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Mar. Drugs, Volume 9, Issue 12 (December 2011), Pages 2488-2817

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Research

Jump to: Review

Open AccessArticle Chitosan, the Marine Functional Food, Is a Potent Adsorbent of Humic Acid
Mar. Drugs 2011, 9(12), 2488-2498; doi:10.3390/md9122488
Received: 18 October 2011 / Revised: 3 November 2011 / Accepted: 3 November 2011 / Published: 28 November 2011
Cited by 10 | PDF Full-text (213 KB) | HTML Full-text | XML Full-text
Abstract
Chitosan is prepared by the deacetylation of chitin, the second-most abundant biopolymer in nature, and has applicability in the removal of dyes, heavy metals and radioactive waste for pollution control. In weight-reduction remedies, chitosan is used to form hydrogels with lipids and to
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Chitosan is prepared by the deacetylation of chitin, the second-most abundant biopolymer in nature, and has applicability in the removal of dyes, heavy metals and radioactive waste for pollution control. In weight-reduction remedies, chitosan is used to form hydrogels with lipids and to depress the intestinal absorption of lipids. In this study, an experimental method was implemented to simulate the effect of chitosan on the adsorption of humic acid in the gastrointestinal tract. The adsorption capacity of chitosan was measured by its adsorption isotherm and analyzed using the Langmuir equation. The results showed that 3.3 grams of humic acid was absorbed by 1 gram of chitosan. The adsorption capacity of chitosan was much greater than that of chitin, diethylaminoethyl-cellulose or activated charcoal. Cellulose and carboxymethyl-cellulose, a cellulose derivative with a negative charge, could not adsorb humic acid in the gastrointestinal tract. This result suggests that chitosan entraps humic acid because of its positive charge. Full article
(This article belongs to the Special Issue Marine Functional Food)
Open AccessArticle Relevant Spatial Scales of Chemical Variation in Aplysina aerophoba
Mar. Drugs 2011, 9(12), 2499-2513; doi:10.3390/md9122499
Received: 11 October 2011 / Revised: 14 November 2011 / Accepted: 16 November 2011 / Published: 28 November 2011
Cited by 11 | PDF Full-text (469 KB) | HTML Full-text | XML Full-text
Abstract
Understanding the scale at which natural products vary the most is critical because it sheds light on the type of factors that regulate their production. The sponge Aplysina aerophoba is a common Mediterranean sponge inhabiting shallow waters in the Mediterranean and its area
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Understanding the scale at which natural products vary the most is critical because it sheds light on the type of factors that regulate their production. The sponge Aplysina aerophoba is a common Mediterranean sponge inhabiting shallow waters in the Mediterranean and its area of influence in Atlantic Ocean. This species contains large concentrations of brominated alkaloids (BAs) that play a number of ecological roles in nature. Our research investigates the ecological variation in BAs of A. aerophoba from a scale of hundred of meters to thousand kilometers. We used a nested design to sample sponges from two geographically distinct regions (Canary Islands and Mediterranean, over 2500 km), with two zones within each region (less than 50 km), two locations within each zone (less than 5 km), and two sites within each location (less than 500 m). We used high-performance liquid chromatography to quantify multiple BAs and a spectrophotometer to quantify chlorophyll a (Chl a). Our results show a striking degree of variation in both natural products and Chl a content. Significant variation in Chl a content occurred at the largest and smallest geographic scales. The variation patterns of BAs also occurred at the largest and smallest scales, but varied depending on which BA was analyzed. Concentrations of Chl a and isofistularin-3 were negatively correlated, suggesting that symbionts may impact the concentration of some of these compounds. Our results underline the complex control of the production of secondary metabolites, with factors acting at both small and large geographic scales affecting the production of multiple secondary metabolites. Full article
(This article belongs to the Special Issue Bioactive Compounds from Marine Sponges)
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Open AccessArticle Tetrahydrofuran Cembranoids from the Cultured Soft Coral Lobophytum crassum
Mar. Drugs 2011, 9(12), 2526-2536; doi:10.3390/md9122526
Received: 9 November 2011 / Revised: 25 November 2011 / Accepted: 28 November 2011 / Published: 7 December 2011
Cited by 14 | PDF Full-text (890 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Three new cembranoids, culobophylins A–C (13), along with two known compounds (4 and 5) were isolated from the cultured soft coral Lobophytum crassum. The structures of these compounds were elucidated on the basis of their spectroscopic
[...] Read more.
