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Special Issue "Advances in Marine Natural Product Characterisation and Separation Methodologies"

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

Deadline for manuscript submissions: 30 November 2018

Special Issue Editor

Guest Editor
Dr. Sylvia Urban

School of Applied Sciences (Applied Chemistry), RMIT University (City Campus), GPO Box 2476V, Melbourne 3001, Victoria, Australia
Website | E-Mail
Phone: +61 3 9925 3376
Fax: +61 3 9925 3747
Interests: marine and terrestrial natural products chemistry; isolation and structural characterization; NMR spectroscopy; analytical separation methodologies

Special Issue Information

Dear Colleagues,

The search for bioactive marine natural products calls upon the need for efficient chemical profiling strategies together with the need to make advances in separation and characterization methodologies in order to expedite their discovery. This Special Issue of Marine Drugs aims to highlight advances in extraction, isolation, purification and dereplication methodologies in the quest for bioactive marine natural products.

Dr. Sylvia Urban
Guest Editor

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 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

  • Natural Products
  • Drug Discovery
  • Chemical Profiling
  • Spectroscopy
  • Chromatgraphy

Published Papers (6 papers)

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Research

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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Abstract
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
[...] Read more.
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 Absolute Configuration Determination of Retroflexanone Using the Advanced Mosher Method and Application of HPLC-NMR
Mar. Drugs 2018, 16(6), 205; https://doi.org/10.3390/md16060205
Received: 23 May 2018 / Revised: 6 June 2018 / Accepted: 7 June 2018 / Published: 12 June 2018
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Abstract
The absolute configuration of retroflexanone (1) and a closely related phlorogluinol (2) was established using the advanced Mosher method and by application of HPLC-NMR. HPLC-NMR permitted a small scale Mosher method analysis to be carried out on these unstable phloroglucinols. Full article
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Open AccessArticle Optimum Production Conditions, Purification, Identification, and Antioxidant Activity of Violaxanthin from Microalga Eustigmatos cf. polyphem (Eustigmatophyceae)
Mar. Drugs 2018, 16(6), 190; https://doi.org/10.3390/md16060190
Received: 16 May 2018 / Revised: 24 May 2018 / Accepted: 30 May 2018 / Published: 1 June 2018
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Abstract
Violaxanthin is a major xanthophyll pigment in the microalga Eustigmatos cf. polyphem, but the amount produced after propagation can vary depending upon culture conditions. In this study, the effects of cultivation time, nitrogen concentration, light intensity, and culture mode on violaxanthin production
[...] Read more.
Violaxanthin is a major xanthophyll pigment in the microalga Eustigmatos cf. polyphem, but the amount produced after propagation can vary depending upon culture conditions. In this study, the effects of cultivation time, nitrogen concentration, light intensity, and culture mode on violaxanthin production were investigated. The results showed that this microalga vigorously grew and maintained a high level of violaxanthin in the fed-batch culture, and the highest violaxanthin productivity of 1.10 ± 0.03 mg L−1 d−1 was obtained under low light illumination with 18 mM of initial nitrogen supply for ten days. Additionally, violaxanthin was purified from E. cf. polyphem by silica gel chromatography and preparative high-performance liquid chromatography (PHPLC), and identified with high-resolution mass spectrometry (HRMS). The antioxidant activity of the purified violaxanthin was evaluated by three tests in vitro: reducing power assay, 2,2-diphenyl-1-picrylhydrazyl (DPPH), and 2,2-azobis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) radical assays. The strongest inhibition of purified violaxanthin occurred during the scavenging of ABTS+ radicals, with EC50 of 15.25 μg mL−1. In conclusion, this is the first report to investigate the effects of different culture conditions on violaxanthin accumulation in E. cf. polyphem and provide a novel source for the production of violaxanthin that can be used for food and pharmaceutical applications. Full article
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Open AccessArticle Preparative Separation and Purification of Trichothecene Mycotoxins from the Marine Fungus Fusarium sp. LS68 by High-Speed Countercurrent Chromatography in Stepwise Elution Mode
Mar. Drugs 2018, 16(2), 73; https://doi.org/10.3390/md16020073
Received: 16 January 2018 / Revised: 12 February 2018 / Accepted: 16 February 2018 / Published: 24 February 2018
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Abstract
The contamination of foods and animal feeds with trichothecene mycotoxins is a growing concern for human and animal health. As such, large quantities of pure trichothecene mycotoxins are necessary for food safety monitoring and toxicological research. A new and effective method for the
