Marine Drugs

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Open AccessCommunication

Oleic Acid Produced by a Marine Vibrio spp. Acts as an Anti-Vibrio parahaemolyticus Agent

by Yanett Leyton, Jorge Borquez, José Darias, Mercedes Cueto, Ana R. Díaz-Marrero and Carlos Riquelme

Mar. Drugs 2011, 9(10), 2155-2163; https://doi.org/10.3390/md9102155 - 24 Oct 2011

Cited by 15 | Viewed by 7324

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)

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Open AccessReview

Kinase Inhibitors from Marine Sponges

by Danielle Skropeta, Natalie Pastro and Ana Zivanovic

Mar. Drugs 2011, 9(10), 2131-2154; https://doi.org/10.3390/md9102131 - 24 Oct 2011

Cited by 67 | Viewed by 9734

Abstract

Protein kinases play a critical role in cell regulation and their deregulation is a contributing factor in an increasing list of diseases including cancer. Marine sponges have yielded over 70 novel compounds to date that exhibit significant inhibitory activity towards a range of [...] Read more.

Protein kinases play a critical role in cell regulation and their deregulation is a contributing factor in an increasing list of diseases including cancer. Marine sponges have yielded over 70 novel compounds to date that exhibit significant inhibitory activity towards a range of protein kinases. These compounds, which belong to diverse structural classes, are reviewed herein, and ordered based upon the kinase that they inhibit. Relevant synthetic studies on the marine natural product kinase inhibitors have also been included. Full article

(This article belongs to the Special Issue Bioactive Compound from Marine Sponges)

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Graphical abstract

472 KiB

Open AccessReview

Important Determinants for Fucoidan Bioactivity: A Critical Review of Structure-Function Relations and Extraction Methods for Fucose-Containing Sulfated Polysaccharides from Brown Seaweeds

by Marcel Tutor Ale, Jørn D. Mikkelsen and Anne S. Meyer

Mar. Drugs 2011, 9(10), 2106-2130; https://doi.org/10.3390/md9102106 - 24 Oct 2011

Cited by 564 | Viewed by 30089

Abstract

Seaweeds—or marine macroalgae—notably brown seaweeds in the class Phaeophyceae, contain fucoidan. Fucoidan designates a group of certain fucose-containing sulfated polysaccharides (FCSPs) that have a backbone built of (1→3)-linked α-l-fucopyranosyl or of alternating (1→3)- and (1→4)-linked α-l-fucopyranosyl residues, but also include sulfated galactofucans with [...] Read more.

Seaweeds—or marine macroalgae—notably brown seaweeds in the class Phaeophyceae, contain fucoidan. Fucoidan designates a group of certain fucose-containing sulfated polysaccharides (FCSPs) that have a backbone built of (1→3)-linked α-l-fucopyranosyl or of alternating (1→3)- and (1→4)-linked α-l-fucopyranosyl residues, but also include sulfated galactofucans with backbones built of (1→6)-β-d-galacto- and/or (1→2)-β-d-mannopyranosyl units with fucose or fuco-oligosaccharide branching, and/or glucuronic acid, xylose or glucose substitutions. These FCSPs offer several potentially beneficial bioactive functions for humans. The bioactive properties may vary depending on the source of seaweed, the compositional and structural traits, the content (charge density), distribution, and bonding of the sulfate substitutions, and the purity of the FCSP product. The preservation of the structural integrity of the FCSP molecules essentially depends on the extraction methodology which has a crucial, but partly overlooked, significance for obtaining the relevant structural features required for specific biological activities and for elucidating structure-function relations. The aim of this review is to provide information on the most recent developments in the chemistry of fucoidan/FCSPs emphasizing the significance of different extraction techniques for the structural composition and biological activity with particular focus on sulfate groups. Full article

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Open AccessArticle

Antibacterial Activity of Marine and Black Band Disease Cyanobacteria against Coral-Associated Bacteria

by Miroslav Gantar, Longin T. Kaczmarsky, Dina Stanić, Aaron W. Miller and Laurie L. Richardson

Mar. Drugs 2011, 9(10), 2089-2105; https://doi.org/10.3390/md9102089 - 24 Oct 2011

Cited by 30 | Viewed by 8926

Abstract

Black band disease (BBD) of corals is a cyanobacteria-dominated polymicrobial disease that contains diverse populations of heterotrophic bacteria. It is one of the most destructive of coral diseases and is found globally on tropical and sub-tropical reefs. We assessed ten strains of BBD [...] Read more.

