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Mar. Drugs, Volume 11, Issue 5 (May 2013), Pages 1427-1762

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Research

Jump to: Review, Other

Open AccessArticle Total Synthesis and Biological Activity of Marine Alkaloid Eudistomins Y1–Y7 and Their Analogues
Mar. Drugs 2013, 11(5), 1427-1439; doi:10.3390/md11051427
Received: 25 February 2013 / Revised: 25 March 2013 / Accepted: 7 April 2013 / Published: 29 April 2013
Cited by 8 | PDF Full-text (658 KB) | HTML Full-text | XML Full-text
Abstract
Eudistomin Y class compounds are a series of β-carbolines which was originally isolated from a marine turnicate or ascidian near the South Korea Sea. These compounds contain bromo-substituted groups, which is one of the typical characters of marine natural products. We report [...] Read more.
Eudistomin Y class compounds are a series of β-carbolines which was originally isolated from a marine turnicate or ascidian near the South Korea Sea. These compounds contain bromo-substituted groups, which is one of the typical characters of marine natural products. We report herein the chemical synthesis and biological evaluation of seven new β-carboline-based metabolites, Eudistomins Y1–Y7, and their hydroxyl-methylated phenyl derivatives. Using bromo-substituted tryptamines and bromo-substituted phenylglyoxals as the key intermediates, Eudistomins Y1–Y7 and their derivatives were synthesized via the acid-catalyzed Pictet-Spengler reaction and fully characterized by 1H- and 13C-NMR and mass spectroscopy. Biological studies revealed that all of the compounds showed moderate growth inhibitory activity against breast carcinoma cell line MDA-231 with IC50 of 15–63 μM and the inhibitory activities of hydroxyl-methylated phenyl products were higher than that of the corresponding natural products Eudistomins Y1–Y7. Full article
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Open AccessArticle Neuritogenic and Neuroprotective Effects of Polar Steroids from the Far East Starfishes Patiria pectinifera and Distolasterias nipon
Mar. Drugs 2013, 11(5), 1440-1455; doi:10.3390/md11051440
Received: 5 March 2013 / Revised: 18 April 2013 / Accepted: 22 April 2013 / Published: 3 May 2013
Cited by 11 | PDF Full-text (1137 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The neuritogenic and neuroprotective activities of six starfish polar steroids, asterosaponin Р1, (25S)-5α-cholestane-3β,4β,6α,7α,8,15α,16β,26-octaol, and (25S)-5α-cholestane-3β,6α,7α,8,15α,16β,26-heptaol (13) from the starfish Patiria pectinifera and distolasterosides D1–D3 (46) [...] Read more.
The neuritogenic and neuroprotective activities of six starfish polar steroids, asterosaponin Р1, (25S)-5α-cholestane-3β,4β,6α,7α,8,15α,16β,26-octaol, and (25S)-5α-cholestane-3β,6α,7α,8,15α,16β,26-heptaol (13) from the starfish Patiria pectinifera and distolasterosides D1–D3 (46) from the starfish Distolasterias nipon were analyzed using the mouse neuroblastoma (NB) C-1300 cell line and an organotypic rat hippocampal slice culture (OHSC). All of these compounds enhanced neurite outgrowth in NB cells. Dose-dependent responses to compounds 13 were observed within the concentration range of 10–100 nM, and dose-dependent responses to glycosides 46 were observed at concentrations of 1–50 nM. All the tested substances exhibited notable synergistic effects with trace amounts of nerve growth factor (NGF, 1 ng/mL) or brain-derived neurotrophic factor (BDNF, 0.1 ng/mL). Using NB cells and OHSCs, it was shown for the first time that starfish steroids 16 act as neuroprotectors against oxygen-glucose deprivation (OGD) by increasing the number of surviving cells. Altogether, these results suggest that neurotrophin-like neuritogenic and neuroprotective activities are most likely common properties of starfish polyhydroxysteroids and the related glycosides, although the magnitude of the effect depended on the particular compound structure. Full article
Open AccessArticle Structural Characteristics and Anticancer Activity of Fucoidan from the Brown Alga Sargassum mcclurei
Mar. Drugs 2013, 11(5), 1456-1476; doi:10.3390/md11051456
Received: 11 February 2013 / Revised: 10 April 2013 / Accepted: 23 April 2013 / Published: 6 May 2013
Cited by 16 | PDF Full-text (702 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Three different fucoidan fractions were isolated and purified from the brown alga, Sargassum mcclurei. The SmF1 and SmF2 fucoidans are sulfated heteropolysaccharides that contain fucose, galactose, mannose, xylose and glucose. The SmF3 fucoidan is highly sulfated (35%) galactofucan, and the main [...] Read more.