Three new cembranoids, culobophylins A–C (13), along with two known compounds (4 and 5) were isolated from the cultured soft coral Lobophytum crassum. The structures of these compounds were elucidated on the basis of their spectroscopic data and comparison of the NMR data with those of known analogues. Among these metabolites, 2 is rarely found in cembranoids possessing an isopropyl moiety with an epoxide group. Compound 1 exhibited significant cytotoxic activity against HL60 and DLD-1 cancer cell lines. Full article
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Open AccessArticle Inhibition of Virulence Gene Expression in Staphylococcus aureus by Novel Depsipeptides from a Marine Photobacterium
Mar. Drugs 2011, 9(12), 2537-2552; doi:10.3390/md9122537
Received: 22 September 2011 / Revised: 22 November 2011 / Accepted: 30 November 2011 / Published: 7 December 2011
Cited by 41 | PDF Full-text (2518 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
During a global research expedition, more than five hundred marine bacterial strains capable of inhibiting the growth of pathogenic bacteria were collected. The purpose of the present study was to determine if these marine bacteria are also a source of compounds that interfere
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During a global research expedition, more than five hundred marine bacterial strains capable of inhibiting the growth of pathogenic bacteria were collected. The purpose of the present study was to determine if these marine bacteria are also a source of compounds that interfere with the agr quorum sensing system that controls virulence gene expression in Staphylococcus aureus. Using a gene reporter fusion bioassay, we recorded agr interference as enhanced expression of spa, encoding Protein A, concomitantly with reduced expression of hla, encoding α-hemolysin, and rnaIII encoding RNAIII, the effector molecule of agr. A marine Photobacterium produced compounds interfering with agr in S. aureus strain 8325-4, and bioassay-guided fractionation of crude extracts led to the isolation of two novel cyclodepsipeptides, designated solonamide A and B. Northern blot analysis confirmed the agr interfering activity of pure solonamides in both S. aureus strain 8325-4 and the highly virulent, community-acquired strain USA300 (CA-MRSA). To our knowledge, this is the first report of inhibitors of the agr system by a marine bacterium. Full article
(This article belongs to the Special Issue Marine Anti-infective Agents)
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Open AccessArticle A Kinetic Study of Accumulation and Elimination of Microcystin-LR in Yellow Perch (Perca Flavescens) Tissue and Implications for Human Fish Consumption
Mar. Drugs 2011, 9(12), 2553-2571; doi:10.3390/md9122553
Received: 20 September 2011 / Revised: 15 November 2011 / Accepted: 2 December 2011 / Published: 8 December 2011
Cited by 5 | PDF Full-text (232 KB) | HTML Full-text | XML Full-text
Abstract
Fish consumption is a potential route of human exposure to the hepatotoxic microcystins, especially in lakes and reservoirs that routinely experience significant toxic Microcystis blooms. Understanding the rates of uptake and elimination for microcystins as well as the transfer efficiency into tissues of
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Fish consumption is a potential route of human exposure to the hepatotoxic microcystins, especially in lakes and reservoirs that routinely experience significant toxic Microcystis blooms. Understanding the rates of uptake and elimination for microcystins as well as the transfer efficiency into tissues of consumers are important for determining the potential for microcystins to be transferred up the food web and for predicting potential human health impacts. The main objective of this work was to conduct laboratory experiments to investigate the kinetics of toxin accumulation in fish tissue. An oral route of exposure was employed in this study, in which juvenile yellow perch (Perca flavescens) were given a single oral dose of 5 or 20 μg of microcystin-LR (MC-LR) via food and accumulation in the muscle, liver, and tank water were measured over 24 h. Peak concentrations of the water soluble fraction of microcystin were generally observed 8–10 h after dosing in the liver and after 12–16 h in the muscle, with a rapid decline in both tissues by 24 h. Up to 99% of the total recoverable (i.e., unbound) microcystin was measured in the tank water by 16 h after exposure. The relatively rapid uptake and elimination of the unbound fraction of microcystin in the liver and muscle of juvenile yellow perch within 24 h of exposure indicates that fish consumption may not be a major route of human exposure to microcystin, particularly in the Great Lakes. Full article
(This article belongs to the Special Issue Algal Toxins)
