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Special Issue "Bioactive Compounds from Marine Microbes"

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

Deadline for manuscript submissions: closed (30 November 2014)

Special Issue Editor

Guest Editor
Dr. Kirk R. Gustafson

Molecular Targets Laboratory, Center for Cancer Research, National Cancer Institute, Building 562, Room 201, Frederick, MD 21702-1201, USA
Website | E-Mail
Fax: +1 301 846 6157
Interests: natural products chemistry; chemical biology of natural products; NMR spectroscopy

Special Issue Information

Dear Colleagues,

The marine environment is a vast and largely unexplored resource for accessing diverse communities of microorganisms with novel biosynthetic capabilities. Marine habitats provide unique conditions for microbial growth and secondary metabolite expression that are not found in terrestrial ecosystems. The co-evolution of many marine macroorganisms, particularly invertebrate animals, with these microbes has often lead to the development of very close associations or symbiotic relationships between the host organism and a specific microbe. This in turn has resulted in the development and elaboration of unique microbial biosynthetic pathways and capabilities that can be utilized to generate novel compounds. Marine sediments are also now recognized as a rich source of microbial taxonomic diversity and new biologically active compounds. Efforts to cultivate and evaluate marine microorganisms and the associated compounds they can produce have expanded significantly in recent years, but this are of study is still very much in its infancy considering the vastness of the marine environment and the different types of microbial habitats found there.

Kirk R. Gustafson Ph. D.
Guest Editor

Keywords

  • actinomycetes
  • bacteria
  • biosynthesis
  • dereplication
  • fungi
  • metabolic modulators and elicitors
  • micro algae
  • quorum sensing
  • symbionts

Published Papers (24 papers)