Three different fucoidan fractions were isolated and purified from the brown alga, Sargassum mcclurei. The SmF1 and SmF2 fucoidans are sulfated heteropolysaccharides that contain fucose, galactose, mannose, xylose and glucose. The SmF3 fucoidan is highly sulfated (35%) galactofucan, and the main chain of the polysaccharide contains a →3)-α-l-Fucp(2,4SO3)-(1→3)-α-l-Fucp(2,4SO3)-(1→ motif with 1,4-linked 3-sulfated α-l-Fucp inserts and 6-linked galactose on reducing end. Possible branching points include the 1,2,6- or 1,3,6-linked galactose and/or 1,3,4-linked fucose residues that could be glycosylated with terminal β-d-Galp residues or chains of alternating sulfated 1,3-linked α-l-Fucp and 1,4-linked β-d-Galp residues, which have been identified in galactofucans for the first time. Both α-l-Fucp and β-d-Galp residues are sulfated at C-2 and/or C-4 (and some C-6 of β-d-Galp) and potentially the C-3 of terminal β-d-Galp, 1,4-linked β-d-Galp and 1,4-linked α-l-Fucp residues. All fucoidans fractions were less cytotoxic and displayed colony formation inhibition in colon cancer DLD-1 cells. Therefore, these fucoidan fractions are potential antitumor agents. Full article
Open AccessArticle Balibalosides, an Original Family of Glucosylated Sesterterpenes Produced by the Mediterranean Sponge Oscarella balibaloi
Mar. Drugs 2013, 11(5), 1477-1489; doi:10.3390/md11051477
Received: 25 March 2013 / Revised: 9 April 2013 / Accepted: 22 April 2013 / Published: 6 May 2013
Cited by 7 | PDF Full-text (555 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The chemical investigation of the recently described Mediterranean Homoscleromorpha sponge Oscarella balibaloi revealed an original family of five closely related glucosylated sesterterpenes 14, named balibalosides. Their structure elucidation was mainly inferred from NMR and HRMS data analyses. Balibalosides differ [...] Read more.
The chemical investigation of the recently described Mediterranean Homoscleromorpha sponge Oscarella balibaloi revealed an original family of five closely related glucosylated sesterterpenes 14, named balibalosides. Their structure elucidation was mainly inferred from NMR and HRMS data analyses. Balibalosides differ by the pattern of acetyl substitutions on the three sugar residues linked to the same aglycone sesterterpenoid core. From a biosynthetic perspective, these compounds may represent intermediates in the pathways leading to more complex sesterterpenes frequently found in Dictyoceratida, a sponge Order belonging to Demospongiae, a clade which is phylogenetically distinct from the Homoscleromorpha. While steroid and triterpenoid saponins were already well known from marine sponges, balibalosides are the first examples of glycosilated sesterterpenes. Full article
(This article belongs to the Special Issue Marine Secondary Metabolites)
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Open AccessArticle A Shark Liver Gene-Derived Active Peptide Expressed in the Silkworm, Bombyx mori: Preliminary Studies for Oral Administration of the Recombinant Protein
Mar. Drugs 2013, 11(5), 1492-1505; doi:10.3390/md11051492
Received: 12 February 2013 / Revised: 26 April 2013 / Accepted: 28 April 2013 / Published: 7 May 2013
Cited by 4 | PDF Full-text (661 KB) | HTML Full-text | XML Full-text
Abstract
Active peptide from shark liver (APSL) is a cytokine from Chiloscyllium plagiosum that can stimulate liver regeneration and protects the pancreas. To study the effect of orally administered recombinant APSL (rAPSL) on an animal model of type 2 diabetes mellitus, the APSL [...] Read more.