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Open AccessArticle Fucose-Containing Sulfated Polysaccharides from Brown Seaweeds Inhibit Proliferation of Melanoma Cells and Induce Apoptosis by Activation of Caspase-3 in Vitro
Mar. Drugs 2011, 9(12), 2605-2621; doi:10.3390/md9122605
Received: 11 October 2011 / Revised: 21 November 2011 / Accepted: 6 December 2011 / Published: 13 December 2011
Cited by 28 | PDF Full-text (980 KB) | HTML Full-text | XML Full-text
Abstract
Fucose-containing sulfated polysaccharides (FCSPs) extracted from seaweeds, especially brown macro-algae, are known to possess essential bioactive properties, notably growth inhibitory effects on tumor cells. In this work, we conducted a series of in vitro studies to examine the influence of FCSPs products from
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Fucose-containing sulfated polysaccharides (FCSPs) extracted from seaweeds, especially brown macro-algae, are known to possess essential bioactive properties, notably growth inhibitory effects on tumor cells. In this work, we conducted a series of in vitro studies to examine the influence of FCSPs products from Sargassum henslowianum C. Agardh (FSAR) and Fucus vesiculosus (FVES), respectively, on proliferation of melanoma B16 cells and to investigate the underlying apoptosis promoting mechanisms. Cell viability analysis showed that both FCSPs products, i.e., FSAR and FVES, decreased the proliferation of the melanoma cells in a dose-response fashion, with FSAR being more potent at lower dosages, and FVES being relatively more anti-proliferative than FSAR at higher dosages. Flow cytometric analysis by Annexin V staining of the melanoma cells exposed to the FCSPs products confirmed that both FSAR and FVES induced apoptosis. The FCSPs-induced apoptosis was evidenced by loss of plasma membrane asymmetry and translocation of the cell membrane phospholipids and was accompanied by the activation of caspase-3. The FCSPs bioactivity is proposed to be attributable to distinct structural features of the FCSPs, particularly the presence of sulfated galactofucans (notably in S. henslowianum) and sulfated fucans (notably in F. vesiculosus). This study thus indicates that unfractionated FCSPs may exert bioactive effects on skin cancer cells via induction of apoptosis through cascades of reactions that involve activation of caspase-3. Full article
Open AccessArticle An Investigation into the Cytotoxic Effects of 13-Acetoxysarcocrassolide from the Soft Coral Sarcophyton crassocaule on Bladder Cancer Cells
Mar. Drugs 2011, 9(12), 2622-2642; doi:10.3390/md9122622
Received: 23 October 2011 / Revised: 18 November 2011 / Accepted: 30 November 2011 / Published: 13 December 2011
Cited by 14 | PDF Full-text (1546 KB) | HTML Full-text | XML Full-text
Abstract
Active compounds from natural products have been widely studied. The anti-tumor effects of 13-acetoxysarcocrassolide isolated from Formosan soft coral Sarcophyton crassocaule on bladder cancer cells were examined in this study. An MTT assay showed that 13-acetoxysarcocrassolide was cytotoxic to bladder female transitional cancer
[...] Read more.
Active compounds from natural products have been widely studied. The anti-tumor effects of 13-acetoxysarcocrassolide isolated from Formosan soft coral Sarcophyton crassocaule on bladder cancer cells were examined in this study. An MTT assay showed that 13-acetoxysarcocrassolide was cytotoxic to bladder female transitional cancer (BFTC) cells. We determined that the BFTC cells underwent cell death through apoptosis by flow cytometry. Due to the highly-migratory nature of the BFTC cells, the ability of 13-acetoxysarcocrassolide to stop their migration was assessed by a wound healing assay. To determine which proteins were affected in the BFTC cells upon treatment, a comparative proteomic analysis was performed. By LC-MS/MS analysis, we identified that 19 proteins were up-regulated and eight were down-regulated. Seven of the proteins were confirmed by western blotting analysis. This study reveals clues to the potential mechanism of the cytotoxic effects of 13-acetoxysarcocrassolide on BFTC cells. Moreover, it suggests that PPT1 and hnRNP F could be new biomarkers for bladder cancer. The results of this study are also helpful for the diagnosis, progression monitoring and therapeutic strategies of transitional cell tumors. Full article
Open AccessArticle Cembranoids from the Dongsha Atoll Soft Coral Lobophytum crassum
Mar. Drugs 2011, 9(12), 2705-2716; doi:10.3390/md9122705
Received: 3 November 2011 / Revised: 5 December 2011 / Accepted: 9 December 2011 / Published: 15 December 2011
Cited by 17 | PDF Full-text (1073 KB) | HTML Full-text | XML Full-text
Abstract
Chemical investigation of the Dongsha Atoll soft coral Lobophytum crassum has afforded four new cembranoids, crassumols A–C (13) and 13-acetoxysarcophytoxide (4). The structures of these isolated compounds were elucidated by extensive NMR and HRESIMS experiments. The cytotoxicity
[...] Read more.