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Research

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Open AccessArticle Bioactive Isopimarane Diterpenes from the Fungus, Epicoccum sp. HS-1, Associated with Apostichopus japonicus
Mar. Drugs 2015, 13(3), 1124-1132; doi:10.3390/md13031124
Received: 24 November 2014 / Revised: 8 February 2015 / Accepted: 13 February 2015 / Published: 2 March 2015
Cited by 4 | PDF Full-text (423 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
One new isopimarane diterpene (1), together with two known compounds, 11-deoxydiaporthein A (2) and iso-pimara-8(14),15-diene (3) were isolated from the culture of Epicoccum sp., which was associated with Apostichopus japonicus. Their structures were determined by the analysis
[...] Read more.
One new isopimarane diterpene (1), together with two known compounds, 11-deoxydiaporthein A (2) and iso-pimara-8(14),15-diene (3) were isolated from the culture of Epicoccum sp., which was associated with Apostichopus japonicus. Their structures were determined by the analysis of 1D and 2D NMR, as well as mass spectroscopic data. The absolute configuration of Compound 1 was deduced by a single-crystal X-ray diffraction experiment using CuKα radiation. In the bioactivity assay, both Compounds 1 and 2 exhibited α-glucosidase inhibitory activity with IC50 values of 4.6 ± 0.1 and 11.9 ± 0.4 μM, respectively. This was the first report on isopimarane diterpenes with α-glucosidase inhibitory activity. Full article
(This article belongs to the Special Issue Bioactive Compounds from Marine Microbes)
Open AccessArticle Biosynthesis of Akaeolide and Lorneic Acids and Annotation of Type I Polyketide Synthase Gene Clusters in the Genome of Streptomyces sp. NPS554
Mar. Drugs 2015, 13(1), 581-596; doi:10.3390/md13010581
Received: 3 December 2014 / Accepted: 9 January 2015 / Published: 16 January 2015
PDF Full-text (968 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The incorporation pattern of biosynthetic precursors into two structurally unique polyketides, akaeolide and lorneic acid A, was elucidated by feeding experiments with 13C-labeled precursors. In addition, the draft genome sequence of the producer, Streptomyces sp. NPS554, was performed and the biosynthetic gene
[...] Read more.
The incorporation pattern of biosynthetic precursors into two structurally unique polyketides, akaeolide and lorneic acid A, was elucidated by feeding experiments with 13C-labeled precursors. In addition, the draft genome sequence of the producer, Streptomyces sp. NPS554, was performed and the biosynthetic gene clusters for these polyketides were identified. The putative gene clusters contain all the polyketide synthase (PKS) domains necessary for assembly of the carbon skeletons. Combined with the 13C-labeling results, gene function prediction enabled us to propose biosynthetic pathways involving unusual carbon-carbon bond formation reactions. Genome analysis also indicated the presence of at least ten orphan type I PKS gene clusters that might be responsible for the production of new polyketides. Full article
(This article belongs to the Special Issue Bioactive Compounds from Marine Microbes)
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Open AccessArticle Asperlones A and B, Dinaphthalenone Derivatives from a Mangrove Endophytic Fungus Aspergillus sp. 16-5C
Mar. Drugs 2015, 13(1), 366-378; doi:10.3390/md13010366
Received: 26 November 2014 / Accepted: 23 December 2014 / Published: 13 January 2015
Cited by 6 | PDF Full-text (710 KB) | HTML Full-text | XML Full-text
Abstract
Racemic dinaphthalenone derivatives, (±)-asperlone A (1) and (±)-asperlone B (2), and two new azaphilones, 6′-hydroxy-(R)-mitorubrinic acid (3) and purpurquinone D (4), along with four known compounds, (−)-mitorubrinic acid (5), (−)-mitorubrin (
[...] Read more.
Racemic dinaphthalenone derivatives, (±)-asperlone A (1) and (±)-asperlone B (2), and two new azaphilones, 6′-hydroxy-(R)-mitorubrinic acid (3) and purpurquinone D (4), along with four known compounds, (−)-mitorubrinic acid (5), (−)-mitorubrin (6), purpurquinone A (7) and orsellinic acid (8), were isolated from the cultures of Aspergillus sp. 16-5C. The structures were elucidated using comprehensive spectroscopic methods, including 1D and 2D NMR spectra and the structures of 1 further confirmed by single-crystal X-ray diffraction analysis, while the absolute configuration of 3 and 4 were determined by comparing their optical rotation and CD with those of the literature, respectively. Compounds 1, 2 and 6 exhibited potent inhibitory effects against Mycobacterium tuberculosis protein tyrosine phosphatase B (MptpB) with IC50 values of 4.24 ± 0.41, 4.32 ± 0.60 and 3.99 ± 0.34 μM, respectively. Full article
(This article belongs to the Special Issue Bioactive Compounds from Marine Microbes)
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Open AccessArticle New Ikarugamycin Derivatives with Antifungal and Antibacterial Properties from Streptomyces zhaozhouensis
Mar. Drugs 2015, 13(1), 128-140; doi:10.3390/md13010128
Received: 13 November 2014 / Accepted: 16 December 2014 / Published: 29 December 2014
Cited by 7 | PDF Full-text (619 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A bioassay guided fractionation of the ethyl acetate extract from culture broths of the strain Streptomyces zhaozhouensis CA-185989 led to the isolation of three new polycyclic tetramic acid macrolactams (13) and four known compounds. All the new compounds were
[...] Read more.