Active peptide from shark liver (APSL) is a cytokine from Chiloscyllium plagiosum that can stimulate liver regeneration and protects the pancreas. To study the effect of orally administered recombinant APSL (rAPSL) on an animal model of type 2 diabetes mellitus, the APSL gene was cloned, and APSL was expressed in Bombyx mori N cells (BmN cells), silkworm larvae and silkworm pupae using the silkworm baculovirus expression vector system (BEVS). It was demonstrated that rAPSL was able to significantly reduce the blood glucose level in mice with type 2 diabetes induced by streptozotocin. The analysis of paraffin sections of mouse pancreatic tissues revealed that rAPSL could effectively protect mouse islets from streptozotocin-induced lesions. Compared with the powder prepared from normal silkworm pupae, the powder prepared from pupae expressing rAPSL exhibited greater protective effects, and these results suggest that rAPSL has potential uses as an oral drug for the treatment of diabetes mellitus in the future. Full article
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Open AccessArticle Photoprotective Bioactivity Present in a Unique Marine Bacteria Collection from Portuguese Deep Sea Hydrothermal Vents
Mar. Drugs 2013, 11(5), 1506-1523; doi:10.3390/md11051506
Received: 13 March 2013 / Revised: 16 April 2013 / Accepted: 23 April 2013 / Published: 10 May 2013
Cited by 5 | PDF Full-text (876 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Interesting biological activities have been found for numerous marine compounds. In fact, screening of phylogenetically diverse marine microorganisms from extreme environments revealed to be a rational approach for the discovery of novel molecules with relevant bioactivities for industries such as pharmaceutical and [...] Read more.
Interesting biological activities have been found for numerous marine compounds. In fact, screening of phylogenetically diverse marine microorganisms from extreme environments revealed to be a rational approach for the discovery of novel molecules with relevant bioactivities for industries such as pharmaceutical and cosmeceutical. Nevertheless, marine sources deliverables are still far from the expectations and new extreme sources of microbes should be explored. In this work, a marine prokaryotic collection from four Mid-Atlantic Ridge (MAR) deep sea hydrothermal vents near the Azores Islands, Portugal, was created, characterized and tested for its photoprotective capacity. Within 246 isolates, a polyphasic approach, using chemotaxonomic and molecular typing methods, identified 23-related clusters of phenetically similar isolates with high indexes of diversity. Interestingly, 16S rRNA gene sequencing suggested the presence of 43% new prokaryotic species. A sub-set of 139 isolates of the prokaryotic collection was selected for biotechnological exploitation with 484 bacterial extracts prepared in a sustainable upscalling manner. 22% of the extracts showed an industrially relevant photoprotective activity, with two extracts, belonging to new strains of the species Shewanella algae and Vibrio fluvialis, uniquely showing UV-A, UV-B and UV-C protective capacity. This clearly demonstrates the high potential of the bacteria MAR vents collection in natural product synthesis with market applications. Full article
(This article belongs to the Special Issue Deep-Sea Natural Products)
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Open AccessArticle Tetroazolemycins A and B, Two New Oxazole-Thiazole Siderophores from Deep-Sea Streptomyces olivaceus FXJ8.012
Mar. Drugs 2013, 11(5), 1524-1533; doi:10.3390/md11051524
Received: 16 February 2013 / Revised: 18 April 2013 / Accepted: 24 April 2013 / Published: 10 May 2013
Cited by 6 | PDF Full-text (747 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Two new oxazole/thiazole derivatives, named tetroazolemycins A (1) and B (2), have been isolated from the acetone extract of the mycelium of Streptomyces olivaceus FXJ8.012 derived from deep-sea water, together with three known compounds, spoxazomicins A–C (3 [...] Read more.