Black band disease (BBD) of corals is a cyanobacteria-dominated polymicrobial disease that contains diverse populations of heterotrophic bacteria. It is one of the most destructive of coral diseases and is found globally on tropical and sub-tropical reefs. We assessed ten strains of BBD cyanobacteria, and ten strains of cyanobacteria isolated from other marine sources, for their antibacterial effect on growth of heterotrophic bacteria isolated from BBD, from the surface mucopolysaccharide layer (SML) of healthy corals, and three known bacterial coral pathogens. Assays were conducted using two methods: co-cultivation of cyanobacterial and bacterial isolates, and exposure of test bacteria to (hydrophilic and lipophilic) cyanobacterial cell extracts. During co-cultivation, 15 of the 20 cyanobacterial strains tested had antibacterial activity against at least one of the test bacterial strains. Inhibition was significantly higher for BBD cyanobacteria when compared to other marine cyanobacteria. Lipophilic extracts were more active than co-cultivation (extracts of 18 of the 20 strains were active) while hydrophilic extracts had very limited activity. In some cases co-cultivation resulted in stimulation of BBD and SML bacterial growth. Our results suggest that BBD cyanobacteria are involved in structuring the complex polymicrobial BBD microbial community by production of antimicrobial compounds. Full article

(This article belongs to the Special Issue Algal Toxins)

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Open AccessArticle

Vasorelaxation, Induced by Dictyota pulchella (Dictyotaceae), a Brown Alga, Is Mediated via Inhibition of Calcium Influx in Rats

by Thyago M. Queiroz, Natália T. Machado, Fabíola F. Furtado, Abrahão A. Oliveira-Filho, Maria C. Alustau, Camila S. Figueiredo, George E. C. Miranda, José M. Barbosa-Filho, Valdir A. Braga and Isac A. Medeiros

Mar. Drugs 2011, 9(10), 2075-2088; https://doi.org/10.3390/md9102075 - 24 Oct 2011

Cited by 12 | Viewed by 6943

Abstract

This study aimed to investigate the cardiovascular effects elicited by Dictyota pulchella, a brown alga, using in vivo and in vitro approaches. In normotensive conscious rats, CH₂Cl₂/MeOH Extract (CME, 5, 10, 20 and 40 mg/kg) from Dictyota pulchella [...] Read more.

This study aimed to investigate the cardiovascular effects elicited by Dictyota pulchella, a brown alga, using in vivo and in vitro approaches. In normotensive conscious rats, CH₂Cl₂/MeOH Extract (CME, 5, 10, 20 and 40 mg/kg) from Dictyota pulchella produced dose-dependent hypotension (−4 ± 1; −8 ± 2; −53 ± 8 and −63 ± 3 mmHg) and bradycardia (−8 ± 6; −17 ± 11; −257 ± 36 and −285 ± 27 b.p.m.). In addition, CME and Hexane/EtOAc Phase (HEP) (0.01–300 µg/mL) from Dictyota pulchella induced a concentration-dependent relaxation in phenylephrine (Phe, 1 µM)-pre-contracted mesenteric artery rings. The vasorelaxant effect was not modified by the removal of the vascular endothelium or pre-incubation with KCl (20 mM), tetraethylammonium (TEA, 3 mM) or tromboxane A₂ agonist U-46619 (100 nM). Furthermore, CME and HEP reversed CaCl₂-induced vascular contractions. These results suggest that both CME and HEP act on the voltage-operated calcium channel in order to produce vasorelaxation. In addition, CME induced vasodilatation after the vessels have been pre-contracted with L-type Ca²⁺ channel agonist (Bay K 8644, 200 nM). Taken together, our data show that CME induces hypotension and bradycardia in vivo and that both CME and HEP induce endothelium-independent vasodilatation in vitro that seems to involve the inhibition of the Ca²⁺ influx through blockade of voltage-operated calcium channels. Full article

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Open AccessReview

The Chemical Synthesis of Tetrodoxin: An Ongoing Quest

by Jaclyn Chau and Marco A. Ciufolini

Mar. Drugs 2011, 9(10), 2046-2074; https://doi.org/10.3390/md9102046 - 20 Oct 2011

Cited by 40 | Viewed by 12162

Abstract

This contribution reviews all the synthetic work on tetrodotoxin that has appeared in the literature through June 2011. Full article

(This article belongs to the Special Issue Tetrodotoxin 2011)

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Open AccessArticle

Bioactive Eunicellin-Based Diterpenoids from the Soft Coral Cladiella krempfi

by Chi-Jen Tai, Jui-Hsin Su, Ming-Shyan Huang, Zhi-Hong Wen, Chang-Feng Dai and Jyh-Horng Sheu

Mar. Drugs 2011, 9(10), 2036-2045; https://doi.org/10.3390/md9102036 - 19 Oct 2011

Cited by 37 | Viewed by 6662

Abstract

Four new eunicellin-based diterpenoids, krempfielins A–D (1–4), along with two known compounds (5 and 6) have been isolated from a soft coral Cladiella krempfi. The structures of the new metabolites were elucidated by extensive spectroscopic analysis [...] Read more.