Chemical investigation of the Dongsha Atoll soft coral Lobophytum crassum has afforded four new cembranoids, crassumols A–C (13) and 13-acetoxysarcophytoxide (4). The structures of these isolated compounds were elucidated by extensive NMR and HRESIMS experiments. The cytotoxicity and anti-HCMV (Human cytomegalovirus) activities of 14 were evaluated in vitro. Compound 4 exhibited cytotoxicity against A-549 (human lung carcinoma) cell line with an ED50 of 3.6 μg/mL. Full article
Open AccessArticle Tetrodotoxin-Bupivacaine-Epinephrine Combinations for Prolonged Local Anesthesia
Mar. Drugs 2011, 9(12), 2717-2728; doi:10.3390/md9122717
Received: 9 October 2011 / Revised: 18 November 2011 / Accepted: 21 November 2011 / Published: 15 December 2011
Cited by 12 | PDF Full-text (329 KB) | HTML Full-text | XML Full-text
Abstract
Currently available local anesthetics have analgesic durations in humans generally less than 12 hours. Prolonged-duration local anesthetics will be useful for postoperative analgesia. Previous studies showed that in rats, combinations of tetrodotoxin (TTX) with bupivacaine had supra-additive effects on sciatic block durations. In
[...] Read more.
Currently available local anesthetics have analgesic durations in humans generally less than 12 hours. Prolonged-duration local anesthetics will be useful for postoperative analgesia. Previous studies showed that in rats, combinations of tetrodotoxin (TTX) with bupivacaine had supra-additive effects on sciatic block durations. In those studies, epinephrine combined with TTX prolonged blocks more than 10-fold, while reducing systemic toxicity. TTX, formulated as Tectin, is in phase III clinical trials as an injectable systemic analgesic for chronic cancer pain. Here, we examine dose-duration relationships and sciatic nerve histology following local nerve blocks with combinations of Tectin with bupivacaine 0.25% (2.5 mg/mL) solutions, with or without epinephrine 5 µg/mL (1:200,000) in rats. Percutaneous sciatic blockade was performed in Sprague-Dawley rats, and intensity and duration of sensory blockade was tested blindly with different Tectin-bupivacaine-epinephrine combinations. Between-group comparisons were analyzed using ANOVA and post-hoc Sidak tests. Nerves were examined blindly for signs of injury. Blocks containing bupivacaine 0.25% with Tectin 10 µM and epinephrine 5 µg/mL were prolonged by roughly 3-fold compared to blocks with bupivacaine 0.25% plain (P < 0.001) or bupivacaine 0.25% with epinephrine 5 µg/mL (P < 0.001). Nerve histology was benign for all groups. Combinations of Tectin in bupivacaine 0.25% with epinephrine 5 µg/mL appear promising for prolonged duration of local anesthesia. Full article
(This article belongs to the Special Issue Tetrodotoxin)
Open AccessArticle Inhibitory Effects of Ecklonia cava Extract on High Glucose-Induced Hepatic Stellate Cell Activation
Mar. Drugs 2011, 9(12), 2793-2808; doi:10.3390/md9122793
Received: 10 November 2011 / Revised: 9 December 2011 / Accepted: 13 December 2011 / Published: 20 December 2011
Cited by 11 | PDF Full-text (336 KB) | HTML Full-text | XML Full-text
Abstract
Nonalcoholic steatohepatitis (NASH) is a disease closely associated with obesity and diabetes. A prevalence of type 2 diabetes and a high body mass index in cryptogenic cirrhosis may imply that obesity leads to cirrhosis. Here, we examined the effects of an extract of
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Nonalcoholic steatohepatitis (NASH) is a disease closely associated with obesity and diabetes. A prevalence of type 2 diabetes and a high body mass index in cryptogenic cirrhosis may imply that obesity leads to cirrhosis. Here, we examined the effects of an extract of Ecklonia cava, a brown algae, on the activation of high glucose-induced hepatic stellate cells (HSCs), key players in hepatic fibrosis. Isolated HSCs were incubated with or without a high glucose concentration. Ecklonia cava extract (ECE) was added to the culture simultaneously with the high glucose. Treatment with high glucose stimulated expression of type I collagen and α-smooth muscle actin, which are markers of activation in HSCs, in a dose-dependent manner. The activation of high glucose-treated HSCs was suppressed by the ECE. An increase in the formation of intracellular reactive oxygen species (ROS) and a decrease in intracellular glutathione levels were observed soon after treatment with high glucose, and these changes were suppressed by the simultaneous addition of ECE. High glucose levels stimulated the secretion of bioactive transforming growth factor-β (TGF-β) from the cells, and the stimulation was also suppressed by treating the HSCs with ECE. These results suggest that the suppression of high glucose-induced HSC activation by ECE is mediated through the inhibition of ROS and/or GSH and the downregulation of TGF-β secretion. ECE is useful for preventing the development of diabetic liver fibrosis. Full article
