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Mar. Drugs, Volume 8, Issue 8 (August 2010) – 11 articles , Pages 2223-2434

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Review
Pharmacological Analyses of Protein Kinases Regulating Egg Maturation in Marine Nemertean Worms: A Review and Comparison with Mammalian Eggs
Mar. Drugs 2010, 8(8), 2417-2434; https://doi.org/10.3390/md8082417 - 24 Aug 2010
Cited by 10 | Viewed by 5519
Abstract
For development to proceed normally, animal eggs must undergo a maturation process that ultimately depends on phosphorylations of key regulatory proteins. To analyze the kinases that mediate these phosphorylations, eggs of marine nemertean worms have been treated with pharmacological modulators of intracellular signaling [...] Read more.
For development to proceed normally, animal eggs must undergo a maturation process that ultimately depends on phosphorylations of key regulatory proteins. To analyze the kinases that mediate these phosphorylations, eggs of marine nemertean worms have been treated with pharmacological modulators of intracellular signaling pathways and subsequently probed with immunoblots employing phospho-specific antibodies. This article both reviews such analyses and compares them with those conducted on mammals, while focusing on how egg maturation in nemerteans is affected by signaling pathways involving cAMP, mitogen-activated protein kinases, Src-family kinases, protein kinase C isotypes, AMP-activated kinase, and the Cdc2 kinase of maturation-promoting factor. Full article
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Review
New One-Pot Methodologies for the Modification or Synthesis of Alkaloid Scaffolds
Mar. Drugs 2010, 8(8), 2395-2416; https://doi.org/10.3390/md8082395 - 24 Aug 2010
Cited by 24 | Viewed by 8341
Abstract
There are several avenues by which promising bioactive natural products can be produced in sufficient quantities to enable lead optimization and medicinal chemistry studies. The total synthesis of natural products is an important, but sometimes difficult, approach and requires the development of innovative [...] Read more.
There are several avenues by which promising bioactive natural products can be produced in sufficient quantities to enable lead optimization and medicinal chemistry studies. The total synthesis of natural products is an important, but sometimes difficult, approach and requires the development of innovative synthetic methodologies to simplify the synthesis of complex molecules. Various classes of natural product alkaloids are both common and widely distributed in plants, bacteria, fungi, insects and marine organisms. This mini-review will discuss the scope, mechanistic insights and enantioselectivity aspects of selected examples of recently developed one-pot methods that have been published in 2009 for the synthesis of substituted piperidines, quinolizidines, pyrrolidines, hexahydropyrrolizines, octahydroindolizines and g-lactams. In addition, progress on the synthesis of b-carboline (manzamine) alkaloids will also be discussed. Full article
(This article belongs to the Special Issue Alkaloid Analogs)
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Article
Total Synthesis and Antimicrobial Activity of a Natural Cycloheptapeptide of Marine Origin
Mar. Drugs 2010, 8(8), 2384-2394; https://doi.org/10.3390/md8082384 - 19 Aug 2010
Cited by 29 | Viewed by 6511
Abstract
The present study deals with the first total synthesis of the proline-rich cyclopolypeptide stylisin 2 via a solution phase technique by coupling of the Boc-l-Pro-l-Ile-l-Pro-OH tripeptide unit with the l-Phe-l-Pro-l-Pro-l-Tyr-OMe tetrapeptide unit, followed by cyclization of the resulting linear heptapeptide fragment. The chemical [...] Read more.
The present study deals with the first total synthesis of the proline-rich cyclopolypeptide stylisin 2 via a solution phase technique by coupling of the Boc-l-Pro-l-Ile-l-Pro-OH tripeptide unit with the l-Phe-l-Pro-l-Pro-l-Tyr-OMe tetrapeptide unit, followed by cyclization of the resulting linear heptapeptide fragment. The chemical structure of the finally synthesized peptide was elucidated by FTIR, 1H/13C-NMR and FAB MS spectral data, as well as elemental analyses. The newly synthesized peptide was subjected to antimicrobial screening against eight pathogenic microbes and found to exhibit potent antimicrobial activity against Pseudomonas aeruginosa, Klebsiella pneumoniae and Candida albicans, in addition to moderate antidermatophyte activity against pathogenic Trichophyton mentagrophytes and Microsporum audouinii when compared to standard drugs—gatifloxacin and griseofulvin. Full article
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Article
Applications of Chemical Shift Imaging to Marine Sciences
Mar. Drugs 2010, 8(8), 2369-2383; https://doi.org/10.3390/md8082369 - 19 Aug 2010
Cited by 6 | Viewed by 7232
Abstract
The successful applications of magnetic resonance imaging (MRI) in medicine are mostly due to the non-invasive and non-destructive nature of MRI techniques. Longitudinal studies of humans and animals are easily accomplished, taking advantage of the fact that MRI does not use harmful radiation [...] Read more.