A bioassay guided fractionation of the ethyl acetate extract from culture broths of the strain Streptomyces zhaozhouensis CA-185989 led to the isolation of three new polycyclic tetramic acid macrolactams (13) and four known compounds. All the new compounds were structurally related to the known Streptomyces metabolite ikarugamycin (4). Their structural elucidation was accomplished using a combination of electrospray-time of flight mass spectrometry (ESI-TOF MS) and 1D and 2D NMR analyses. Compounds 13 showed antifungal activity against Aspergillus fumigatus, Candida albicans and antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). Full article
(This article belongs to the Special Issue Bioactive Compounds from Marine Microbes)
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Open AccessArticle Chromomycin A2 Induces Autophagy in Melanoma Cells
Mar. Drugs 2014, 12(12), 5839-5855; doi:10.3390/md12125839
Received: 22 August 2014 / Revised: 17 November 2014 / Accepted: 20 November 2014 / Published: 4 December 2014
Cited by 2 | PDF Full-text (1041 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The present study highlights the biological effects of chromomycin A2 toward metastatic melanoma cells in culture. Besides chromomycin A2, chromomycin A3 and demethylchromomycin A2 were also identified from the extract derived from Streptomyces sp., recovered from Paracuru Beach, located in the northeast region
[...] Read more.
The present study highlights the biological effects of chromomycin A2 toward metastatic melanoma cells in culture. Besides chromomycin A2, chromomycin A3 and demethylchromomycin A2 were also identified from the extract derived from Streptomyces sp., recovered from Paracuru Beach, located in the northeast region of Brazil. The cytotoxic activity of chromomycin A2 was evaluated across a panel of human tumor cell lines, which found IC50 values in the nM-range for exposures of 48 and 72 h. MALME-3M, a metastatic melanoma cell line, showed the highest sensitivity to chromomycin A2 after 48h incubation, and was chosen as a model to investigate this potent cytotoxic effect. Treatment with chromomycin A2 at 30 nM reduced cell proliferation, but had no significant effect upon cell viability. Additionally, chromomycin A2 induced accumulation of cells in G0/G1 phase of the cell cycle, with consequent reduction of S and G2/M and unbalanced expression of cyclins. Chromomycin A2 treated cells depicted several cellular fragments resembling autophagosomes and increased expression of proteins LC3-A and LC3-B. Moreover, exposure to chromomycin A2 also induced the appearance of acidic vacuolar organelles in treated cells. These features combined are suggestive of the induction of autophagy promoted by chromomycin A2, a feature not previously described for chromomycins. Full article
(This article belongs to the Special Issue Bioactive Compounds from Marine Microbes)
Open AccessArticle Global and Phylogenetic Distribution of Quorum Sensing Signals, Acyl Homoserine Lactones, in the Family of Vibrionaceae
Mar. Drugs 2014, 12(11), 5527-5546; doi:10.3390/md12115527
Received: 1 September 2014 / Revised: 5 November 2014 / Accepted: 6 November 2014 / Published: 20 November 2014
Cited by 7 | PDF Full-text (1039 KB) | HTML Full-text | XML Full-text | Correction | Supplementary Files
Abstract
Bacterial quorum sensing (QS) and the corresponding signals, acyl homoserine lactones (AHLs), were first described for a luminescent Vibrio species. Since then, detailed knowledge has been gained on the functional level of QS; however, the abundance of AHLs in the family of Vibrionaceae
[...] Read more.
Bacterial quorum sensing (QS) and the corresponding signals, acyl homoserine lactones (AHLs), were first described for a luminescent Vibrio species. Since then, detailed knowledge has been gained on the functional level of QS; however, the abundance of AHLs in the family of Vibrionaceae in the environment has remained unclear. Three hundred and one Vibrionaceae strains were collected on a global research cruise and the prevalence and profile of AHL signals in this global collection were determined. AHLs were detected in 32 of the 301 strains using Agrobacterium tumefaciens and Chromobacterium violaceum reporter strains. Ethyl acetate extracts of the cultures were analysed by ultra-high performance liquid chromatography-high resolution mass spectrometry (MS) with automated tandem MS confirmation for AHLs. N-(3-hydroxy-hexanoyl) (OH-C6) and N-(3-hydroxy-decanoyl) (OH-C10) homoserine lactones were the most common AHLs found in 17 and 12 strains, respectively. Several strains produced a diversity of different AHLs, including N-heptanoyl (C7) HL. AHL-producing Vibrionaceae were found in polar, temperate and tropical waters. The AHL profiles correlated with strain phylogeny based on gene sequence homology, however not with geographical location. In conclusion, a wide range of AHL signals are produced by a number of clades in the Vibrionaceae family and these results will allow future investigations of inter- and intra-species interactions within this cosmopolitan family of marine bacteria. Full article
(This article belongs to the Special Issue Bioactive Compounds from Marine Microbes)
Open AccessArticle Sensitivity of Neurospora crassa to a Marine-Derived Aspergillus tubingensis Anhydride Exhibiting Antifungal Activity That Is Mediated by the MAS1 Protein
Mar. Drugs 2014, 12(9), 4713-4731; doi:10.3390/md12094713
Received: 23 July 2014 / Revised: 20 August 2014 / Accepted: 21 August 2014 / Published: 1 September 2014
Cited by 8 | PDF Full-text (2350 KB) | HTML Full-text | XML Full-text
Abstract
The fungus Aspergillus tubingensis (strain OY907) was isolated from the Mediterranean marine sponge Ircinia variabilis. Extracellular extracts produced by this strain were found to inhibit the growth of several fungi. Among the secreted extract components, a novel anhydride metabolite, tubingenoic anhydride A
[...] Read more.