Two new oxazole/thiazole derivatives, named tetroazolemycins A (1) and B (2), have been isolated from the acetone extract of the mycelium of Streptomyces olivaceus FXJ8.012 derived from deep-sea water, together with three known compounds, spoxazomicins A–C (35), isolated from the fermentation supernatant. The planar structure and relative configuration of tetroazolemycins were elucidated by a combination of spectroscopic analyses, including 1D- and 2D-NMR techniques, and showed to be new pyochelin-type antibiotics. Both compounds showed metal ion-binding activity and their Zn2+ complexes exhibited weak activity against pathogenic bacteria Klebsiella pneumoniae. Full article
(This article belongs to the Special Issue Deep-Sea Natural Products)
Open AccessArticle Synthesis, Characterization, and Antibacterial Activity of Cross-Linked Chitosan-Glutaraldehyde
Mar. Drugs 2013, 11(5), 1534-1552; doi:10.3390/md11051534
Received: 18 February 2013 / Revised: 17 April 2013 / Accepted: 26 April 2013 / Published: 13 May 2013
Cited by 22 | PDF Full-text (1054 KB) | HTML Full-text | XML Full-text
Abstract
This present study deals with synthesis, characterization and antibacterial activity of cross-linked chitosan-glutaraldehyde. Results from this study indicated that cross-linked chitosan-glutaraldehyde markedly inhibited the growth of antibiotic-resistant Burkholderia cepacia complex regardless of bacterial species and incubation time while bacterial growth was unaffected [...] Read more.
This present study deals with synthesis, characterization and antibacterial activity of cross-linked chitosan-glutaraldehyde. Results from this study indicated that cross-linked chitosan-glutaraldehyde markedly inhibited the growth of antibiotic-resistant Burkholderia cepacia complex regardless of bacterial species and incubation time while bacterial growth was unaffected by solid chitosan. Furthermore, high temperature treated cross-linked chitosan-glutaraldehyde showed strong antibacterial activity against the selected strain 0901 although the inhibitory effects varied with different temperatures. In addition, physical-chemical and structural characterization revealed that the cross-linking of chitosan with glutaraldehyde resulted in a rougher surface morphology, a characteristic Fourier transform infrared (FTIR) band at 1559 cm−1, a specific X-ray diffraction peak centered at 2θ = 15°, a lower contents of carbon, hydrogen and nitrogen, and a higher stability of glucose units compared to chitosan based on scanning electron microscopic observation, FTIR spectra, X-ray diffraction pattern, as well as elemental and thermo gravimetric analysis. Overall, this study indicated that cross-linked chitosan-glutaraldehyde is promising to be developed as a new antibacterial drug. Full article
Open AccessArticle Spasmolytic Effect of Caulerpine Involves Blockade of Ca2+ Influx on Guinea Pig Ileum
Mar. Drugs 2013, 11(5), 1553-1564; doi:10.3390/md11051553
Received: 25 February 2013 / Revised: 16 April 2013 / Accepted: 26 April 2013 / Published: 13 May 2013
Cited by 6 | PDF Full-text (477 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In this work, we investigated the spasmolytic effect of caulerpine, a bisindole alkaloid isolated from marine algae of the Caulerpa genus, on guinea pig ileum. Our findings indicated that caulerpine inhibited phasic contractions induced by carbachol (IC50 = 7.0 ± 1.9 [...] Read more.
In this work, we investigated the spasmolytic effect of caulerpine, a bisindole alkaloid isolated from marine algae of the Caulerpa genus, on guinea pig ileum. Our findings indicated that caulerpine inhibited phasic contractions induced by carbachol (IC50 = 7.0 ± 1.9 × 10−5 M), histamine (IC50 = 1.3 ± 0.3 × 10−4 M) and serotonin (IC50 = 8.0 ± 1.4 × 10−5 M) in a non-selective manner. Furthermore, caulerpine concentration-dependently inhibited serotonin-induced cumulative contractions (pD′2 = 4.48 ± 0.08), shifting the curves to the right with Emax reduction and slope of 2.44 ± 0.21, suggesting a noncompetitive antagonism pseudo-irreversible. The alkaloid also relaxed the ileum pre-contracted by KCl (EC50 = 9.0 ± 0.9 × 10−5 M) and carbachol (EC50 = 4.6 ± 0.7 × 10−5 M) in a concentration-dependent manner. This effect was probably due to inhibition of Ca2+ influx through voltage-gated calcium channels (CaV), since caulerpine slightly inhibited the CaCl2-induced contractions in depolarizing medium without Ca2+, shifting the curves to the right and with Emax reduction. According to these results, the spasmolytic effect of caulerpine on guinea pig ileum seems to involve inhibition of Ca2+ influx through CaV. However, other mechanisms are not discarded. Full article
(This article belongs to the Special Issue Marine Algae)
Open AccessArticle Chemistry and Tumor Cell Growth Inhibitory Activity of 11,20-Epoxy-3Z,5(6)E-diene Briaranes from the South China Sea Gorgonian Dichotella gemmacea
Mar. Drugs 2013, 11(5), 1565-1582; doi:10.3390/md11051565
Received: 1 March 2013 / Revised: 7 April 2013 / Accepted: 11 April 2013 / Published: 15 May 2013
Cited by 9 | PDF Full-text (802 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Eighteen new 11,20-epoxy-3Z,5E-dien briaranes, gemmacolides AA–AR (118), were isolated together with three known analogs, dichotellides F (19) and I (20), and juncenolide C (21), from [...] Read more.