The successful applications of magnetic resonance imaging (MRI) in medicine are mostly due to the non-invasive and non-destructive nature of MRI techniques. Longitudinal studies of humans and animals are easily accomplished, taking advantage of the fact that MRI does not use harmful radiation that would be needed for plain film radiographic, computerized tomography (CT) or positron emission (PET) scans. Routine anatomic and functional studies using the strong signal from the most abundant magnetic nucleus, the proton, can also provide metabolic information when combined with in vivo magnetic resonance spectroscopy (MRS). MRS can be performed using either protons or hetero-nuclei (meaning any magnetic nuclei other than protons or 1H) including carbon (13C) or phosphorus (31P). In vivo MR spectra can be obtained from single region ofinterest (ROI or voxel) or multiple ROIs simultaneously using the technique typically called chemical shift imaging (CSI). Here we report applications of CSI to marine samples and describe a technique to study in vivo glycine metabolism in oysters using 13C MRS 12 h after immersion in a sea water chamber dosed with [2-13C]-glycine. This is the first report of 13C CSI in a marine organism. Full article
(This article belongs to the Special Issue Metabolomic Approaches to Marine Organisms)
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Review
Terpenes from Marine-Derived Fungi
Mar. Drugs 2010, 8(8), 2340-2368; https://doi.org/10.3390/md8082340 - 13 Aug 2010
Cited by 61 | Viewed by 8969
Abstract
Terpenes from marine-derived fungi show a pronounced degree of structural diversity, and due to their interesting biological and pharmacological properties many of them have aroused interest from synthetic chemists and the pharmaceutical industry alike. The aim of this paper is to give an [...] Read more.
Terpenes from marine-derived fungi show a pronounced degree of structural diversity, and due to their interesting biological and pharmacological properties many of them have aroused interest from synthetic chemists and the pharmaceutical industry alike. The aim of this paper is to give an overview of the structural diversity of terpenes from marine-derived fungi, highlighting individual examples of chemical structures and placing them in a context of other terpenes of fungal origin. Wherever possible, information regarding the biological activity is presented. Full article
(This article belongs to the Special Issue Terpenoids of Marine Origin)
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Article
Impact of Ocean Acidification on Energy Metabolism of Oyster, Crassostrea gigas—Changes in Metabolic Pathways and Thermal Response
Mar. Drugs 2010, 8(8), 2318-2339; https://doi.org/10.3390/md8082318 - 11 Aug 2010
Cited by 294 | Viewed by 13855
Abstract
Climate change with increasing temperature and ocean acidification (OA) poses risks for marine ecosystems. According to Pörtner and Farrell [1], synergistic effects of elevated temperature and CO2-induced OA on energy metabolism will narrow the thermal tolerance window of marine ectothermal animals. [...] Read more.
Climate change with increasing temperature and ocean acidification (OA) poses risks for marine ecosystems. According to Pörtner and Farrell [1], synergistic effects of elevated temperature and CO2-induced OA on energy metabolism will narrow the thermal tolerance window of marine ectothermal animals. To test this hypothesis, we investigated the effect of an acute temperature rise on energy metabolism of the oyster, Crassostrea gigas chronically exposed to elevated CO2 levels (partial pressure of CO2 in the seawater ~0.15 kPa, seawater pH ~ 7.7). Within one month of incubation at elevated PCO2 and 15 °C hemolymph pH fell (pHe = 7.1 ± 0.2 (CO2-group) vs. 7.6 ± 0.1 (control)) and PeCO2 values in hemolymph increased (0.5 ± 0.2 kPa (CO2-group) vs. 0.2 ± 0.04 kPa (control)). Slightly but significantly elevated bicarbonate concentrations in the hemolymph of CO2-incubated oysters ([HCO-3]e = 1.8 ± 0.3 mM (CO2-group) vs. 1.3 ± 0.1 mM (control)) indicate only minimal regulation of extracellular acid-base status. At the acclimation temperature of 15 °C the OA-induced decrease in pHe did not lead to metabolic depression in oysters as standard metabolism rates (SMR) of CO2-exposed oysters were similar to controls. Upon acute warming SMR rose in both groups, but displayed a stronger increase in the CO2-incubated group. Investigation in isolated gill cells revealed a similar temperature-dependence of respiration between groups. Furthermore, the fraction of cellular energy demand for ion regulation via Na+/K+-ATPase was not affected by chronic hypercapnia or temperature. Metabolic profiling using 1H-NMR spectroscopy revealed substantial changes in some tissues following OA exposure at 15 °C. In mantle tissue alanine and ATP levels decreased significantly whereas an increase in succinate levels was observed in gill tissue. These findings suggest shifts in metabolic pathways following OA-exposure. Our study confirms that OA affects energy metabolism in oysters and suggests that climate change may affect populations of sessile coastal invertebrates such as mollusks. Full article
(This article belongs to the Special Issue Metabolomic Approaches to Marine Organisms)
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Review
Halogenated Compounds from Marine Algae
Mar. Drugs 2010, 8(8), 2301-2317; https://doi.org/10.3390/md8082301 - 09 Aug 2010
Cited by 172 | Viewed by 12863
Abstract
Marine algae produce a cocktail of halogenated metabolites with potential commercial value. Structures exhibited by these compounds go from acyclic entities with a linear chain to complex polycyclic molecules. Their medical and pharmaceutical application has been investigated for a few decades, however other [...] Read more.