The fungus Aspergillus tubingensis (strain OY907) was isolated from the Mediterranean marine sponge Ircinia variabilis. Extracellular extracts produced by this strain were found to inhibit the growth of several fungi. Among the secreted extract components, a novel anhydride metabolite, tubingenoic anhydride A (1) as well as the known 2-carboxymethyl-3-hexylmaleic acid anhydride, asperic acid, and campyrone A and C were purified and their structure elucidated. Compound 1 and 2-carboxymethyl-3-hexylmaleic acid anhydride inhibited Neurospora crassa growth (MIC = 330 and 207 μM, respectively) and affected hyphal morphology. We produced a N. crassa mutant exhibiting tolerance to 1 and found that a yet-uncharacterized gene, designated mas-1, whose product is a cytosolic protein, confers sensitivity to this compound. The ∆mas-1 strain showed increased tolerance to sublethal concentrations of the chitin synthase inhibitor polyoxin D, when compared to the wild type. In addition, the expression of chitin synthase genes was highly elevated in the ∆mas-1 strain, suggesting the gene product is involved in cell wall biosynthesis and the novel anhydride interferes with its function. Full article
(This article belongs to the Special Issue Bioactive Compounds from Marine Microbes)
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Open AccessArticle Eurothiocin A and B, Sulfur-Containing Benzofurans from a Soft Coral-Derived Fungus Eurotium rubrum SH-823
Mar. Drugs 2014, 12(6), 3669-3680; doi:10.3390/md12063669
Received: 30 April 2014 / Revised: 3 June 2014 / Accepted: 13 June 2014 / Published: 20 June 2014
Cited by 13 | PDF Full-text (864 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Two new sulfur-containing benzofuran derivatives, eurothiocin A and B (1 and 2), along with five known compounds, zinniol (3), butyrolactone I (4), aspernolide D (5), vermistatin (6), and methoxyvermistatin (7), were
[...] Read more.
Two new sulfur-containing benzofuran derivatives, eurothiocin A and B (1 and 2), along with five known compounds, zinniol (3), butyrolactone I (4), aspernolide D (5), vermistatin (6), and methoxyvermistatin (7), were isolated from the cultures of Eurotium rubrum SH-823, a fungus obtained from a Sarcophyton sp. soft coral collected from the South China Sea. The new compounds (1 and 2) share a methyl thiolester moiety, which is quite rare among natural secondary metabolites. The structures of these metabolites were assigned on the basis of detailed spectroscopic analysis. The absolute configurations of 1 and 2 were determined by comparison of the experimental and calculated electronic circular dichroism (ECD) data. Compounds 1 and 2 exhibited more potent inhibitory effects against α-glucosidase activity than the clinical α-glucosidase inhibitor acarbose. Further mechanistic analysis showed that both of them exhibited competitive inhibition characteristics. Full article
(This article belongs to the Special Issue Bioactive Compounds from Marine Microbes)
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Open AccessArticle Violapyrones H and I, New Cytotoxic Compounds Isolated from Streptomyces sp. Associated with the Marine Starfish Acanthaster planci
Mar. Drugs 2014, 12(6), 3283-3291; doi:10.3390/md12063283
Received: 18 March 2014 / Revised: 8 May 2014 / Accepted: 16 May 2014 / Published: 30 May 2014
Cited by 10 | PDF Full-text (614 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Two new α-pyrone derivatives, violapyrones H (1) and I (2), along with known violapyrones B (3) and C (4) were isolated from the fermentation broth of a marine actinomycete Streptomyces sp. The strain was derived
[...] Read more.
Two new α-pyrone derivatives, violapyrones H (1) and I (2), along with known violapyrones B (3) and C (4) were isolated from the fermentation broth of a marine actinomycete Streptomyces sp. The strain was derived from a crown-of-thorns starfish, Acanthaster planci, collected from Chuuk, Federated States of Micronesia. The structures of violapyrones were elucidated by the analysis of 1D and 2D NMR and HR-ESIMS data. Violapyrones (14) exhibited cytotoxicity against 10 human cancer cell lines with GI50 values of 1.10–26.12 μg/mL when tested using sulforhodamine B (SRB) assay. This is the first report on the cytotoxicity of violapyrones against cancer cell lines and the absolute configuration of violapyrone C. Full article
(This article belongs to the Special Issue Bioactive Compounds from Marine Microbes)
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Open AccessArticle Alterporriol-Type Dimers from the Mangrove Endophytic Fungus, Alternaria sp. (SK11), and Their MptpB Inhibitions
Mar. Drugs 2014, 12(5), 2953-2969; doi:10.3390/md12052953
Received: 20 March 2014 / Revised: 22 April 2014 / Accepted: 25 April 2014 / Published: 16 May 2014
Cited by 7 | PDF Full-text (769 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A new alterporriol-type anthranoid dimer, alterporriol S (1), along with seven known anthraquinone derivatives, (+)-aS-alterporriol C (2), hydroxybostrycin (3), halorosellinia A (4), tetrahydrobostrycin (5), 9α-hydroxydihydrodesoxybostrycin (6), austrocortinin (7
[...] Read more.
A new alterporriol-type anthranoid dimer, alterporriol S (1), along with seven known anthraquinone derivatives, (+)-aS-alterporriol C (2), hydroxybostrycin (3), halorosellinia A (4), tetrahydrobostrycin (5), 9α-hydroxydihydrodesoxybostrycin (6), austrocortinin (7) and 6-methylquinizarin (8), were isolated from the culture broth of the mangrove fungus, Alternaria sp. (SK11), from the South China Sea. Their structures and the relative configurations were elucidated using comprehensive spectroscopic methods, including 1D and 2D NMR spectra. The absolute configurations of 1 and the axial configuration of 2 were defined by experimental and theoretical ECD spectroscopy. 1 was identified as the first member of alterporriols consisting of a unique C-10−C-2′ linkage. Atropisomer 2 exhibited strong inhibitory activity against Mycobacterium tuberculosis protein tyrosine phosphatase B (MptpB) with an IC50 value 8.70 μM. Full article