Four new eunicellin-based diterpenoids, krempfielins A–D (1–4), along with two known compounds (5 and 6) have been isolated from a soft coral Cladiella krempfi. The structures of the new metabolites were elucidated by extensive spectroscopic analysis and by comparison with spectroscopic data of related known compounds. Compounds 5 and 6 were shown to exhibit cytotoxicity against a limited panel of cancer cell lines. Furthermore, compounds 2, 3, 5 and 6 were shown to exert significant in vitro anti-inflammatory activity against LPS-stimulated RAW264.7 macrophage cells. Full article

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Open AccessReview

Anti-Biofilm Compounds Derived from Marine Sponges

by Sean D. Stowe, Justin J. Richards, Ashley T. Tucker, Richele Thompson, Christian Melander and John Cavanagh

Mar. Drugs 2011, 9(10), 2010-2035; https://doi.org/10.3390/md9102010 - 19 Oct 2011

Cited by 105 | Viewed by 14837

Abstract

Bacterial biofilms are surface-attached communities of microorganisms that are protected by an extracellular matrix of biomolecules. In the biofilm state, bacteria are significantly more resistant to external assault, including attack by antibiotics. In their native environment, bacterial biofilms underpin costly biofouling that wreaks [...] Read more.

Bacterial biofilms are surface-attached communities of microorganisms that are protected by an extracellular matrix of biomolecules. In the biofilm state, bacteria are significantly more resistant to external assault, including attack by antibiotics. In their native environment, bacterial biofilms underpin costly biofouling that wreaks havoc on shipping, utilities, and offshore industry. Within a host environment, they are insensitive to antiseptics and basic host immune responses. It is estimated that up to 80% of all microbial infections are biofilm-based. Biofilm infections of indwelling medical devices are of particular concern, since once the device is colonized, infection is almost impossible to eliminate. Given the prominence of biofilms in infectious diseases, there is a notable effort towards developing small, synthetically available molecules that will modulate bacterial biofilm development and maintenance. Here, we highlight the development of small molecules that inhibit and/or disperse bacterial biofilms specifically through non-microbicidal mechanisms. Importantly, we discuss several sets of compounds derived from marine sponges that we are developing in our labs to address the persistent biofilm problem. We will discuss: discovery/synthesis of natural products and their analogues—including our marine sponge-derived compounds and initial adjuvant activity and toxicological screening of our novel anti-biofilm compounds. Full article

(This article belongs to the Special Issue Bioactive Compound from Marine Sponges)

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Graphical abstract

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Open AccessArticle

Pardaxin, an Antimicrobial Peptide, Triggers Caspase-Dependent and ROS-Mediated Apoptosis in HT-1080 Cells

by Tsui-Chin Huang, Jheng-Fong Lee and Jyh-Yih Chen

Mar. Drugs 2011, 9(10), 1995-2009; https://doi.org/10.3390/md9101995 - 19 Oct 2011

Cited by 76 | Viewed by 8585

Abstract

Pardaxin is an antimicrobial peptide (AMP) that was first isolated from secretions of the Red Sea Moses sole. The role of pardaxin in inducing apoptosis for preventing cancer has not yet been investigated. In the present study, we examined the antitumor activity of [...] Read more.

Pardaxin is an antimicrobial peptide (AMP) that was first isolated from secretions of the Red Sea Moses sole. The role of pardaxin in inducing apoptosis for preventing cancer has not yet been investigated. In the present study, we examined the antitumor activity of pardaxin against human fibrosarcoma HT-1080 cells; pardaxin inhibited cell proliferation by inducing apoptosis, as demonstrated by an increase in the externalization of plasma membrane phosphatidylserine and the presence of chromatin condensation. Additionally, pardaxin-treated cells showed elevation of caspase-3/7 activities, disruption of the mitochondrial membrane potential, and accumulation of reactive oxygen species (ROS) production. Inhibition of ROS production and caspase-3/7 activities reduced pardaxin-induced effects. Taken together, these findings suggest that pardaxin may be a potential anticancer agent for selectively inducing apoptosis in cancer cells. Full article

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Open AccessArticle

Inducible ASABF-Type Antimicrobial Peptide from the Sponge Suberites domuncula: Microbicidal and Hemolytic Activity in Vitro and Toxic Effect on Molluscs in Vivo

by Matthias Wiens, Heinz C. Schröder, Michael Korzhev, Xiao-Hong Wang, Renato Batel and Werner E. G. Müller

Mar. Drugs 2011, 9(10), 1969-1994; https://doi.org/10.3390/md9101969 - 19 Oct 2011

Cited by 20 | Viewed by 7453

Abstract

Since sponges, as typical filter-feeders, are exposed to a high load of attacking prokaryotic and eukaryotic organisms, they are armed with a wide arsenal of antimicrobial/cytostatic low-molecular-weight, non-proteinaceous bioactive compounds. Here we present the first sponge agent belonging to the group of ASABF-type [...] Read more.