Marine algae produce a cocktail of halogenated metabolites with potential commercial value. Structures exhibited by these compounds go from acyclic entities with a linear chain to complex polycyclic molecules. Their medical and pharmaceutical application has been investigated for a few decades, however other properties, such as antifouling, are not to be discarded. Many compounds were discovered in the last years, although the need for new drugs keeps this field open as many algal species are poorly screened. The ecological role of marine algal halogenated metabolites has somehow been overlooked. This new research field will provide valuable and novel insight into the marine ecosystem dynamics as well as a new approach to comprehending biodiversity. Furthermore, understanding interactions between halogenated compound production by algae and the environment, including anthropogenic or global climate changes, is a challenging target for the coming years. Research of halogenated metabolites has been more focused on macroalgae than on phytoplankton. However, phytoplankton could be a very promising material since it is the base of the marine food chain with quick adaptation to environmental changes, which undoubtedly has consequences on secondary metabolism. This paper reviews recent progress on this field and presents trends on the role of marine algae as producers of halogenated compounds. Full article
(This article belongs to the Special Issue Bioactive Halogenated Metabolites of Marine Origin)
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Review
An Update on the Therapeutic Role of Alkylglycerols
Mar. Drugs 2010, 8(8), 2267-2300; https://doi.org/10.3390/md8082267 - 05 Aug 2010
Cited by 67 | Viewed by 8005
Abstract
Scandinavian folk medicine used shark liver oil for the treatment of cancers and other ailments based on the rarity of tumors in sharks and their ability to resist infections. Shark liver oil is a source of alkylglycerols which have been studied as anti-cancer [...] Read more.
Scandinavian folk medicine used shark liver oil for the treatment of cancers and other ailments based on the rarity of tumors in sharks and their ability to resist infections. Shark liver oil is a source of alkylglycerols which have been studied as anti-cancer agents in several clinical trials. Moreover, alkylglycerols have been investigated for the treatment of radiation induced side effects and for their ability to boost the immune system. Several experimental studies have shown the ability of alkylglycerols to open the blood brain barrier to facilitate the access of therapeutic drugs to the central nervous system. This review covers the most important studies of alkylglycerols in both animals and humans. Full article
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Review
Chitosan Composites for Bone Tissue Engineering—An Overview
Mar. Drugs 2010, 8(8), 2252-2266; https://doi.org/10.3390/md8082252 - 02 Aug 2010
Cited by 482 | Viewed by 15615
Abstract
Bone contains considerable amounts of minerals and proteins. Hydroxyapatite [Ca10(PO4)6(OH)2] is one of the most stable forms of calcium phosphate and it occurs in bones as major component (60 to 65%), along with other [...] Read more.