Eighteen new 11,20-epoxy-3Z,5E-dien briaranes, gemmacolides AA–AR (118), were isolated together with three known analogs, dichotellides F (19) and I (20), and juncenolide C (21), from the South China Sea gorgonian Dichotella gemmacea. The structures of the compounds were elucidated by detailed spectroscopic analysis and comparison with reported data. The absolute configuration was determined based on the ECD experiment. In the in vitro bioassay, compounds 13, 5, 6, 812, and 1419 exhibited different levels of growth inhibition activity against A549 and MG63 cell lines. Preliminary structure-activity analysis suggests that 12-O-isovalerate may increase the activity whereas 13- or 14-O-isovalerate may decrease the activity. Contribution of substitutions at C-2 and C-16 remains uncertain. Full article
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Open AccessArticle Influence of Environmental Factors on the Paralytic Shellfish Toxin Content and Profile of Alexandrium catenella (Dinophyceae) Isolated from the Mediterranean Sea
Mar. Drugs 2013, 11(5), 1583-1601; doi:10.3390/md11051583
Received: 4 March 2013 / Revised: 27 March 2013 / Accepted: 28 March 2013 / Published: 15 May 2013
Cited by 5 | PDF Full-text (1097 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Laboratory experiments were designed to study the toxin content and profile of the Alexandrium catenella strain ACT03 (isolated from Thau Lagoon, French Mediterranean) in response to abiotic environmental factors under nutrient-replete conditions. This dinoflagellate can produce various paralytic shellfish toxins with concentrations [...] Read more.
Laboratory experiments were designed to study the toxin content and profile of the Alexandrium catenella strain ACT03 (isolated from Thau Lagoon, French Mediterranean) in response to abiotic environmental factors under nutrient-replete conditions. This dinoflagellate can produce various paralytic shellfish toxins with concentrations ranging from 2.9 to 50.3 fmol/cell. The toxin profile was characterized by carbamate toxins (GTX3, GTX4 and GTX5) and N-sulfocarbamoyl toxins (C1, C2, C3 and C4). C2 dominated at 12–18 °C, but only for salinities ranging from 10 to 25 psu, whereas GTX5 became dominant at temperatures ranging from 21 to 30 °C at almost all salinities. There was no significant variation in the cellular toxin amount from 18 °C to 27 °C for salinities ranging between 30 and 40 psu. At salinities of 10 to 25 psu, the toxin concentrations always remained below 20 fmol/cell. Toxin content was stable for irradiance ranging from 10 to 70 μmol photons/m2/s then slightly increased. Overall, the toxin profile was more stable than the toxin content (fmol/cell), except for temperature and/or salinity values different from those recorded during Alexandrium blooms in Thau Lagoon. Full article
(This article belongs to the Special Issue Marine Neurotoxins)
Open AccessArticle Response Surface Methodology for Ultrasound-Assisted Extraction of Astaxanthin from Haematococcus pluvialis
Mar. Drugs 2013, 11(5), 1644-1655; doi:10.3390/md11051644
Received: 29 March 2013 / Revised: 26 April 2013 / Accepted: 8 May 2013 / Published: 21 May 2013
Cited by 17 | PDF Full-text (718 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Astaxanthin is a novel carotenoid nutraceutical occurring in many crustaceans and red yeasts. It has exhibited various biological activities including prevention or amelioration of cardiovascular disease, gastric ulcer, hypertension, and diabetic nephropathy. In this study, ultrasound-assisted extraction was developed for the effective [...] Read more.