Since sponges, as typical filter-feeders, are exposed to a high load of attacking prokaryotic and eukaryotic organisms, they are armed with a wide arsenal of antimicrobial/cytostatic low-molecular-weight, non-proteinaceous bioactive compounds. Here we present the first sponge agent belonging to the group of ASABF-type antimicrobial peptides. The ASABF gene was identified and cloned from the demospongeSuberites domuncula. The mature peptide, with a length of 64 aa residues has a predicted pI of 9.24, and comprises the characteristic CSαβ structural motif. Consequently, the S. domuncula ASABF shares high similarity with the nematode ASABFs; it is distantly related to the defensins. The recombinant peptide was found to display besides microbicidal activity, anti-fungal activity. In addition, the peptide lyses human erythrocytes. The expression ofASABF is upregulated after exposure to the apoptosis-inducing agent 2,2'-dipyridyl. During the process of apoptosis of surface tissue of S. domuncula, grazing gastropods (Bittium sp.) are attracted by quinolinic acid which is synthesized through the kynurenine pathway by the enzyme 3-hydroxyanthranilate 3,4-dioxygenase (HAD). Finally, the gastropods are repelled from the sponge tissue by the ASABF. It is shown that the effector peptide ASABF is sequentially expressed after the induction of the HAD gene and a caspase, as a central enzyme executing apoptosis. Full article

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Open AccessArticle

Bioactive Cembranoids from the Soft Coral Sinularia crassa

by Chih-Hua Chao, Kuei-Ju Chou, Chiung-Yao Huang, Zhi-Hong Wen, Chi-Hsin Hsu, Yang-Chang Wu, Chang-Feng Dai and Jyh-Horng Sheu

Mar. Drugs 2011, 9(10), 1955-1968; https://doi.org/10.3390/md9101955 - 17 Oct 2011

Cited by 41 | Viewed by 7447

Abstract

Eight new cembranoids, crassarines A–H (1–8) were isolated from the Formosan soft coral Sinularia crassa. Compounds 1–3 represent the rare cembranoids with a 1,12-oxa-bridged tetrahydrofuran ring, while 4 and 5 are the firstly discovered 1,11-oxa-bridged tetrahydropyranocembranoids. [...] Read more.

Eight new cembranoids, crassarines A–H (1–8) were isolated from the Formosan soft coral Sinularia crassa. Compounds 1–3 represent the rare cembranoids with a 1,12-oxa-bridged tetrahydrofuran ring, while 4 and 5 are the firstly discovered 1,11-oxa-bridged tetrahydropyranocembranoids. The absolute configuration of 6 was determined using the Mosher’s method. Compounds 6 and 8 were found to significantly inhibit the expression of both pro-inflammatory iNOS and COX-2 proteins at 10 µM, respectively, while compounds 4–8 were found to be non-cytotoxic toward the selected human liver cancer cells. Full article

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Graphical abstract

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Open AccessReview

The Structural Diversity of Carbohydrate Antigens of Selected Gram-Negative Marine Bacteria

by Evgeny L. Nazarenko, Russell J. Crawford and Elena P. Ivanova

Mar. Drugs 2011, 9(10), 1914-1954; https://doi.org/10.3390/md9101914 - 14 Oct 2011

Cited by 38 | Viewed by 10339

Abstract

Marine microorganisms have evolved for millions of years to survive in the environments characterized by one or more extreme physical or chemical parameters, e.g., high pressure, low temperature or high salinity. Marine bacteria have the ability to produce a range of biologically active [...] Read more.

Marine microorganisms have evolved for millions of years to survive in the environments characterized by one or more extreme physical or chemical parameters, e.g., high pressure, low temperature or high salinity. Marine bacteria have the ability to produce a range of biologically active molecules, such as antibiotics, toxins and antitoxins, antitumor and antimicrobial agents, and as a result, they have been a topic of research interest for many years. Among these biologically active molecules, the carbohydrate antigens, lipopolysaccharides (LPSs, O-antigens) found in cell walls of Gram-negative marine bacteria, show great potential as candidates in the development of drugs to prevent septic shock due to their low virulence. The structural diversity of LPSs is thought to be a reflection of the ability for these bacteria to adapt to an array of habitats, protecting the cell from being compromised by exposure to harsh environmental stress factors. Over the last few years, the variety of structures of core oligosaccharides and O-specific polysaccharides from LPSs of marine microrganisms has been discovered. In this review, we discuss the most recently encountered structures that have been identified from bacteria belonging to the genera Aeromonas, Alteromonas, Idiomarina, Microbulbifer, Pseudoalteromonas, Plesiomonas and Shewanella of the Gammaproteobacteria phylum; Sulfitobacter and Loktanella of the Alphaproteobactera phylum and to the genera Arenibacter, Cellulophaga, Chryseobacterium, Flavobacterium, Flexibacter of the Cytophaga-Flavobacterium-Bacteroides phylum. Particular attention is paid to the particular chemical features of the LPSs, such as the monosaccharide type, non-sugar substituents and phosphate groups, together with some of the typifying traits of LPSs obtained from marine bacteria. A possible correlation is then made between such features and the environmental adaptations undertaken by marine bacteria. Full article