(This article belongs to the Special Issue Bioactive Compounds from Marine Microbes)
Open AccessCommunication Oleic Acid Produced by a Marine Vibrio spp. Acts as an Anti-Vibrio parahaemolyticus Agent
Mar. Drugs 2011, 9(10), 2155-2163; doi:10.3390/md9102155
Received: 19 July 2011 / Revised: 13 August 2011 / Accepted: 23 August 2011 / Published: 24 October 2011
Cited by 4 | PDF Full-text (230 KB) | HTML Full-text | XML Full-text
Abstract
It is known that some strains of Vibrio parahaemolyticus are responsible for gastroenteric diseases caused by the ingestion of marine organisms contaminated with these bacterial strains. Organic products that show inhibitory activity on the growth of the pathogenic V. parahaemolyticus were extracted from
[...] Read more.
It is known that some strains of Vibrio parahaemolyticus are responsible for gastroenteric diseases caused by the ingestion of marine organisms contaminated with these bacterial strains. Organic products that show inhibitory activity on the growth of the pathogenic V. parahaemolyticus were extracted from a Vibrio native in the north of Chile. The inhibitory organic products were isolated by reverse phase chromatography and permeation by Sephadex LH20, and were characterized by spectroscopic and spectrometric techniques. The results showed that the prevailing active product is oleic acid, which was compared with standards by gas chromatography and high-performance liquid chromatography (HPLC). These active products might be useful for controlling the proliferation of pathogenic clones of V. parahaemolyticus. Full article
(This article belongs to the Special Issue Bioactive Compounds from Marine Microbes)
Open AccessArticle Identification of the Antibacterial Compound Produced by the Marine Epiphytic Bacterium Pseudovibrio sp. D323 and Related Sponge-Associated Bacteria
Mar. Drugs 2011, 9(8), 1391-1402; doi:10.3390/md9081391
Received: 10 July 2011 / Revised: 1 August 2011 / Accepted: 10 August 2011 / Published: 12 August 2011
Cited by 30 | PDF Full-text (1758 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Surface-associated marine bacteria often produce secondary metabolites with antagonistic activities. In this study, tropodithietic acid (TDA) was identified to be responsible for the antibacterial activity of the marine epiphytic bacterium Pseudovibrio sp. D323 and related strains. Phenol was also produced by these bacteria
[...] Read more.
Surface-associated marine bacteria often produce secondary metabolites with antagonistic activities. In this study, tropodithietic acid (TDA) was identified to be responsible for the antibacterial activity of the marine epiphytic bacterium Pseudovibrio sp. D323 and related strains. Phenol was also produced by these bacteria but was not directly related to the antibacterial activity. TDA was shown to effectively inhibit a range of marine bacteria from various phylogenetic groups. However TDA-producers themselves were resistant and are likely to possess resistance mechanism preventing autoinhibition. We propose that TDA in isolate D323 and related eukaryote-associated bacteria plays a role in defending the host organism against unwanted microbial colonisation and, possibly, bacterial pathogens. Full article
(This article belongs to the Special Issue Bioactive Compounds from Marine Microbes)
Open AccessArticle Evaluation of Marine Brown Algae and Sponges from Brazil as Anticoagulant and Antiplatelet Products
Mar. Drugs 2011, 9(8), 1346-1358; doi:10.3390/md9081346
Received: 25 June 2011 / Revised: 26 July 2011 / Accepted: 4 August 2011 / Published: 10 August 2011
Cited by 9 | PDF Full-text (138 KB) | HTML Full-text | XML Full-text
Abstract
The ischemic disorders, in which platelet aggregation and blood coagulation are involved, represent a major cause of disability and death worldwide. The antithrombotic therapy has unsatisfactory performance and may produce side effects. So, there is a need to seek molecules with antithrombotic properties.
[...] Read more.
The ischemic disorders, in which platelet aggregation and blood coagulation are involved, represent a major cause of disability and death worldwide. The antithrombotic therapy has unsatisfactory performance and may produce side effects. So, there is a need to seek molecules with antithrombotic properties. Marine organisms produce substances with different well defined ecological functions. Moreover, some of these molecules also exhibit pharmacological properties such as antiviral, anticancer, antiophidic and anticoagulant properties. The aim of this study was to evaluate, through in vitro tests, the effect of two extracts of brown algae and ten marine sponges from Brazil on platelet aggregation and blood coagulation. Our results revealed that most of the extracts were capable of inhibiting platelet aggregation and clotting measured by plasma recalcification tests, prothrombin time, activated partial thromboplastin time, and fibrinogenolytic activity. On the other hand, five of ten species of sponges induced platelet aggregation. Thus, the marine organisms studied here may have molecules with antithrombotic properties, presenting biotechnological potential to antithrombotic therapy. Further chemical investigation should be conducted on the active species to discover useful molecules for the development of new drugs to treat clotting disorders. Full article
(This article belongs to the Special Issue Bioactive Compounds from Marine Microbes)
Open AccessArticle Three Bianthraquinone Derivatives from the Mangrove Endophytic Fungus Alternaria sp. ZJ9-6B from the South China Sea
