usually carried out by analysis of interproton distances from NOESY or ROESY spectra (qualitative or quantitative) and scalar (J) couplings. About 15 years ago, residual dipolar couplings (RDCs) were introduced as a tool for the configurational determination of small organic molecules. In contrast to NOEs/ROEs which are local parameters (distances up to 400 pm can be detected for small organic molecules), RDCs are global parameters which allow to obtain structural information also from long-range relationships. RDCs have the disadvantage that the sample needs a setup in an alignment medium in order to obtain the required anisotropic environment. Here, we will discuss the configurational analysis of five complex natural products: axinellamine A (1), tetrabromostyloguanidine (2), 3,7-epi-massadine chloride (3), tubocurarine (4), and vincristine (5). Compounds 13 are marine natural products whereas 4 and 5 are from terrestrial sources. The chosen examples will carefully work out the limitations of NOEs/ROEs in the configurational analysis of natural products and will also provide an outlook on the information obtained from RDCs. Full article
(This article belongs to the Special Issue Selected Papers from XVI MaNaPro and XI ECMNP)
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Open AccessArticle
Light-Mediated Toxicity of Porphyrin-Like Pigments from a Marine Polychaeta
Mar. Drugs 2020, 18(6), 302; https://doi.org/10.3390/md18060302 - 06 Jun 2020
Abstract
Porphyrins and derivatives form one of the most abundant classes of biochromes. They result from the breakdown of heme and have crucial physiological functions. Bilins are well-known representatives of this group that, besides significant antioxidant and anti-mutagenic properties, are also photosensitizers for photodynamic [...] Read more.
Porphyrins and derivatives form one of the most abundant classes of biochromes. They result from the breakdown of heme and have crucial physiological functions. Bilins are well-known representatives of this group that, besides significant antioxidant and anti-mutagenic properties, are also photosensitizers for photodynamic therapies. Recently, we demonstrated that the Polychaeta Eulalia viridis, common in the Portuguese rocky intertidal, holds a high variety of novel greenish and yellowish porphyrinoid pigments, stored as granules in the chromocytes of several organs. On the follow-up of this study, we chemically characterized pigment extracts from the worm’s skin and proboscis using HPLC and evaluated their light and dark toxicity in vivo and ex vivo using Daphnia and mussel gill tissue as models, respectively. The findings showed that the skin and proboscis have distinct patterns of hydrophilic or even amphiphilic porphyrinoids, with some substances in common. The combination of the two bioassays demonstrated that the extracts from the skin exert higher dark toxicity, whereas those from the proboscis rapidly exert light toxicity, then becoming exhausted. One particular yellow pigment that is highly abundant in the proboscis shows highly promising properties as a natural photosensitizer, revealing that porphyrinoids from marine invertebrates are important sources of these high-prized bioproducts. Full article
(This article belongs to the Special Issue Selected Papers from XVI MaNaPro and XI ECMNP)
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Open AccessArticle
Uncovering the Core Microbiome and Distribution of Palmerolide in Synoicum adareanum Across the Anvers Island Archipelago, Antarctica
Mar. Drugs 2020, 18(6), 298; https://doi.org/10.3390/md18060298 - 02 Jun 2020
Abstract
Polar marine ecosystems hold the potential for bioactive compound biodiscovery, based on their untapped macro- and microorganism diversity. Characterization of polar benthic marine invertebrate-associated microbiomes is limited to few studies. This study was motivated by our interest in better understanding the microbiome structure [...] Read more.