(This article belongs to the Collection Marine Polysaccharides)

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Open AccessArticle

Antiparasitic Bromotyrosine Derivatives from the Marine Sponge Verongula rigida

by Elkin Galeano, Olivier P. Thomas, Sara Robledo, Diana Munoz and Alejandro Martinez

Mar. Drugs 2011, 9(10), 1902-1913; https://doi.org/10.3390/md9101902 - 14 Oct 2011

Cited by 35 | Viewed by 10325

Abstract

Nine bromotyrosine-derived compounds were isolated from the Caribbean marine sponge Verongula rigida. Two of them, aeroplysinin-1 (1) and dihydroxyaerothionin (2), are known compounds for this species, and the other seven are unknown compounds for this species, namely: 3,5-dibromo- [...] Read more.

Nine bromotyrosine-derived compounds were isolated from the Caribbean marine sponge Verongula rigida. Two of them, aeroplysinin-1 (1) and dihydroxyaerothionin (2), are known compounds for this species, and the other seven are unknown compounds for this species, namely: 3,5-dibromo-N,N,N-trimethyltyraminium (3), 3,5-dibromo-N,N,N, O-tetramethyltyraminium (4), purealidin R (5), 19-deoxyfistularin 3 (6), purealidin B (7), 11-hydroxyaerothionin (8) and fistularin-3 (9). Structural determination of the isolated compounds was performed using one- and two-dimensional NMR, MS and other spectroscopy data. All isolated compounds were screened for their in vitro activity against three parasitic protozoa: Leishmania panamensis, Plasmodium falciparum and Trypanosoma cruzi. Compounds 7 and 8 showed selective antiparasitic activity at 10 and 5 µM against Leishmania and Plasmodium parasites, respectively. Cytotoxicity of these compounds on a human promonocytic cell line was also assessed. Full article

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Open AccessArticle

Studies on Synthesis and Structure-Activity Relationship (SAR) of Derivatives of a New Natural Product from Marine Fungi as Inhibitors of Influenza Virus Neuraminidase

by Jing Li, Dingmei Zhang, Xun Zhu, Zhenjian He, Shu Liu, Mengfeng Li, Jiyan Pang and Yongcheng Lin

Mar. Drugs 2011, 9(10), 1887-1901; https://doi.org/10.3390/md9101887 - 11 Oct 2011

Cited by 18 | Viewed by 11719

Abstract

Based on the natural isoprenyl phenyl ether from a mangrove-derived fungus, 32 analogues were synthesized and evaluated for inhibitory activity against influenza H1N1 neuraminidase. Compound 15 (3-(allyloxy)-4-hydroxybenzaldehyde) exhibited the most potent inhibitory activity, with IC₅₀ values of 26.96 μM for A/GuangdongSB/01/2009 (H1N1), [...] Read more.

Based on the natural isoprenyl phenyl ether from a mangrove-derived fungus, 32 analogues were synthesized and evaluated for inhibitory activity against influenza H1N1 neuraminidase. Compound 15 (3-(allyloxy)-4-hydroxybenzaldehyde) exhibited the most potent inhibitory activity, with IC₅₀ values of 26.96 μM for A/GuangdongSB/01/2009 (H1N1), 27.73 μM for A/Guangdong/03/2009 (H1N1), and 25.13 μM for A/Guangdong/05/2009 (H1N1), respectively, which is stronger than the benzoic acid derivatives (~mM level). These are a new kind of non-nitrogenous aromatic ether Neuraminidase (NA) inhibitors. Their structures are simple and the synthesis routes are not complex. The structure-activity relationship (SAR) analysis revealed that the aryl aldehyde and unsubstituted hydroxyl were important to NA inhibitory activities. Molecular docking studies were carried out to explain the SAR of the compounds, and provided valuable information for further structure modification. Full article

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Graphical abstract

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Open AccessReview

Cnidarians as a Source of New Marine Bioactive Compounds—An Overview of the Last Decade and Future Steps for Bioprospecting

by Joana Rocha, Luisa Peixe, Newton C.M. Gomes and Ricardo Calado

Mar. Drugs 2011, 9(10), 1860-1886; https://doi.org/10.3390/md9101860 - 10 Oct 2011

Cited by 208 | Viewed by 17570

Abstract

Marine invertebrates are rich sources of bioactive compounds and their biotechnological potential attracts scientific and economic interest worldwide. Although sponges are the foremost providers of marine bioactive compounds, cnidarians are also being studied with promising results. This diverse group of marine invertebrates includes [...] Read more.