Mar. Drugs 2011, 9(5), 832-843; doi:10.3390/md9050832
Received: 28 March 2011 / Revised: 20 April 2011 / Accepted: 4 May 2011 / Published: 12 May 2011
Cited by 38 | PDF Full-text (332 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Three new bianthraquinone derivatives, alterporriol K (1), L (2) and M (3), along with six known compounds were obtained from extracts of the endophytic fungus Alternaria sp. ZJ9-6B, isolated from the mangrove Aegiceras corniculatum collected in the
[...] Read more.
Three new bianthraquinone derivatives, alterporriol K (1), L (2) and M (3), along with six known compounds were obtained from extracts of the endophytic fungus Alternaria sp. ZJ9-6B, isolated from the mangrove Aegiceras corniculatum collected in the South China Sea. Their structures were elucidated by one- and two-dimensional NMR spectroscopy, MS data analysis and circular dichroism measurements. Compounds 1, 2 and 3 were first isolated alterporriols with a C-2–C-2′ linkage. The crystallographic data of tetrahydroaltersolanol B (7) was reported for the first time. In the primary bioassays, alterporriol K and L exhibited moderate cytotoxic activity towards MDA-MB-435 and MCF-7 cells with IC50 values ranging from 13.1 to 29.1 µM. Full article
(This article belongs to the Special Issue Bioactive Compounds from Marine Microbes)
Open AccessArticle 3-O-Methylfunicone, a Selective Inhibitor of Mammalian Y-Family DNA Polymerases from an Australian Sea Salt Fungal Strain
Mar. Drugs 2009, 7(4), 624-639; doi:10.3390/md7040624
Received: 12 October 2009 / Revised: 18 November 2009 / Accepted: 19 November 2009 / Published: 23 November 2009
Cited by 23 | PDF Full-text (279 KB) | HTML Full-text | XML Full-text
Abstract
We isolated a pol inhibitor from the cultured mycelia extract of a fungal strain isolated from natural salt from a sea salt pan in Australia, which was identified as 3-O-methylfunicone by spectroscopic analyses. This compound selectively inhibited the activities of mammalian Y-family DNA
[...] Read more.
We isolated a pol inhibitor from the cultured mycelia extract of a fungal strain isolated from natural salt from a sea salt pan in Australia, which was identified as 3-O-methylfunicone by spectroscopic analyses. This compound selectively inhibited the activities of mammalian Y-family DNA polymerases (pols) (i.e., pols η, ι and κ). Among these pols, human pol κ activity was most strongly inhibited, with an IC50 value of 12.5 μM. On the other hand, the compound barely influenced the activities of the other families of mammalian pols, such as A-family (i.e., pol γ), B-family (i.e., pols α, δ and ε) or X-family (i.e., pols β, λ and terminal deoxynucleotidyl transferase), and showed no effect on the activities of fish pol δ, plant pols, prokaryotic pols and other DNA metabolic enzymes, such as calf primase of pol α, human immunodeficiency virus type-1 (HIV-1) reverse transcriptase, human telomerase, T7 RNA polymerase, mouse IMP dehydrogenase (type II), human topoisomerases I and II, T4 polynucleotide kinase or bovine deoxyribonuclease I. This compound also suppressed the growth of two cultured human cancer cell lines, HCT116 (colon carcinoma cells) and HeLa (cervix carcinoma cells), and UV-treated HeLa cells exhibited lower clonogenic survival in the presence of inhibitor. Full article
(This article belongs to the Special Issue Bioactive Compounds from Marine Microbes)
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Open AccessArticle Preliminary Characterization of Extracellular Allelochemicals of the Toxic Marine Dinoflagellate Alexandrium tamarense Using a Rhodomonas salina Bioassay
Mar. Drugs 2009, 7(4), 497-522; doi:10.3390/md7040497
Received: 18 September 2009 / Revised: 28 October 2009 / Accepted: 29 October 2009 / Published: 2 November 2009
Cited by 41 | PDF Full-text (249 KB) | HTML Full-text | XML Full-text
Abstract
Members of the marine dinoflagellate genus Alexandrium are known to exude allelochemicals, unrelated to well-known neurotoxins (PSP-toxins, spirolides), with negative effects on other phytoplankton and marine grazers. Physico/chemical characterization of extracellular lytic compounds of A. tamarense, quantified by Rhodomonas salina bioassay, showed
[...] Read more.
Members of the marine dinoflagellate genus Alexandrium are known to exude allelochemicals, unrelated to well-known neurotoxins (PSP-toxins, spirolides), with negative effects on other phytoplankton and marine grazers. Physico/chemical characterization of extracellular lytic compounds of A. tamarense, quantified by Rhodomonas salina bioassay, showed that the lytic activity, and hence presumably the compounds were stable over wide ranges of temperatures and pH and were refractory to bacterial degradation. Two distinct lytic fractions were collected by reversed-phase solid-phase extraction. The more hydrophilic fraction accounted for about 2% of the whole lytic activity of the A. tamarense culture supernatant, while the less hydrophilic one accounted for about 98% of activity. Although temporal stability of the compounds is high, substantial losses were evident during purification. Lytic activity was best removed from aqueous phase with chloroform-methanol (3:1). A “pseudo-loss” of lytic activity in undisturbed and low-concentrated samples and high activity of an emulsion between aqueous and n-hexane phase after liquid-liquid partition are strong evidence for the presence of amphipathic compounds. Lytic activity in the early fraction of gel permeation chromatography and lack of activity after 5 kD ultrafiltration indicate that the lytic agents form large aggregates or macromolecular complexes. Full article
(This article belongs to the Special Issue Bioactive Compounds from Marine Microbes)
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Review

