Special Issue "Marine Natural Product of the South Pacific Area"

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

Deadline for manuscript submissions: closed (31 December 2020).

Special Issue Editors

Dr. Sylvain Petek
E-Mail Website
Guest Editor
IRD, Univ Brest, CNRS, Ifremer, LEMAR, F-29280 Plouzane, France
Interests: marine invertebrates; natural product extraction; natural product isolation; bioactive compounds; chemotaxonomy; quorum sensing; anticancer and anti-infective agents; scientific database
Dr. Cécile Debitus
E-Mail
Guest Editor
IRD, Univ Brest, CNRS, Ifremer, LEMAR, F-29280 Plouzane, France
Interests: marine invertebrates; natural products extraction; natural product isolation; bioactive compounds; chemotaxonomy; quorum sensing; anticancer drugs
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

The South Pacific is a huge region but is often seen only in its tropical and coral reef aspects of the Oceania part. However, it includes temperate Oceania and the Pacific Antarctica regions and a great part of the western coast of South America. The South Pacific offers a tiny portion of inhabited, enclosed land compared to the vastness of the ocean. The tropical islands, being either continental relics such as part of Melanesia, or of volcanic origin such as the Polynesian Islands, display protective coral reefs that are home to a great diversity of flora and fauna, offering an incredible treasure trove of natural products. The cold and deep environments are not to be outdone: In addition to a rich bathyal and abyssal fauna, these biotopes offer a mine of microorganisms with an important biotechnological potential.

This Special Issue dedicated to the South Pacific offers researchers the opportunity to publish their original work in a large number of fields: natural products of fauna and flora, but also of microorganisms, presenting biological activities in a large number of domains, whether for health, environmental, or biotechnological applications. Since the huge array of species gives us the opportunity to discover key minor compounds in biosynthetic pathways, allowing their understanding, biomimetic syntheses, which are of a great interest in the actual context of blue chemistry, are also welcome in this issue.

Dr. Sylvain Petek
Dr. Cécile Debitus
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 2400 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

  • South Pacific
  • Pacific–Antarctic
  • bioactive metabolites
  • biotechnological applications
  • natural products
  • toxins

Published Papers (7 papers)