Polar marine ecosystems hold the potential for bioactive compound biodiscovery, based on their untapped macro- and microorganism diversity. Characterization of polar benthic marine invertebrate-associated microbiomes is limited to few studies. This study was motivated by our interest in better understanding the microbiome structure and composition of the ascidian, Synoicum adareanum, in which palmerolide A (PalA), a bioactive macrolide with specificity against melanoma, was isolated. PalA bears structural resemblance to a hybrid nonribosomal peptide-polyketide that has similarities to microbially-produced macrolides. We conducted a spatial survey to assess both PalA levels and microbiome composition in S. adareanum in a region of the Antarctic Peninsula near Anvers Island (64°46′ S, 64°03′ W). PalA was ubiquitous and abundant across a collection of 21 ascidians (3 subsamples each) sampled from seven sites across the Anvers Island Archipelago. The microbiome composition (V3–V4 16S rRNA gene sequence variants) of these 63 samples revealed a core suite of 21 bacterial amplicon sequence variants (ASVs)—20 of which were distinct from regional bacterioplankton. ASV co-occurrence analysis across all 63 samples yielded subgroups of taxa that may be interacting biologically (interacting subsystems) and, although the levels of PalA detected were not found to correlate with specific sequence variants, the core members appeared to occur in a preferred optimum and tolerance range of PalA levels. These results, together with an analysis of the biosynthetic potential of related microbiome taxa, describe a conserved, high-latitude core microbiome with unique composition and substantial promise for natural product biosynthesis that likely influences the ecology of the holobiont. Full article
(This article belongs to the Special Issue Selected Papers from XVI MaNaPro and XI ECMNP)
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Open AccessArticle
Anti-Fouling Effects of Saponin-Containing Crude Extracts from Tropical Indo-Pacific Sea Cucumbers
Mar. Drugs 2020, 18(4), 181; https://doi.org/10.3390/md18040181 - 31 Mar 2020
Abstract
Sea cucumbers are bottom dwelling invertebrates, which are mostly found on subtropical and tropical sea grass beds, sandy reef flats, or reef slopes. Although constantly exposed to fouling communities in these habitats, many species are surprisingly free of invertebrate epibionts and microfouling algae [...] Read more.
Sea cucumbers are bottom dwelling invertebrates, which are mostly found on subtropical and tropical sea grass beds, sandy reef flats, or reef slopes. Although constantly exposed to fouling communities in these habitats, many species are surprisingly free of invertebrate epibionts and microfouling algae such as diatoms. In our study, we investigated the anti-fouling (AF) activities of different crude extracts of tropical Indo-Pacific sea cucumber species against the fouling diatom Cylindrotheca closterium. Nine sea cucumber species from three genera (i.e., Holothuria, Bohadschia, Actinopyga) were selected and extracted to assess their AF activities. To verify whether the sea cucumber characteristic triterpene glycosides were responsible for the observed potent AF activities, we tested purified fractions enriched in saponins isolated from Bohadschia argus, representing one of the most active anti-fouling extracts. Saponins were quantified by vanillin-sulfuric acid colorimetric assays and identified by LC-MS and LC-MS/MS analyses. We were able to demonstrate that AF activities in sea cucumber extracts were species-specific, and growth inhibition as well as attachment of the diatom to surfaces is dependent on the saponin concentration (i.e., Actinopyga contained the highest quantities), as well as on the molecular composition and structure of the present saponins (i.e., Bivittoside D derivative was the most bioactive compound). In conclusion, the here performed AF assay represents a promising and fast method for selecting the most promising bioactive organism as well as for identifying novel compounds with potent AF activities for the discovery of potentially novel pharmacologically active natural products. Full article
(This article belongs to the Special Issue Selected Papers from XVI MaNaPro and XI ECMNP)
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Open AccessArticle
A Phenotarget Approach for Identifying an Alkaloid Interacting with the Tuberculosis Protein Rv1466
Mar. Drugs 2020, 18(3), 149; https://doi.org/10.3390/md18030149 - 05 Mar 2020
Cited by 1
Abstract
In recent years, there has been a revival of interest in phenotypic-based drug discovery (PDD) due to target-based drug discovery (TDD) falling below expectations. Both PDD and TDD have their unique advantages and should be used as complementary methods in drug discovery. The [...] Read more.