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Open AccessReview Marine Extremophiles: A Source of Hydrolases for Biotechnological Applications
Mar. Drugs 2015, 13(4), 1925-1965; doi:10.3390/md13041925
Received: 1 December 2014 / Revised: 22 March 2015 / Accepted: 25 March 2015 / Published: 3 April 2015
Cited by 19 | PDF Full-text (1197 KB) | HTML Full-text | XML Full-text
Abstract
The marine environment covers almost three quarters of the planet and is where evolution took its first steps. Extremophile microorganisms are found in several extreme marine environments, such as hydrothermal vents, hot springs, salty lakes and deep-sea floors. The ability of these microorganisms
[...] Read more.
The marine environment covers almost three quarters of the planet and is where evolution took its first steps. Extremophile microorganisms are found in several extreme marine environments, such as hydrothermal vents, hot springs, salty lakes and deep-sea floors. The ability of these microorganisms to support extremes of temperature, salinity and pressure demonstrates their great potential for biotechnological processes. Hydrolases including amylases, cellulases, peptidases and lipases from hyperthermophiles, psychrophiles, halophiles and piezophiles have been investigated for these reasons. Extremozymes are adapted to work in harsh physical-chemical conditions and their use in various industrial applications such as the biofuel, pharmaceutical, fine chemicals and food industries has increased. The understanding of the specific factors that confer the ability to withstand extreme habitats on such enzymes has become a priority for their biotechnological use. The most studied marine extremophiles are prokaryotes and in this review, we present the most studied archaea and bacteria extremophiles and their hydrolases, and discuss their use for industrial applications. Full article
(This article belongs to the Special Issue Bioactive Compounds from Marine Microbes)
Open AccessReview Marine Pseudovibrio sp. as a Novel Source of Antimicrobials
Mar. Drugs 2014, 12(12), 5916-5929; doi:10.3390/md12125916
Received: 25 August 2014 / Revised: 24 November 2014 / Accepted: 25 November 2014 / Published: 9 December 2014
Cited by 2 | PDF Full-text (565 KB) | HTML Full-text | XML Full-text
Abstract
Antibiotic resistance among pathogenic microorganisms is becoming ever more common. Unfortunately, the development of new antibiotics which may combat resistance has decreased. Recently, however the oceans and the marine animals that reside there have received increased attention as a potential source for natural
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Antibiotic resistance among pathogenic microorganisms is becoming ever more common. Unfortunately, the development of new antibiotics which may combat resistance has decreased. Recently, however the oceans and the marine animals that reside there have received increased attention as a potential source for natural product discovery. Many marine eukaryotes interact and form close associations with microorganisms that inhabit their surfaces, many of which can inhibit the attachment, growth or survival of competitor species. It is the bioactive compounds responsible for the inhibition that is of interest to researchers on the hunt for novel bioactives. The genus Pseudovibrio has been repeatedly identified from the bacterial communities isolated from marine surfaces. In addition, antimicrobial activity assays have demonstrated significant antimicrobial producing capabilities throughout the genus. This review will describe the potency, spectrum and possible novelty of the compounds produced by these bacteria, while highlighting the capacity for this genus to produce natural antimicrobial compounds which could be employed to control undesirable bacteria in the healthcare and food production sectors. Full article
(This article belongs to the Special Issue Bioactive Compounds from Marine Microbes)
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Open AccessReview Microbial Communities and Bioactive Compounds in Marine Sponges of the Family Irciniidae—A Review
Mar. Drugs 2014, 12(10), 5089-5122; doi:10.3390/md12105089
Received: 21 August 2014 / Revised: 12 September 2014 / Accepted: 16 September 2014 / Published: 30 September 2014
Cited by 5 | PDF Full-text (685 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Marine sponges harbour complex microbial communities of ecological and biotechnological importance. Here, we propose the application of the widespread sponge family Irciniidae as an appropriate model in microbiology and biochemistry research. Half a gram of one Irciniidae specimen hosts hundreds of bacterial species—the
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Marine sponges harbour complex microbial communities of ecological and biotechnological importance. Here, we propose the application of the widespread sponge family Irciniidae as an appropriate model in microbiology and biochemistry research. Half a gram of one Irciniidae specimen hosts hundreds of bacterial species—the vast majority of which are difficult to cultivate—and dozens of fungal and archaeal species. The structure of these symbiont assemblages is shaped by the sponge host and is highly stable over space and time. Two types of quorum-sensing molecules have been detected in these animals, hinting at microbe-microbe and host-microbe signalling being important processes governing the dynamics of the Irciniidae holobiont. Irciniids are vulnerable to disease outbreaks, and concerns have emerged about their conservation in a changing climate. They are nevertheless amenable to mariculture and laboratory maintenance, being attractive targets for metabolite harvesting and experimental biology endeavours. Several bioactive terpenoids and polyketides have been retrieved from Irciniidae sponges, but the actual producer (host or symbiont) of these compounds has rarely been clarified. To tackle this, and further pertinent questions concerning the functioning, resilience and physiology of these organisms, truly multi-layered approaches integrating cutting-edge microbiology, biochemistry, genetics and zoology research are needed. Full article
(This article belongs to the Special Issue Bioactive Compounds from Marine Microbes)
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Open AccessReview Production of Bioactive Secondary Metabolites by Marine Vibrionaceae
Mar. Drugs 2011, 9(9), 1440-1468; doi:10.3390/md9091440
Received: 28 July 2011 / Revised: 11 August 2011 / Accepted: 15 August 2011 / Published: 25 August 2011
Cited by 41 | PDF Full-text (1137 KB) | HTML Full-text | XML Full-text
Abstract
Bacteria belonging to the Vibrionaceae family are widespread in the marine environment. Today, 128 species of vibrios are known. Several of them are infamous for their pathogenicity or symbiotic relationships. Despite their ability to interact with eukaryotes, the vibrios are greatly underexplored for
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Bacteria belonging to the Vibrionaceae family are widespread in the marine environment. Today, 128 species of vibrios are known. Several of them are infamous for their pathogenicity or symbiotic relationships. Despite their ability to interact with eukaryotes, the vibrios are greatly underexplored for their ability to produce bioactive secondary metabolites and studies have been limited to only a few species. Most of the compounds isolated from vibrios so far are non-ribosomal peptides or hybrids thereof, with examples of N-containing compounds produced independent of nonribosomal peptide synthetases (NRPS). Though covering a limited chemical space, vibrios produce compounds with attractive biological activities, including antibacterial, anticancer, and antivirulence activities. This review highlights some of the most interesting structures from this group of bacteria. Many compounds found in vibrios have also been isolated from other distantly related bacteria. This cosmopolitan occurrence of metabolites indicates a high incidence of horizontal gene transfer, which raises interesting questions concerning the ecological function of some of these molecules. This account underlines the pending potential for exploring new bacterial sources of bioactive compounds and the challenges related to their investigation. Full article
(This article belongs to the Special Issue Bioactive Compounds from Marine Microbes)