Marine invertebrates are rich sources of bioactive compounds and their biotechnological potential attracts scientific and economic interest worldwide. Although sponges are the foremost providers of marine bioactive compounds, cnidarians are also being studied with promising results. This diverse group of marine invertebrates includes over 11,000 species, 7500 of them belonging to the class Anthozoa. We present an overview of some of the most promising marine bioactive compounds from a therapeutic point of view isolated from cnidarians in the first decade of the 21st century. Anthozoan orders Alcyonacea and Gorgonacea exhibit by far the highest number of species yielding promising compounds. Antitumor activity has been the major area of interest in the screening of cnidarian compounds, the most promising ones being terpenoids (monoterpenoids, diterpenoids, sesquiterpenoids). We also discuss the future of bioprospecting for new marine bioactive compounds produced by cnidarians. Full article

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Open AccessReview

Antitumor Peptides from Marine Organisms

by Lan-Hong Zheng, Yue-Jun Wang, Jun Sheng, Fang Wang, Yuan Zheng, Xiu-Kun Lin and Mi Sun

Mar. Drugs 2011, 9(10), 1840-1859; https://doi.org/10.3390/md9101840 - 10 Oct 2011

Cited by 131 | Viewed by 12267

Abstract

The biodiversity of the marine environment and the associated chemical diversity constitute a practically unlimited resource of new antitumor agents in the field of the development of marine bioactive substances. In this review, the progress on studies of antitumor peptides from marine sources [...] Read more.

The biodiversity of the marine environment and the associated chemical diversity constitute a practically unlimited resource of new antitumor agents in the field of the development of marine bioactive substances. In this review, the progress on studies of antitumor peptides from marine sources is provided. The biological properties and mechanisms of action of different marine peptides are described; information about their molecular diversity is also presented. Novel peptides that induce apoptosis signal pathway, affect the tubulin-microtubule equilibrium and inhibit angiogenesis are presented in association with their pharmacological properties. It is intended to provide useful information for further research in the fields of marine antitumor peptides. Full article

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Open AccessArticle

Polyhydroxylated Steroids from the Bamboo Coral Isis hippuris

by Wei-Hua Chen, Shang-Kwei Wang and Chang-Yih Duh

Mar. Drugs 2011, 9(10), 1829-1839; https://doi.org/10.3390/md9101829 - 10 Oct 2011

Cited by 22 | Viewed by 8160

Abstract

In previous studies on the secondary metabolites of the Taiwanese octocoral Isis hippuris, specimens have always been collected at Green Island. In the course of our studies on bioactive compounds from marine organisms, the acetone-solubles of the Taiwanese octocoral I. hippuris collected [...] Read more.

In previous studies on the secondary metabolites of the Taiwanese octocoral Isis hippuris, specimens have always been collected at Green Island. In the course of our studies on bioactive compounds from marine organisms, the acetone-solubles of the Taiwanese octocoral I. hippuris collected at Orchid Island have led to the isolation of five new polyoxygenated steroids: hipposterone M–O (1–3), hipposterol G (4) and hippuristeroketal A (5). The structures of these compounds were determined on the basis of their spectroscopic and physical data. The anti-HCMV (human cytomegalovirus) activity of 1–5 and their cytotoxicity against selected cell lines were evaluated. Compound 2 exhibited inhibitory activity against HCMV, with an EC₅₀ value of 6.0 μg/mL. Full article

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Open AccessReview

Fucoxanthin, a Marine Carotenoid Present in Brown Seaweeds and Diatoms: Metabolism and Bioactivities Relevant to Human Health

by Juan Peng, Jian-Ping Yuan, Chou-Fei Wu and Jiang-Hai Wang

Mar. Drugs 2011, 9(10), 1806-1828; https://doi.org/10.3390/md9101806 - 10 Oct 2011

Cited by 566 | Viewed by 29213

Abstract

The marine carotenoid fucoxanthin can be found in marine brown seaweeds, the macroalgae, and diatoms, the microalgae, and has remarkable biological properties. Numerous studies have shown that fucoxanthin has considerable potential and promising applications in human health. In this article, we review the [...] Read more.