(This article belongs to the Special Issue Marine Functional Food)
Open AccessArticle Aurantoside J: a New Tetramic Acid Glycoside from Theonella swinhoei. Insights into the Antifungal Potential of Aurantosides
Mar. Drugs 2011, 9(12), 2809-2817; doi:10.3390/md9122809
Received: 3 November 2011 / Revised: 7 December 2011 / Accepted: 15 December 2011 / Published: 20 December 2011
Cited by 10 | PDF Full-text (195 KB) | HTML Full-text | XML Full-text
Abstract
The chemical investigation of an Indonesian specimen of Theonella swinhoei afforded four aurantosides, one of which, aurantoside J (5), is a new compound. The structure of this metabolite, exhibiting the unprecedented N-α-glycosidic linkage between the pentose and the tetramate units, has been
[...] Read more.
The chemical investigation of an Indonesian specimen of Theonella swinhoei afforded four aurantosides, one of which, aurantoside J (5), is a new compound. The structure of this metabolite, exhibiting the unprecedented N-α-glycosidic linkage between the pentose and the tetramate units, has been determined through detailed spectroscopic analysis. The four obtained aurantosides have been tested against five fungal strains (four Candida and one Fusarium) responsible of invasive infections in immuno-compromised patients. The non-cytotoxic aurantoside I (4) was the single compound to show an excellent potency against all the tested strains, thus providing valuable insights about the antifungal potential of this class of compounds and the structure-activity relationships. Full article
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Review

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Open AccessReview Seaweed Polysaccharides and Derived Oligosaccharides Stimulate Defense Responses and Protection Against Pathogens in Plants
Mar. Drugs 2011, 9(12), 2514-2525; doi:10.3390/md9122514
Received: 8 September 2011 / Revised: 17 November 2011 / Accepted: 18 November 2011 / Published: 29 November 2011
Cited by 56 | PDF Full-text (297 KB) | HTML Full-text | XML Full-text
Abstract
Plants interact with the environment by sensing “non-self” molecules called elicitors derived from pathogens or other sources. These molecules bind to specific receptors located in the plasma membrane and trigger defense responses leading to protection against pathogens. In particular, it has been shown
[...] Read more.
Plants interact with the environment by sensing “non-self” molecules called elicitors derived from pathogens or other sources. These molecules bind to specific receptors located in the plasma membrane and trigger defense responses leading to protection against pathogens. In particular, it has been shown that cell wall and storage polysaccharides from green, brown and red seaweeds (marine macroalgae) corresponding to ulvans, alginates, fucans, laminarin and carrageenans can trigger defense responses in plants enhancing protection against pathogens. In addition, oligosaccharides obtained by depolymerization of seaweed polysaccharides also induce protection against viral, fungal and bacterial infections in plants. In particular, most seaweed polysaccharides and derived oligosaccharides trigger an initial oxidative burst at local level and the activation of salicylic (SA), jasmonic acid (JA) and/or ethylene signaling pathways at systemic level. The activation of these signaling pathways leads to an increased expression of genes encoding: (i) Pathogenesis-Related (PR) proteins with antifungal and antibacterial activities; (ii) defense enzymes such as pheylalanine ammonia lyase (PAL) and lipoxygenase (LOX) which determine accumulation of phenylpropanoid compounds (PPCs) and oxylipins with antiviral, antifugal and antibacterial activities and iii) enzymes involved in synthesis of terpenes, terpenoids and/or alkaloids having antimicrobial activities. Thus, seaweed polysaccharides and their derived oligosaccharides induced the accumulation of proteins and compounds with antimicrobial activities that determine, at least in part, the enhanced protection against pathogens in plants. Full article
(This article belongs to the Special Issue Marine Anti-infective Agents)
Open AccessReview Marine Polysaccharides in Microencapsulation and Application to Aquaculture: “From Sea to Sea”
Mar. Drugs 2011, 9(12), 2572-2604; doi:10.3390/md9122572
Received: 10 October 2011 / Revised: 18 November 2011 / Accepted: 22 November 2011 / Published: 8 December 2011
Cited by 17 | PDF Full-text (852 KB) | HTML Full-text | XML Full-text
Abstract
This review’s main objective is to discuss some physico-chemical features of polysaccharides as intrinsic determinants for the supramolecular structures that can efficiently provide encapsulation of drugs and other biological entities. Thus, the general characteristics of some basic polysaccharides are outlined in terms of
[...] Read more.