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Research

Open AccessArticle
Bioactive Bromotyrosine Derivatives from the Pacific Marine Sponge Suberea clavata (Pulitzer-Finali, 1982)
Mar. Drugs 2021, 19(3), 143; https://doi.org/10.3390/md19030143 - 06 Mar 2021
Viewed by 565
Abstract
Chemical investigation of the South-Pacific marine sponge Suberea clavata led to the isolation of eight new bromotyrosine metabolites named subereins 1–8 (29) along with twelve known co-isolated congeners. The detailed configuration determination of the first representative major compound of [...] Read more.
Chemical investigation of the South-Pacific marine sponge Suberea clavata led to the isolation of eight new bromotyrosine metabolites named subereins 1–8 (29) along with twelve known co-isolated congeners. The detailed configuration determination of the first representative major compound of this family 11-epi-fistularin-3 (11R,17S) (1) is described. Their chemical characterization was achieved by HRMS and integrated 1D and 2D NMR (nuclear magnetic resonance) spectroscopic studies and extensive comparison with literature data. For the first time, a complete assignment of the absolute configurations for stereogenic centers C-11/17 of the known members (11R,17S) 11-epi-fistularin-3 (1) and 17-deoxyfistularin-3 (10) was determined by a combination of chemical modifications, Mosher’s technology, and ECD spectroscopy. Consequently, the absolute configurations of all our new isolated compounds 29 were determined by the combination of NMR, Mosher’s method, ECD comparison, and chemical modifications. Interestingly, compounds 27 were obtained by chemical transformation of the major compound 11-epi-fistularin-3 (1). Evaluation for acetylcholinesterase inhibition (AChE), DNA methyltransferase 1 (DNMT1) modulating activity and antifouling activities using marine bacterial strains are also presented. Full article
(This article belongs to the Special Issue Marine Natural Product of the South Pacific Area)
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Open AccessArticle
Tedaniophorbasins A and B—Novel Fluorescent Pteridine Alkaloids Incorporating a Thiomorpholine from the Sponge Tedaniophorbas ceratosis
Mar. Drugs 2021, 19(2), 95; https://doi.org/10.3390/md19020095 - 07 Feb 2021
Cited by 1 | Viewed by 665
Abstract
Two new fluorescent pteridine alkaloids, tedaniophorbasins A (1) and B (2), together with the known alkaloid N-methyltryptamine, were isolated, through application of mass directed purification, from the sponge Tedaniophorbas ceratosis collected from northern New South Wales, Australia. The [...] Read more.
Two new fluorescent pteridine alkaloids, tedaniophorbasins A (1) and B (2), together with the known alkaloid N-methyltryptamine, were isolated, through application of mass directed purification, from the sponge Tedaniophorbas ceratosis collected from northern New South Wales, Australia. The structures of tedaniophorbasins A and B were deduced from the analysis of 1D/2D NMR and MS data and through application of 13C NMR DFT calculations. Tedaniophorbasin A possesses a novel 2-imino-1,3-dimethyl-2,3,7,8-tetrahydro-1H-[1,4]thiazino[3,2-g]pteridin-4(6H)-one skeleton, while tedaniophorbasin B is its 2-oxo derivative. The compounds show significant Stokes shifts (~14,000 cm−1) between excitation and emission wavelengths in their fluorescence spectra. The new compounds were tested for bioactivity against chloroquine-sensitive and chloroquine-resistant strains of the malaria parasite Plasmodium falciparum, breast and pancreatic cancer cell lines, and the protozoan parasite Trypanosoma brucei brucei but were inactive against all targets at 40 µM. Full article
(This article belongs to the Special Issue Marine Natural Product of the South Pacific Area)
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Open AccessArticle
Effects of Nitrogen Availability on the Antioxidant Activity and Carotenoid Content of the Microalgae Nephroselmis sp
Mar. Drugs 2020, 18(9), 453; https://doi.org/10.3390/md18090453 - 29 Aug 2020
Viewed by 783
Abstract
Nephroselmis sp. was previously identified as a species of interest for its antioxidant properties owing to its high carotenoid content. In addition, nitrogen availability can impact biomass and specific metabolites’ production of microalgae. To optimize parameters of antioxidant production, Nephroselmis sp. was cultivated [...] Read more.
Nephroselmis sp. was previously identified as a species of interest for its antioxidant properties owing to its high carotenoid content. In addition, nitrogen availability can impact biomass and specific metabolites’ production of microalgae. To optimize parameters of antioxidant production, Nephroselmis sp. was cultivated in batch and continuous culture conditions in stirred closed photobioreactors under different nitrogen conditions (N-repletion, N-limitation, and N-starvation). The aim was to determine the influence of nitrogen availability on the peroxyl radical scavenging activity (oxygen radical absorbance capacity (ORAC) assay) and carotenoid content of Nephroselmis sp. Pigment analysis revealed a specific and unusual photosynthetic system with siphonaxanthin-type light harvesting complexes found in primitive green algae, but also high lutein content and xanthophyll cycle pigments (i.e., violaxanthin, antheraxanthin, and zeaxanthin), as observed in most advanced chlorophytes. The results indicated that N-replete conditions enhance carotenoid biosynthesis, which would correspond to a higher antioxidant capacity measured in Nephroselmis sp. Indeed, peroxyl radical scavenging activity and total carotenoids were higher under N-replete conditions and decreased sharply under N-limitation or starvation conditions. Considering individual carotenoids, siphonaxanthin, neoxanthin, xanthophyll cycle pigments, and lycopene followed the same trend as total carotenoids, while β-carotene and lutein stayed stable regardless of the nitrogen availability. Carotenoid productivities were also higher under N-replete treatment. The peroxyl radical scavenging activity measured with ORAC assay (63.6 to 154.9 µmol TE g−1 DW) and the lutein content (5.22 to 7.97 mg g−1 DW) were within the upper ranges of values reported previously for other microalgae. Furthermore, contents of siphonaxanthin ere 6 to 20% higher than in previous identified sources (siphonous green algae). These results highlight the potential of Nephroselmis sp. as a source of natural antioxidant and as a pigment of interest. Full article
(This article belongs to the Special Issue Marine Natural Product of the South Pacific Area)
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Open AccessFeature PaperArticle
Exploration of the Electrophilic Reactivity of the Cytotoxic Marine Alkaloid Discorhabdin C and Subsequent Discovery of a New Dimeric C-1/N-13-Linked Discorhabdin Natural Product
Mar. Drugs 2020, 18(8), 404; https://doi.org/10.3390/md18080404 - 31 Jul 2020
Cited by 2 | Viewed by 798
Abstract