Bone contains considerable amounts of minerals and proteins. Hydroxyapatite [Ca10(PO4)6(OH)2] is one of the most stable forms of calcium phosphate and it occurs in bones as major component (60 to 65%), along with other materials including collagen, chondroitin sulfate, keratin sulfate and lipids. In recent years, significant progress has been made in organ transplantation, surgical reconstruction and the use of artificial protheses to treat the loss or failure of an organ or bone tissue. Chitosan has played a major role in bone tissue engineering over the last two decades, being a natural polymer obtained from chitin, which forms a major component of crustacean exoskeleton. In recent years, considerable attention has been given to chitosan composite materials and their applications in the field of bone tissue engineering due to its minimal foreign body reactions, an intrinsic antibacterial nature, biocompatibility, biodegradability, and the ability to be molded into various geometries and forms such as porous structures, suitable for cell ingrowth and osteoconduction. The composite of chitosan including hydroxyapatite is very popular because of the biodegradability and biocompatibility in nature. Recently, grafted chitosan natural polymer with carbon nanotubes has been incorporated to increase the mechanical strength of these composites. Chitosan composites are thus emerging as potential materials for artificial bone and bone regeneration in tissue engineering. Herein, the preparation, mechanical properties, chemical interactions and in vitro activity of chitosan composites for bone tissue engineering will be discussed. Full article
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Article
Characterization of the Exopolysaccharide Produced by Salipiger mucosus A3T, a Halophilic Species Belonging to the Alphaproteobacteria, Isolated on the Spanish Mediterranean Seaboard
Mar. Drugs 2010, 8(8), 2240-2251; https://doi.org/10.3390/md8082240 - 30 Jul 2010
Cited by 48 | Viewed by 9082
Abstract
We have studied the exopolysaccharide produced by the type strain of Salipiger mucosus, a species of halophilic, EPS-producing (exopolysaccharide-producing) bacterium belonging to the Alphaproteobacteria. The strain, isolated on the Mediterranean seaboard, produced a polysaccharide, mainly during its exponential growth phase but [...] Read more.
We have studied the exopolysaccharide produced by the type strain of Salipiger mucosus, a species of halophilic, EPS-producing (exopolysaccharide-producing) bacterium belonging to the Alphaproteobacteria. The strain, isolated on the Mediterranean seaboard, produced a polysaccharide, mainly during its exponential growth phase but also to a lesser extent during the stationary phase. Culture parameters influenced bacterial growth and EPS production. Yield was always directly related to the quantity of biomass in the culture. The polymer is a heteropolysaccharide with a molecular mass of 250 kDa and its components are glucose (19.7%, w/w), mannose (34%, w/w), galactose (32.9%, w/w) and fucose (13.4%, w/w). Fucose and fucose-rich oligosaccharides have applications in the fields of medicine and cosmetics. The chemical or enzymatic hydrolysis of fucose-rich polysaccharides offers a new efficient way to process fucose. The exopolysaccharide in question produces a solution of very low viscosity that shows pseudoplastic behavior and emulsifying activity on several hydrophobic substrates. It also has a high capacity for binding cations and incorporating considerable quantities of sulfates, this latter feature being very unusual in bacterial polysaccharides. Full article
(This article belongs to the Collection Marine Polysaccharides)
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Article
In-Depth Analysis of Exoproteomes from Marine Bacteria by Shotgun Liquid Chromatography-Tandem Mass Spectrometry: the Ruegeria pomeroyi DSS-3 Case-Study
Mar. Drugs 2010, 8(8), 2223-2239; https://doi.org/10.3390/md8082223 - 29 Jul 2010
Cited by 40 | Viewed by 8314
Abstract
Microorganisms secrete into their extracellular environment numerous compounds that are required for their survival. Many of these compounds could be of great interest for biotechnology applications and their genes used in synthetic biology design. The secreted proteins and the components of the translocation [...] Read more.
Microorganisms secrete into their extracellular environment numerous compounds that are required for their survival. Many of these compounds could be of great interest for biotechnology applications and their genes used in synthetic biology design. The secreted proteins and the components of the translocation systems themselves can be scrutinized in-depth by the most recent proteomic tools. While the secretomes of pathogens are well-documented, those of non-pathogens remain largely to be established. Here, we present the analysis of the exoproteome from the marine bacterium Ruegeria pomeroyi DSS-3 grown in standard laboratory conditions. We used a shotgun approach consisting of trypsin digestion of the exoproteome, and identification of the resulting peptides by liquid chromatography coupled to tandem mass spectrometry. Three different proteins that have domains homologous to those observed in RTX toxins were uncovered and were semi-quantified as the most abundantly secreted proteins. One of these proteins clearly stands out from the catalogue, representing over half of the total exoproteome. We also listed many soluble proteins related to ABC and TRAP transporters implied in the uptake of nutrients. The Ruegeria pomeroyi DSS-3 case-study illustrates the power of the shotgun nano-LC-MS/MS strategy to decipher the exoproteome from marine bacteria and to contribute to environmental proteomics. Full article
(This article belongs to the Special Issue Marine Peptides)
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