In recent years, there has been a revival of interest in phenotypic-based drug discovery (PDD) due to target-based drug discovery (TDD) falling below expectations. Both PDD and TDD have their unique advantages and should be used as complementary methods in drug discovery. The PhenoTarget approach combines the strengths of the PDD and TDD approaches. Phenotypic screening is conducted initially to detect cellular active components and the hits are then screened against a panel of putative targets. This PhenoTarget protocol can be equally applied to pure compound libraries as well as natural product fractions. Here we described the use of the PhenoTarget approach to identify an anti-tuberculosis lead compound. Fractions from Polycarpa aurata were identified with activity against Mycobacterium tuberculosis H37Rv. Native magnetic resonance mass spectrometry (MRMS) against a panel of 37 proteins from Mycobacterium proteomes showed that a fraction from a 95% ethanol re-extraction specifically formed a protein-ligand complex with Rv1466, a putative uncharacterized Mycobacterium tuberculosis protein. The natural product responsible was isolated and characterized to be polycarpine. The molecular weight of the ligand bound to Rv1466, 233 Da, was half the molecular weight of polycarpine less one proton, indicating that polycarpine formed a covalent bond with Rv1466. Full article
(This article belongs to the Special Issue Selected Papers from XVI MaNaPro and XI ECMNP)
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Open AccessArticle
Investigating the Antiparasitic Potential of the Marine Sesquiterpene Avarone, Its Reduced Form Avarol, and the Novel Semisynthetic Thiazinoquinone Analogue Thiazoavarone
Mar. Drugs 2020, 18(2), 112; https://doi.org/10.3390/md18020112 - 14 Feb 2020
Cited by 1
Abstract
The chemical analysis of the sponge Dysidea avara afforded the known sesquiterpene quinone avarone, along with its reduced form avarol. To further explore the role of the thiazinoquinone scaffold as an antiplasmodial, antileishmanial and antischistosomal agent, we converted the quinone avarone into the [...] Read more.
The chemical analysis of the sponge Dysidea avara afforded the known sesquiterpene quinone avarone, along with its reduced form avarol. To further explore the role of the thiazinoquinone scaffold as an antiplasmodial, antileishmanial and antischistosomal agent, we converted the quinone avarone into the thiazinoquinone derivative thiazoavarone. The semisynthetic compound, as well as the natural metabolites avarone and avarol, were pharmacologically investigated in order to assess their antiparasitic properties against sexual and asexual stages of Plasmodium falciparum, larval and adult developmental stages of Schistosoma mansoni (eggs included), and also against promastigotes and amastigotes of Leishmania infantum and Leishmania tropica. Furthermore, in depth computational studies including density functional theory (DFT) calculations were performed. A toxic semiquinone radical species which can be produced starting both from quinone- and hydroquinone-based compounds could mediate the anti-parasitic effects of the tested compounds. Full article
(This article belongs to the Special Issue Selected Papers from XVI MaNaPro and XI ECMNP)
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Open AccessArticle
Antifouling Napyradiomycins from Marine-Derived Actinomycetes Streptomyces aculeolatus
Mar. Drugs 2020, 18(1), 63; https://doi.org/10.3390/md18010063 - 18 Jan 2020
Cited by 2
Abstract
The undesired attachment of micro and macroorganisms on water-immersed surfaces, known as marine biofouling, results in severe prevention and maintenance costs (billions €/year) for aquaculture, shipping and other industries that rely on coastal and off-shore infrastructures. To date, there are no sustainable, cost-effective [...] Read more.
The undesired attachment of micro and macroorganisms on water-immersed surfaces, known as marine biofouling, results in severe prevention and maintenance costs (billions €/year) for aquaculture, shipping and other industries that rely on coastal and off-shore infrastructures. To date, there are no sustainable, cost-effective and environmentally safe solutions to address this challenging phenomenon. Therefore, we investigated the antifouling activity of napyradiomycin derivatives that were isolated from actinomycetes from ocean sediments collected off the Madeira Archipelago. Our results revealed that napyradiomycins inhibited ≥80% of the marine biofilm-forming bacteria assayed, as well as the settlement of Mytilus galloprovincialis larvae (EC50 < 5 µg/ml and LC50/EC50 >15), without viability impairment. In silico prediction of toxicity end points are of the same order of magnitude of standard approved drugs and biocides. Altogether, napyradiomycins disclosed bioactivity against marine micro and macrofouling organisms, and non-toxic effects towards the studied species, displaying potential to be used in the development of antifouling products. Full article
(This article belongs to the Special Issue Selected Papers from XVI MaNaPro and XI ECMNP)
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Open AccessArticle
Ubiquitin-Proteasome Modulating Dolabellanes and Secosteroids from Soft Coral Clavularia flava
Mar. Drugs 2020, 18(1), 39; https://doi.org/10.3390/md18010039 - 03 Jan 2020
Abstract
We performed a high-content screening (HCS) assay aiming to discover bioactive molecules with proteasome inhibitory activity. By structural elucidation, we identified six compounds purified from soft coral Clavularia flava, which potentiates proteasome inhibition. Chemical structure elucidation revealed they are dolabellane- and secosteroid-based [...] Read more.