The cytotoxic marine natural product discorhabdin C contains a 2,6-dibromo-cyclohexa-2,5-diene moiety, previously proposed to be a critical feature required for biological activity. We have determined that the dienone-ring of discorhabdin C is indeed electrophilic, reacting with thiol and amine nucleophiles, affording debrominated adducts. [...] Read more.
The cytotoxic marine natural product discorhabdin C contains a 2,6-dibromo-cyclohexa-2,5-diene moiety, previously proposed to be a critical feature required for biological activity. We have determined that the dienone-ring of discorhabdin C is indeed electrophilic, reacting with thiol and amine nucleophiles, affording debrominated adducts. In the case of reaction with 1-aminopentane the product contains an unusual C-2/N-18 ring closed, double-hydrate moiety. This electrophilic reactivity also extends to proteins, with lysozyme-discorhabdin C adducts being detected by ESI mass spectrometry. These results prompted further examination of an extract of discorhabdin C-producing sponge, Latrunculia (Latrunculia) trivetricillata, leading to the isolation and characterisation of a new example of a C-1/N-13 linked discorhabdin dimer that shared structural similarities with the 1-aminopentane-discorhabdin C adduct. To definitively assess the influence of the dienone moiety of discorhabdin C on cytotoxicity, a semi-synthetic hydrogenation derivative was prepared, affording a didebrominated ring-closed carbinolamine that was essentially devoid of tumour cell line cytotoxicity. Antiparasitic activity was assessed for a set of 14 discorhabdin alkaloids composed of natural products and semi-synthetic derivatives. Three compounds, (-)-discorhabdin L, a dimer of discorhabdin B and the discorhabdin C hydrogenation carbinolamine, exhibited pronounced activity towards Plasmodium falciparum K1 (IC50 30–90 nM) with acceptable to excellent selectivity (selectivity index 19–510) versus a non-malignant cell line. Full article
(This article belongs to the Special Issue Marine Natural Product of the South Pacific Area)
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Open AccessArticle
PHNQ from Evechinus chloroticus Sea Urchin Supplemented with Calcium Promotes Mineralization in Saos-2 Human Bone Cell Line
Mar. Drugs 2020, 18(7), 373; https://doi.org/10.3390/md18070373 - 19 Jul 2020
Viewed by 889
Abstract
Polyhydroxylated naphthoquinones (PHNQs), known as spinochromes that can be extracted from sea urchins, are bioactive compounds reported to have medicinal properties and antioxidant activity. The MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) cell viability assay showed that pure echinochrome A exhibited a cytotoxic effect on Saos-2 cells [...] Read more.
Polyhydroxylated naphthoquinones (PHNQs), known as spinochromes that can be extracted from sea urchins, are bioactive compounds reported to have medicinal properties and antioxidant activity. The MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) cell viability assay showed that pure echinochrome A exhibited a cytotoxic effect on Saos-2 cells in a dose-dependent manner within the test concentration range (15.625–65.5 µg/mL). The PHNQ extract from New Zealand sea urchin Evechinus chloroticus did not induce any cytotoxicity within the same concentration range after 21 days of incubation. Adding calcium chloride (CaCl2) with echinochrome A increased the number of viable cells, but when CaCl2 was added with the PHNQs, cell viability decreased. The effect of PHNQs extracted on mineralized nodule formation in Saos-2 cells was investigated using xylenol orange and von Kossa staining methods. Echinochrome A decreased the mineralized nodule formation significantly (p < 0.05), while nodule formation was not affected in the PHNQ treatment group. A significant (p < 0.05) increase in mineralization was observed in the presence of PHNQs (62.5 µg/mL) supplemented with 1.5 mM CaCl2. In conclusion, the results indicate that PHNQs have the potential to improve the formation of bone mineral phase in vitro, and future research in an animal model is warranted. Full article
(This article belongs to the Special Issue Marine Natural Product of the South Pacific Area)
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Open AccessArticle
Targeted Isolation of Rubrolides from the New Zealand Marine Tunicate Synoicum kuranui
Mar. Drugs 2020, 18(7), 337; https://doi.org/10.3390/md18070337 - 27 Jun 2020
Cited by 1 | Viewed by 970
Abstract
Global natural products social (GNPS) molecular networking is a useful tool to categorize chemical space within samples and streamline the discovery of new natural products. Here, we demonstrate its use in chemically profiling the extract of the marine tunicate Synoicum kuranui, comprised of [...] Read more.
Global natural products social (GNPS) molecular networking is a useful tool to categorize chemical space within samples and streamline the discovery of new natural products. Here, we demonstrate its use in chemically profiling the extract of the marine tunicate Synoicum kuranui, comprised of many previously reported rubrolides, for new chemical entities. Within the rubrolide cluster, two masses that did not correspond to previously reported congeners were detected, and, following MS-guided fractionation, led to the isolation of new methylated rubrolides T (3) and (Z/E)–U (4). Both compounds showed strong growth inhibitory activity against the Gram-positive bacteria Bacillus subtilis, with minimum inhibitory concentration (MIC) values of 0.41 and 0.91 μM, respectively. Full article
(This article belongs to the Special Issue Marine Natural Product of the South Pacific Area)
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Open AccessArticle
Quorum Sensing Inhibitory and Antifouling Activities of New Bromotyrosine Metabolites from the Polynesian Sponge Pseudoceratina n. sp.
Mar. Drugs 2020, 18(5), 272; https://doi.org/10.3390/md18050272 - 21 May 2020
Cited by 3 | Viewed by 1072
Abstract
Four new brominated tyrosine metabolites, aplyzanzines C–F (14), were isolated from the French Polynesian sponge Pseudoceratina n. sp., along with the two known 2-aminoimidazolic derivatives, purealidin A (5) and 6, previously isolated, respectively, from the sponges [...] Read more.
Four new brominated tyrosine metabolites, aplyzanzines C–F (14), were isolated from the French Polynesian sponge Pseudoceratina n. sp., along with the two known 2-aminoimidazolic derivatives, purealidin A (5) and 6, previously isolated, respectively, from the sponges Psammaplysilla purpurea and Verongula sp. Their structures were assigned based on the interpretation of their NMR and HRMS data. The compounds exhibited quorum sensing inhibition (QSi) and antifouling activities against several strains of bacteria and microalgae. To our knowledge, the QSi activity of this type of bromotyrosine metabolite is described here for the first time. Full article
(This article belongs to the Special Issue Marine Natural Product of the South Pacific Area)
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