The marine carotenoid fucoxanthin can be found in marine brown seaweeds, the macroalgae, and diatoms, the microalgae, and has remarkable biological properties. Numerous studies have shown that fucoxanthin has considerable potential and promising applications in human health. In this article, we review the current available scientific literature regarding the metabolism, safety, and bioactivities of fucoxanthin, including its antioxidant, anti-inflammatory, anticancer, anti-obese, antidiabetic, antiangiogenic and antimalarial activities, and its protective effects on the liver, blood vessels of the brain, bones, skin, and eyes. Although some studies have shown the bioavailability of fucoxanthin in brown seaweeds to be low in humans, many studies have suggested that a dietary combination of fucoxanthin and edible oil or lipid could increase the absorption rate of fucoxanthin, and thus it might be a promising marine drug. Full article

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Open AccessReview

High-Value Components and Bioactives from Sea Cucumbers for Functional Foods—A Review

by Sara Bordbar, Farooq Anwar and Nazamid Saari

Mar. Drugs 2011, 9(10), 1761-1805; https://doi.org/10.3390/md9101761 - 10 Oct 2011

Cited by 605 | Viewed by 29516

Abstract

Sea cucumbers, belonging to the class Holothuroidea, are marine invertebrates, habitually found in the benthic areas and deep seas across the world. They have high commercial value coupled with increasing global production and trade. Sea cucumbers, informally named as bêche-de-mer, or gamat, [...] Read more.

Sea cucumbers, belonging to the class Holothuroidea, are marine invertebrates, habitually found in the benthic areas and deep seas across the world. They have high commercial value coupled with increasing global production and trade. Sea cucumbers, informally named as bêche-de-mer, or gamat, have long been used for food and folk medicine in the communities of Asia and Middle East. Nutritionally, sea cucumbers have an impressive profile of valuable nutrients such as Vitamin A, Vitamin B1 (thiamine), Vitamin B2 (riboflavin), Vitamin B3 (niacin), and minerals, especially calcium, magnesium, iron and zinc. A number of unique biological and pharmacological activities including anti-angiogenic, anticancer, anticoagulant, anti-hypertension, anti-inflammatory, antimicrobial, antioxidant, antithrombotic, antitumor and wound healing have been ascribed to various species of sea cucumbers. Therapeutic properties and medicinal benefits of sea cucumbers can be linked to the presence of a wide array of bioactives especially triterpene glycosides (saponins), chondroitin sulfates, glycosaminoglycan (GAGs), sulfated polysaccharides, sterols (glycosides and sulfates), phenolics, cerberosides, lectins, peptides, glycoprotein, glycosphingolipids and essential fatty acids. This review is mainly designed to cover the high-value components and bioactives as well as the multiple biological and therapeutic properties of sea cucumbers with regard to exploring their potential uses for functional foods and nutraceuticals. Full article

(This article belongs to the Special Issue Marine Functional Food)

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Open AccessReview

Therapies from Fucoidan; Multifunctional Marine Polymers

by Janet Helen Fitton

Mar. Drugs 2011, 9(10), 1731-1760; https://doi.org/10.3390/md9101731 - 30 Sep 2011

Cited by 283 | Viewed by 20132

Abstract

Published research on fucoidans increased three fold between 2000 and 2010. These algal derived marine carbohydrate polymers present numerous valuable bioactivities. This review discusses the role for fucoidan in the control of acute and chronic inflammation via selectin blockade, enzyme inhibition and inhibiting [...] Read more.

Published research on fucoidans increased three fold between 2000 and 2010. These algal derived marine carbohydrate polymers present numerous valuable bioactivities. This review discusses the role for fucoidan in the control of acute and chronic inflammation via selectin blockade, enzyme inhibition and inhibiting the complement cascade. The recent data on toxicology and uptake of fucoidan is detailed together with a discussion on the comparative activities of fractions of fucoidan from different sources. Recent in vivo, in vitro and clinical research related to diverse clinical needs is discussed. Targets include osteoarthritis, kidney and liver disease, neglected infectious diseases, hemopoietic stem cell modulation, protection from radiation damage and treatments for snake envenomation. In recent years, the production of well characterized reproducible fucoidan fractions on a commercial scale has become possible making therapies from fucoidan a realizable goal. Full article

(This article belongs to the Collection Marine Polysaccharides)

202 KiB

Open AccessArticle

Seasonal Dynamics of Microcystis spp. and Their Toxigenicity as Assessed by qPCR in a Temperate Reservoir

by António Martins, Cristiana Moreira, Micaela Vale, Marisa Freitas, Ana Regueiras, Agostinho Antunes and Vitor Vasconcelos

Mar. Drugs 2011, 9(10), 1715-1730; https://doi.org/10.3390/md9101715 - 29 Sep 2011

Cited by 29 | Viewed by 10141

Abstract

Blooms of toxic cyanobacteria are becoming increasingly frequent, mainly due to water quality degradation. This work applied qPCR as a tool for early warning of microcystin(MC)-producer cyanobacteria and risk assessment of water supplies. Specific marker genes for cyanobacteria, Microcystis and MC-producing Microcystis, [...] Read more.