Astaxanthin is a novel carotenoid nutraceutical occurring in many crustaceans and red yeasts. It has exhibited various biological activities including prevention or amelioration of cardiovascular disease, gastric ulcer, hypertension, and diabetic nephropathy. In this study, ultrasound-assisted extraction was developed for the effective extraction of astaxanthin from Haematococcus pluvialis. Some parameters such as extraction solvent, liquid-to-solid ratio, extraction temperature, and extraction time were optimized by single-factor experiment and response surface methodology. The optimal extraction conditions were 48.0% ethanol in ethyl acetate, the liquid-to-solid ratio was 20:1 (mL/g), and extraction for 16.0 min at 41.1 °C under ultrasound irradiation of 200 W. Under optimal conditions, the yield of astaxanthin was 27.58 ± 0.40 mg/g. The results obtained are beneficial for the full utilization of Haematococcus pluvialis, which also indicated that ultrasound-assisted extraction is a very useful method for extracting astaxanthin from marine life. Full article
Open AccessArticle Outbreak of Diarrhetic Shellfish Poisoning Associated with Mussels, British Columbia, Canada
Mar. Drugs 2013, 11(5), 1669-1676; doi:10.3390/md11051669
Received: 12 March 2013 / Revised: 5 April 2013 / Accepted: 19 April 2013 / Published: 21 May 2013
Cited by 16 | PDF Full-text (660 KB) | HTML Full-text | XML Full-text
Abstract
In 2011, a Diarrhetic Shellfish Poisoning (DSP) outbreak occurred in British Columbia (BC), Canada that was associated with cooked mussel consumption. This is the first reported DSP outbreak in BC. Investigation of ill individuals, traceback of product and laboratory testing for toxins [...] Read more.
In 2011, a Diarrhetic Shellfish Poisoning (DSP) outbreak occurred in British Columbia (BC), Canada that was associated with cooked mussel consumption. This is the first reported DSP outbreak in BC. Investigation of ill individuals, traceback of product and laboratory testing for toxins were used in this investigation. Sixty-two illnesses were reported. Public health and food safety investigation identified a common food source and harvest area. Public health and regulatory agencies took actions to recall product and notify the public. Shellfish monitoring program changes were implemented after the outbreak. Improved response and understanding of toxin production will improve management of future DSP outbreaks. Full article
Open AccessArticle c-Jun N-Terminal Kinase Phosphorylation Is a Biomarker of Plitidepsin Activity
Mar. Drugs 2013, 11(5), 1677-1692; doi:10.3390/md11051677
Received: 27 February 2013 / Revised: 1 April 2013 / Accepted: 18 April 2013 / Published: 21 May 2013
Cited by 2 | PDF Full-text (780 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Plitidepsin is an antitumor drug of marine origin currently in Phase III clinical trials in multiple myeloma. In cultured cells, plitidepsin induces cell cycle arrest or an acute apoptotic process in which sustained activation of c-Jun N-terminal kinase (JNK) plays a [...] Read more.
Plitidepsin is an antitumor drug of marine origin currently in Phase III clinical trials in multiple myeloma. In cultured cells, plitidepsin induces cell cycle arrest or an acute apoptotic process in which sustained activation of c-Jun N-terminal kinase (JNK) plays a crucial role. With a view to optimizing clinical use of plitidepsin, we have therefore evaluated the possibility of using JNK activation as an in vivo biomarker of response. In this study, we show that administration of a single plitidepsin dose to mice xenografted with human cancer cells does indeed lead to increased phosphorylation of JNK in tumors at 4 to 12 h. By contrast, no changes were found in other in vitro plitidepsin targets such as the levels of phosphorylated-ERK, -p38MAPK or the protein p27KIP1. Interestingly, plitidepsin also increased JNK phosphorylation in spleens from xenografted mice showing similar kinetics to those seen in tumors, thereby suggesting that normal tissues might be useful for predicting drug activity. Furthermore, plitidepsin administration to rats at plasma concentrations comparable to those achievable in patients also increased JNK phosphorylation in peripheral mononuclear blood cells. These findings suggest that changes in JNK activity provide a reliable biomarker for plitidepsin activity and this could be useful for designing clinical trials and maximizing the efficacy of plitidepsin. Full article
Open AccessArticle Polyketides from a Marine-Derived Fungus Xylariaceae sp.