We performed a high-content screening (HCS) assay aiming to discover bioactive molecules with proteasome inhibitory activity. By structural elucidation, we identified six compounds purified from soft coral Clavularia flava, which potentiates proteasome inhibition. Chemical structure elucidation revealed they are dolabellane- and secosteroid-based compounds including a new dolabellane, clavinflol C (1), three known dolabellanes, stolonidiol (2), stolonidiol-17-acetate (3), and clavinflol B (4) as well as two new secosteroids, 3β,11-dihydroxy-24-methyl-9,11-secocholest-5-en-9,23-dione (5) and 3β,11-dihydroxy-24-methylene-9,11-secocholest-5-en-9,23-dione (6). All six compounds show less cytotoxicity than those of known proteasome inhibitors, bortezomib and MG132. In summary, the high-content measurements of control inhibitors, bortezomib and MG132, manifest the highest ratio >2 in high-content measurement. Of the isolated compounds, 2 and 5 showed higher activity, followed by 3 and 6, and then 1 and 4 exhibited moderate inhibition. Full article
(This article belongs to the Special Issue Selected Papers from XVI MaNaPro and XI ECMNP)
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Open AccessArticle
New Benthic Cyanobacteria from Guadeloupe Mangroves as Producers of Antimicrobials
Mar. Drugs 2020, 18(1), 16; https://doi.org/10.3390/md18010016 - 23 Dec 2019
Abstract
Benthic cyanobacteria strains from Guadeloupe have been investigated for the first time by combining phylogenetic, chemical and biological studies in order to better understand the taxonomic and chemical diversity as well as the biological activities of these cyanobacteria through the effect of their [...] Read more.
Benthic cyanobacteria strains from Guadeloupe have been investigated for the first time by combining phylogenetic, chemical and biological studies in order to better understand the taxonomic and chemical diversity as well as the biological activities of these cyanobacteria through the effect of their specialized metabolites. Therefore, in addition to the construction of the phylogenetic tree, indicating the presence of 12 potentially new species, an LC-MS/MS data analysis workflow was applied to provide an overview on chemical diversity of 20 cyanobacterial extracts, which was linked to antimicrobial activities evaluation against human pathogenic and ichtyopathogenic environmental strains. Full article
(This article belongs to the Special Issue Selected Papers from XVI MaNaPro and XI ECMNP)
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Open AccessArticle
Biologically Active Metabolites from the Marine Sediment-Derived Fungus Aspergillus flocculosus
Mar. Drugs 2019, 17(10), 579; https://doi.org/10.3390/md17100579 - 11 Oct 2019
Cited by 1
Abstract
Four new compounds were isolated from the Vietnamese marine sediment-derived fungus Aspergillus flocculosus, one aspyrone-related polyketide aspilactonol G (2), one meroterpenoid 12-epi-aspertetranone D (4), two drimane derivatives (7,9), together with five known metabolites ( [...] Read more.
Four new compounds were isolated from the Vietnamese marine sediment-derived fungus Aspergillus flocculosus, one aspyrone-related polyketide aspilactonol G (2), one meroterpenoid 12-epi-aspertetranone D (4), two drimane derivatives (7,9), together with five known metabolites (1,3,5,6,8,10). The structures of compounds 110 were established by NMR and MS techniques. The absolute stereoconfigurations of compounds 1 and 2 were determined by a modified Mosher’s method. The absolute configurations of compounds 4 and 7 were established by a combination of analysis of ROESY data and coupling constants as well as biogenetic considerations. Compounds 7 and 8 exhibited cytotoxic activity toward human prostate cancer 22Rv1, human breast cancer MCF-7, and murine neuroblastoma Neuro-2a cells. Full article
(This article belongs to the Special Issue Selected Papers from XVI MaNaPro and XI ECMNP)
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Open AccessConference Report
XVI International Symposium on Marine Natural Products|XI European Conference on Marine Natural Products
Mar. Drugs 2020, 18(1), 40; https://doi.org/10.3390/md18010040 - 06 Jan 2020
Abstract
The International Symposium on Marine Natural Products (MaNaPro) happened for the first time in 1975 in the city of Aberdeen, Scotland, organized by Professor Ronald H [...] Full article
(This article belongs to the Special Issue Selected Papers from XVI MaNaPro and XI ECMNP)
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