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Open AccessReview Bacteriocin as Weapons in the Marine Animal-Associated Bacteria Warfare: Inventory and Potential Applications as an Aquaculture Probiotic
Mar. Drugs 2010, 8(4), 1153-1177; doi:10.3390/md8041153
Received: 6 February 2010 / Revised: 28 March 2010 / Accepted: 1 April 2010 / Published: 4 April 2010
Cited by 47 | PDF Full-text (954 KB) | HTML Full-text | XML Full-text
Abstract
As the association of marine animals with bacteria has become more commonly recognized, researchers have increasingly questioned whether these animals actually produce many of the bioactive compounds originally isolated from them. Bacteriocins, ribosomally synthesized antibiotic peptides, constitute one of the most potent weapons
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As the association of marine animals with bacteria has become more commonly recognized, researchers have increasingly questioned whether these animals actually produce many of the bioactive compounds originally isolated from them. Bacteriocins, ribosomally synthesized antibiotic peptides, constitute one of the most potent weapons to fight against pathogen infections. Indeed, bacteriocinogenic bacteria may prevent pathogen dissemination by occupying the same ecological niche. Bacteriocinogenic strains associated with marine animals are a relevant source for isolation of probiotics. This review draws up an inventory of the marine bacteriocinogenic strains isolated from animal-associated microbial communities, known to date. Bacteriocin-like inhibitory substances (BLIS) and fully-characterized bacteriocins are described. Finally, their applications as probiotics in aquaculture are discussed. Full article
(This article belongs to the Special Issue Bioactive Compounds from Marine Microbes)
Open AccessReview Production of Metabolites as Bacterial Responses to the Marine Environment
Mar. Drugs 2010, 8(3), 705-727; doi:10.3390/md8030705
Received: 28 January 2010 / Revised: 26 February 2010 / Accepted: 16 March 2010 / Published: 17 March 2010
Cited by 47 | PDF Full-text (196 KB) | HTML Full-text | XML Full-text
Abstract
Bacteria in marine environments are often under extreme conditions of e.g., pressure, temperature, salinity, and depletion of micronutrients, with survival and proliferation often depending on the ability to produce biologically active compounds. Some marine bacteria produce biosurfactants, which help to transport hydrophobic low
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Bacteria in marine environments are often under extreme conditions of e.g., pressure, temperature, salinity, and depletion of micronutrients, with survival and proliferation often depending on the ability to produce biologically active compounds. Some marine bacteria produce biosurfactants, which help to transport hydrophobic low water soluble substrates by increasing their bioavailability. However, other functions related to heavy metal binding, quorum sensing and biofilm formation have been described. In the case of metal ions, bacteria developed a strategy involving the release of binding agents to increase their bioavailability. In the particular case of the Fe3+ ion, which is almost insoluble in water, bacteria secrete siderophores that form soluble complexes with the ion, allowing the cells to uptake the iron required for cell functioning. Adaptive changes in the lipid composition of marine bacteria have been observed in response to environmental variations in pressure, temperature and salinity. Some fatty acids, including docosahexaenoic and eicosapentaenoic acids, have only been reported in prokaryotes in deep-sea bacteria. Cell membrane permeability can also be adapted to extreme environmental conditions by the production of hopanoids, which are pentacyclic triterpenoids that have a function similar to cholesterol in eukaryotes. Bacteria can also produce molecules that prevent the attachment, growth and/or survival of challenging organisms in competitive environments. The production of these compounds is particularly important in surface attached strains and in those in biofilms. The wide array of compounds produced by marine bacteria as an adaptive response to demanding conditions makes them suitable candidates for screening of compounds with commercially interesting biological functions. Biosurfactants produced by marine bacteria may be helpful to increase mass transfer in different industrial processes and in the bioremediation of hydrocarbon-contaminated sites. Siderophores are necessary e.g., in the treatment of diseases with metal ion imbalance, while antifouling compounds could be used to treat man-made surfaces that are used in marine environments. New classes of antibiotics could efficiently combat bacteria resistant to the existing antibiotics. The present work aims to provide a comprehensive review of the metabolites produced by marine bacteria in order to cope with intrusive environments, and to illustrate how such metabolites can be advantageously used in several relevant areas, from bioremediation to health and pharmaceutical sectors. Full article
(This article belongs to the Special Issue Bioactive Compounds from Marine Microbes)
Open AccessReview Development of Novel Drugs from Marine Surface Associated Microorganisms
Mar. Drugs 2010, 8(3), 438-459; doi:10.3390/md8030438
Received: 18 January 2010 / Revised: 3 February 2010 / Accepted: 22 February 2010 / Published: 1 March 2010
Cited by 97 | PDF Full-text (172 KB) | HTML Full-text | XML Full-text
Abstract
While the oceans cover more than 70% of the Earth’s surface, marine derived microbial natural products have been largely unexplored. The marine environment is a habitat for many unique microorganisms, which produce biologically active compounds (“bioactives”) to adapt to particular environmental conditions. For
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While the oceans cover more than 70% of the Earth’s surface, marine derived microbial natural products have been largely unexplored. The marine environment is a habitat for many unique microorganisms, which produce biologically active compounds (“bioactives”) to adapt to particular environmental conditions. For example, marine surface associated microorganisms have proven to be a rich source for novel bioactives because of the necessity to evolve allelochemicals capable of protecting the producer from the fierce competition that exists between microorganisms on the surfaces of marine eukaryotes. Chemically driven interactions are also important for the establishment of cross-relationships between microbes and their eukaryotic hosts, in which organisms producing antimicrobial compounds (“antimicrobials”), may protect the host surface against over colonisation in return for a nutrient rich environment. As is the case for bioactive discovery in general, progress in the detection and characterization of marine microbial bioactives has been limited by a number of obstacles, such as unsuitable culture conditions, laborious purification processes, and a lack of de-replication. However many of these limitations are now being overcome due to improved microbial cultivation techniques, microbial (meta-) genomic analysis and novel sensitive analytical tools for structural elucidation. Here we discuss how these technical advances, together with a better understanding of microbial and chemical ecology, will inevitably translate into an increase in the discovery and development of novel drugs from marine microbial sources in the future. Full article
(This article belongs to the Special Issue Bioactive Compounds from Marine Microbes)

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Open AccessCorrection Correction: Rasmussen, B.B., et al. Global and Phylogenetic Distribution of Quorum Sensing Signals, Acyl Homoserine Lactones, in the Family of Vibrionaceae. Mar. Drugs 2014, 12, 5527–5546
Mar. Drugs 2015, 13(3), 1548-1551; doi:10.3390/md13031548
Received: 16 February 2015 / Accepted: 17 February 2015 / Published: 20 March 2015
PDF Full-text (353 KB) | HTML Full-text | XML Full-text
Abstract The authors wish to make the following corrections to this paper [1]: Due to duplicated and missing data in Table 3, Page 5533, replace: [...] Full article
(This article belongs to the Special Issue Bioactive Compounds from Marine Microbes)

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