Mar. Drugs 2013, 11(5), 1718-1727; doi:10.3390/md11051718
Received: 19 March 2013 / Revised: 22 April 2013 / Accepted: 25 April 2013 / Published: 21 May 2013
Cited by 11 | PDF Full-text (257 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Eighteen polyketides (118) including six citrinin derivatives, two phenol derivatives, one cyclopentenone, two naphthol derivatives, and seven tetralone derivatives were isolated from the culture broth of a marine-derived fungal strain Xylariaceae sp. SCSGAF0086. Five of these compounds ( [...] Read more.
Eighteen polyketides (118) including six citrinin derivatives, two phenol derivatives, one cyclopentenone, two naphthol derivatives, and seven tetralone derivatives were isolated from the culture broth of a marine-derived fungal strain Xylariaceae sp. SCSGAF0086. Five of these compounds (1, 2, 8, 9, and 10) were new, and their structures were determined by spectroscopic methods. Compounds 4, 6, 7, and 17 showed enzyme-inhibitory activities towards several tested enzymes, and 6 and 7 showed strong antifouling activity against Bugula neritina larvae settlement. This is the first time that the antifouling and enzyme-inhibitory activities of these compounds has been reported. Full article
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Open AccessArticle Extract from the Zooxanthellate Jellyfish Cotylorhiza tuberculata Modulates Gap Junction Intercellular Communication in Human Cell Cultures
Mar. Drugs 2013, 11(5), 1728-1762; doi:10.3390/md11051728
Received: 28 March 2013 / Revised: 24 April 2013 / Accepted: 25 April 2013 / Published: 22 May 2013
Cited by 7 | PDF Full-text (2058 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
On a global scale, jellyfish populations in coastal marine ecosystems exhibit increasing trends of abundance. High-density outbreaks may directly or indirectly affect human economical and recreational activities, as well as public health. As the interest in biology of marine jellyfish grows, a [...] Read more.
On a global scale, jellyfish populations in coastal marine ecosystems exhibit increasing trends of abundance. High-density outbreaks may directly or indirectly affect human economical and recreational activities, as well as public health. As the interest in biology of marine jellyfish grows, a number of jellyfish metabolites with healthy potential, such as anticancer or antioxidant activities, is increasingly reported. In this study, the Mediterranean “fried egg jellyfish” Cotylorhiza tuberculata (Macri, 1778) has been targeted in the search forputative valuable bioactive compounds. A medusa extract was obtained, fractionated, characterized by HPLC, GC-MS and SDS-PAGE and assayed for its biological activity on breast cancer cells (MCF-7) and human epidermal keratinocytes (HEKa). The composition of the jellyfish extract included photosynthetic pigments, valuable ω-3 and ω-6 fatty acids, and polypeptides derived either from jellyfish tissues and their algal symbionts. Extract fractions showed antioxidant activity and the ability to affect cell viability and intercellular communication mediated by gap junctions (GJIC) differentially in MCF-7and HEKa cells. A significantly higher cytotoxicity and GJIC enhancement in MCF-7 compared to HEKa cells was recorded. A putative action mechanism for the anticancer bioactivity through the modulation of GJIC has been hypothesized and its nutraceutical and pharmaceutical potential was discussed. Full article
(This article belongs to the collection Bioactive Compounds from Marine Plankton)

Review

Jump to: Research, Other

Open AccessReview Meroterpenes from Marine Invertebrates: Structures, Occurrence, and Ecological Implications
Mar. Drugs 2013, 11(5), 1602-1643; doi:10.3390/md11051602
Received: 19 March 2013 / Revised: 7 April 2013 / Accepted: 7 May 2013 / Published: 17 May 2013
Cited by 14 | PDF Full-text (3645 KB) | HTML Full-text | XML Full-text
Abstract
Meroterpenes are widely distributed among marine organisms; they are particularly abundant within brown algae, but other important sources include microorganisms and invertebrates. In the present review the structures and bioactivities of meroterpenes from marine invertebrates, mainly sponges and tunicates, are summarized. More [...] Read more.