[...] Read more.
The contamination of foods and animal feeds with trichothecene mycotoxins is a growing concern for human and animal health. As such, large quantities of pure trichothecene mycotoxins are necessary for food safety monitoring and toxicological research. A new and effective method for the purification of trichothecene mycotoxins from a marine fungus, Fusarium sp. LS68, is described herein. Preparative high-speed countercurrent chromatography (HSCCC) was utilized for the scalable isolation and purification of four trichothecene mycotoxins for the first time in stepwise elution mode, with a biphasic solvent system composed of hexanes–EtOAc–CH3OH–H2O (6:4:5:5, v/v/v/v) and (8.5:1.5:5:5,v/v/v/v). This preparative HSCCC separation was performed on 200 mg of crude sample to yield four trichothecene mycotoxins, roridin E (1), roridin E acetate (2), verrucarin L acetate (3), and verrucarin J (4) in a single run, with each of >98% purity. These compounds were identified by MS, 1H NMR, 13C NMR, and polarimetry. The results demonstrate an efficient HSCCC method for the separation of trichothecene mycotoxins, which can be utilized to produce pure commercial and research standards. Full article
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Open AccessArticle A Dereplication and Bioguided Discovery Approach to Reveal New Compounds from a Marine-Derived Fungus Stilbella fimetaria
Mar. Drugs 2017, 15(8), 253; https://doi.org/10.3390/md15080253
Received: 4 July 2017 / Revised: 27 July 2017 / Accepted: 31 July 2017 / Published: 13 August 2017
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Abstract
A marine-derived Stilbella fimetaria fungal strain was screened for new bioactive compounds based on two different approaches: (i) bio-guided approach using cytotoxicity and antimicrobial bioassays; and (ii) dereplication based approach using liquid chromatography with both diode array detection and high resolution mass spectrometry.
[...] Read more.
A marine-derived Stilbella fimetaria fungal strain was screened for new bioactive compounds based on two different approaches: (i) bio-guided approach using cytotoxicity and antimicrobial bioassays; and (ii) dereplication based approach using liquid chromatography with both diode array detection and high resolution mass spectrometry. This led to the discovery of several bioactive compound families with different biosynthetic origins, including pimarane-type diterpenoids and hybrid polyketide-non ribosomal peptide derived compounds. Prefractionation before bioassay screening proved to be a great aid in the dereplication process, since separate fractions displaying different bioactivities allowed a quick tentative identification of known antimicrobial compounds and of potential new analogues. A new pimarane-type diterpene, myrocin F, was discovered in trace amounts and displayed cytotoxicity towards various cancer cell lines. Further media optimization led to increased production followed by the purification and bioactivity screening of several new and known pimarane-type diterpenoids. A known broad-spectrum antifungal compound, ilicicolin H, was purified along with two new analogues, hydroxyl-ilicicolin H and ilicicolin I, and their antifungal activity was evaluated. Full article
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Open AccessArticle Isolation and Tissue Distribution of an Insulin-Like Androgenic Gland Hormone (IAG) of the Male Red Deep-Sea Crab, Chaceon quinquedens
Mar. Drugs 2017, 15(8), 241; https://doi.org/10.3390/md15080241
Received: 14 July 2017 / Revised: 27 July 2017 / Accepted: 29 July 2017 / Published: 1 August 2017
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Abstract
The insulin-like androgenic gland hormone (IAG) found in decapod crustaceans is known to regulate sexual development in males. IAG is produced in the male-specific endocrine tissue, the androgenic gland (AG); however, IAG expression has been also observed in other tissues of decapod crustacean
[...] Read more.
The insulin-like androgenic gland hormone (IAG) found in decapod crustaceans is known to regulate sexual development in males. IAG is produced in the male-specific endocrine tissue, the androgenic gland (AG); however, IAG expression has been also observed in other tissues of decapod crustacean species including Callinectes sapidus and Scylla paramamosain. This study aimed to isolate the full-length cDNA sequence of IAG from the AG of male red deep-sea crabs, Chaceon quinquedens (ChqIAG), and to examine its tissue distribution. To this end, we employed polymerase chain reaction cloning with degenerate primers and 5′ and 3′ rapid amplification of cDNA ends (RACE). The full-length ChqIAG cDNA sequence (1555 nt) includes a 366 nt 5′ untranslated region a 453 nt open reading frame encoding 151 amino acids, and a relatively long 3′ UTR of 733 nt. The ORF consists of a 19 aa signal peptide, 32 aa B chain, 56 aa C chain, and 44 aa A chain. The putative ChqIAG amino acid sequence is most similar to those found in other crab species, including C. sapidus and S. paramamosain, which are clustered together phylogenetically. Full article
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