Blooms of toxic cyanobacteria are becoming increasingly frequent, mainly due to water quality degradation. This work applied qPCR as a tool for early warning of microcystin(MC)-producer cyanobacteria and risk assessment of water supplies. Specific marker genes for cyanobacteria, Microcystis and MC-producing Microcystis, were quantified to determine the genotypic composition of the natural Microcystis population. Correlations between limnological parameters, pH, water temperature, dissolved oxygen and conductivity and MC concentrations as well as Microcystis abundance were assessed. A negative significant correlation was observed between toxic (with mcy genes) to non-toxic (without mcy genes) genotypes ratio and the overall Microcystis density. The highest proportions of toxic Microcystis genotypes were found 4–6 weeks before and 8–10 weeks after the peak of the bloom, with the lowest being observed at its peak. These results suggest positive selection of non-toxic genotypes under favorable environmental growth conditions. Significant positive correlations could be found between quantity of toxic genotypes and MC concentration, suggesting that the method applied can be useful to predict potential MC toxicity risk. No significant correlation was found between the limnological parameters measured and MC concentrations or toxic genotypes proportions indicating that other abiotic and biotic factors should be governing MC production and toxic genotypes dynamics. The qPCR method here applied is useful to rapidly estimate the potential toxicity of environmental samples and so, it may contribute to the more efficient management of water use in eutrophic systems. Full article

(This article belongs to the Special Issue Algal Toxins)

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3439 KiB

Open AccessArticle

Design of New α-Conotoxins: From Computer Modeling to Synthesis of Potent Cholinergic Compounds

by Igor E. Kasheverov, Maxim N. Zhmak, Alexey Y. Khruschov and Victor I. Tsetlin

Mar. Drugs 2011, 9(10), 1698-1714; https://doi.org/10.3390/md9101698 - 28 Sep 2011

Cited by 25 | Viewed by 6734

Abstract

A series of 14 new analogs of α-conotoxin PnIA Conus pennaceus was synthesized and tested for binding to the human α7 nicotinic acetylcholine receptor (nAChR) and acetylcholine-binding proteins (AChBP) Lymnaea stagnalis and Aplysia californica. Based on computer modeling and the X-ray structure [...] Read more.

A series of 14 new analogs of α-conotoxin PnIA Conus pennaceus was synthesized and tested for binding to the human α7 nicotinic acetylcholine receptor (nAChR) and acetylcholine-binding proteins (AChBP) Lymnaea stagnalis and Aplysia californica. Based on computer modeling and the X-ray structure of the A. californica AChBP complex with the PnIA[A10L, D14K] analog [1], single and multiple amino acid substitutions were introduced in α-conotoxin PnIA aimed at compounds of higher affinity and selectivity. Three analogs, PnIA[L5H], PnIA[A10L, D14K] and PnIA[L5R, A10L, D14R], have high affinities for AChBPs or α7 nAChR, as found in competition with radioiodinated α-bungarotoxin. That is why we prepared radioiodinated derivatives of these α-conotoxins, demonstrated their specific binding and found that among the tested synthetic analogs, most had almost 10-fold higher affinity in competition with radioactive α-conotoxins as compared to competition with radioactive α-bungarotoxin. Thus, radioiodinated α-conotoxins are a more sensitive tool for checking the activity of novel α-conotoxins and other compounds quickly dissociating from the receptor complexes. Full article

(This article belongs to the Special Issue Conotoxins)

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826 KiB

Open AccessArticle

New Tetromycin Derivatives with Anti-Trypanosomal and Protease Inhibitory Activities

by Sheila M. Pimentel-Elardo, Verena Buback, Tobias A.M. Gulder, Tim S. Bugni, Jason Reppart, Gerhard Bringmann, Chris M. Ireland, Tanja Schirmeister and Ute Hentschel

Mar. Drugs 2011, 9(10), 1682-1697; https://doi.org/10.3390/md9101682 - 26 Sep 2011

Cited by 26 | Viewed by 9355

Abstract

Four new tetromycin derivatives, tetromycins 1–4 and a previously known one, tetromycin B (5) were isolated from Streptomyces axinellae Pol001^T cultivated from the Mediterranean sponge Axinella polypoides. Structures were assigned using extensive 1D and 2D NMR spectroscopy [...] Read more.

Four new tetromycin derivatives, tetromycins 1–4 and a previously known one, tetromycin B (5) were isolated from Streptomyces axinellae Pol001^T cultivated from the Mediterranean sponge Axinella polypoides. Structures were assigned using extensive 1D and 2D NMR spectroscopy as well as HRESIMS analysis. The compounds were tested for antiparasitic activities against Leishmania major and Trypanosoma brucei, and for protease inhibition against several cysteine proteases such as falcipain, rhodesain, cathepsin L, cathepsin B, and viral proteases SARS-CoV M^pro, and PL^pro. The compounds showed antiparasitic activities against T. brucei and time-dependent inhibition of cathepsin L-like proteases with K_i values in the low micromolar range. Full article

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Mar. Drugs, Volume 9, Issue 10 (October 2011) – 23 articles , Pages 1682-2163

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