Meroterpenes are widely distributed among marine organisms; they are particularly abundant within brown algae, but other important sources include microorganisms and invertebrates. In the present review the structures and bioactivities of meroterpenes from marine invertebrates, mainly sponges and tunicates, are summarized. More than 300 molecules, often complex and with unique skeletons originating from intra- and inter-molecular cyclizations, and/or rearrangements, are illustrated. The reported syntheses are mentioned. The issue of a potential microbial link to their biosynthesis is also shortly outlined. Full article
(This article belongs to the Special Issue Marine Secondary Metabolites)
Open AccessReview Use of Okadaic Acid to Identify Relevant Phosphoepitopes in Pathology: A Focus on Neurodegeneration
Mar. Drugs 2013, 11(5), 1656-1668; doi:10.3390/md11051656
Received: 18 March 2013 / Revised: 2 April 2013 / Accepted: 16 April 2013 / Published: 21 May 2013
Cited by 4 | PDF Full-text (328 KB) | HTML Full-text | XML Full-text
Abstract
Protein phosphorylation is involved in the regulation of a wide variety of physiological processes and is the result of a balance between protein kinase and phosphatase activities. Biologically active marine derived compounds have been shown to represent an interesting source of novel [...] Read more.
Protein phosphorylation is involved in the regulation of a wide variety of physiological processes and is the result of a balance between protein kinase and phosphatase activities. Biologically active marine derived compounds have been shown to represent an interesting source of novel compounds that could modify that balance. Among them, the marine toxin and tumor promoter, okadaic acid (OA), has been shown as an inhibitor of two of the main cytosolic, broad-specificity protein phosphatases, PP1 and PP2A, thus providing an excellent cell-permeable probe for examining the role of protein phosphorylation, and PP1 and PP2A in particular, in any physiological or pathological process. In the present work, we review the use of okadaic acid to identify specific phosphoepitopes mainly in proteins relevant for neurodegeneration. We will specifically highlight those cases of highly dynamic phosphorylation-dephosphorylation events and the ability of OA to block the high turnover phosphorylation, thus allowing the detection of modified residues that could be otherwise difficult to identify. Finally, its effect on tau hyperhosphorylation and its relevance in neurodegenerative pathologies such as Alzheimer’s disease and related dementia will be discussed. Full article
(This article belongs to the Special Issue Okadaic Acid and Dinophysis Toxins)
Open AccessReview “Head-to-Side-Chain” Cyclodepsipeptides of Marine Origin
Mar. Drugs 2013, 11(5), 1693-1717; doi:10.3390/md11051693
Received: 12 March 2013 / Revised: 7 April 2013 / Accepted: 23 April 2013 / Published: 21 May 2013
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Abstract
Since the late 1980s, a large number of depsipeptides that contain a new topography, referred to as “head-to-side-chain” cyclodepsipeptides, have been isolated and characterized. These peptides present a unique structural arrangement that comprises a macrocyclic region closed through an ester bond between [...] Read more.
Since the late 1980s, a large number of depsipeptides that contain a new topography, referred to as “head-to-side-chain” cyclodepsipeptides, have been isolated and characterized. These peptides present a unique structural arrangement that comprises a macrocyclic region closed through an ester bond between the C-terminus and a β-hydroxyl group, and terminated with a polyketide moiety or a more simple branched aliphatic acid. This structural pattern, the presence of unique and complex residues, and relevant bioactivity are the main features shared by all the members of this new class of depsipeptides, which are reviewed herein. Full article
(This article belongs to the Special Issue Marine Peptides and Their Mimetics)
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Open AccessCorrection Correction: Kim, G.-Y. et al. Pectenotoxin-2 from Marine Sponges: A Potential Anti-Cancer Agent—A Review. Mar. Drugs 2011, 9, 2176-2187
Mar. Drugs 2013, 11(5), 1490-1491; doi:10.3390/md11051490
Received: 15 March 2013 / Accepted: 3 May 2013 / Published: 7 May 2013
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Abstract It has been brought to our attention that the Figure 1 (page 2177) in our published paper [1] has some errors, we would like to change it to the following one: [...] Full article

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