This review’s main objective is to discuss some physico-chemical features of polysaccharides as intrinsic determinants for the supramolecular structures that can efficiently provide encapsulation of drugs and other biological entities. Thus, the general characteristics of some basic polysaccharides are outlined in terms of their conformational, dynamic and thermodynamic properties. The analysis of some polysaccharide gelling properties is also provided, including the peculiarity of the charged polysaccharides. Then, the way the basic physical chemistry of polymer self-assembly is made in practice through the laboratory methods is highlighted. A description of the several literature procedures used to influence molecular interactions into the macroscopic goal of the encapsulation is given with an attempt at classification. Finally, a practical case study of specific interest, the use of marine polysaccharide matrices for encapsulation of vaccines in aquaculture, is reported. Full article
(This article belongs to the collection Marine Polysaccharides)
Open AccessReview Natural Products from the Lithistida: A Review of the Literature since 2000
Mar. Drugs 2011, 9(12), 2643-2682; doi:10.3390/md9122643
Received: 27 September 2011 / Revised: 9 November 2011 / Accepted: 6 December 2011 / Published: 15 December 2011
Cited by 19 | PDF Full-text (3006 KB) | HTML Full-text | XML Full-text
Abstract
Lithistid sponges are known to produce a diverse array of compounds ranging from polyketides, cyclic and linear peptides, alkaloids, pigments, lipids, and sterols. A majority of these structurally complex compounds have very potent and interesting biological activities. It has been a decade since
[...] Read more.
Lithistid sponges are known to produce a diverse array of compounds ranging from polyketides, cyclic and linear peptides, alkaloids, pigments, lipids, and sterols. A majority of these structurally complex compounds have very potent and interesting biological activities. It has been a decade since a thorough review has been published that summarizes the literature on the natural products reported from this amazing sponge order. This review provides an update on the current taxonomic classification of the Lithistida, describes structures and biological activities of 131 new natural products, and discusses highlights from the total syntheses of 16 compounds from marine sponges of the Order Lithistida providing a compilation of the literature since the last review published in 2002. Full article
(This article belongs to the Special Issue Bioactive Compounds from Marine Sponges)
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Open AccessReview Tetrodotoxin as a Tool to Elucidate Sensory Transduction Mechanisms: The Case for the Arterial Chemoreceptors of the Carotid Body
Mar. Drugs 2011, 9(12), 2683-2704; doi:10.3390/md9122683
Received: 22 September 2011 / Revised: 22 November 2011 / Accepted: 1 December 2011 / Published: 15 December 2011
Cited by 2 | PDF Full-text (578 KB) | HTML Full-text | XML Full-text
Abstract
Carotid bodies (CBs) are secondary sensory receptors in which the sensing elements, chemoreceptor cells, are activated by decreases in arterial PO2 (hypoxic hypoxia). Upon activation, chemoreceptor cells (also known as Type I and glomus cells) increase their rate of release of neurotransmitters
[...] Read more.
Carotid bodies (CBs) are secondary sensory receptors in which the sensing elements, chemoreceptor cells, are activated by decreases in arterial PO2 (hypoxic hypoxia). Upon activation, chemoreceptor cells (also known as Type I and glomus cells) increase their rate of release of neurotransmitters that drive the sensory activity in the carotid sinus nerve (CSN) which ends in the brain stem where reflex responses are coordinated. When challenged with hypoxic hypoxia, the physiopathologically most relevant stimulus to the CBs, they are activated and initiate ventilatory and cardiocirculatory reflexes. Reflex increase in minute volume ventilation promotes CO2 removal from alveoli and a decrease in alveolar PCO2 ensues. Reduced alveolar PCO2 makes possible alveolar and arterial PO2 to increase minimizing the intensity of hypoxia. The ventilatory effect, in conjunction the cardiocirculatory components of the CB chemoreflex, tend to maintain an adequate supply of oxygen to the tissues. The CB has been the focus of attention since the discovery of its nature as a sensory organ by de Castro (1928) and the discovery of its function as the origin of ventilatory reflexes by Heymans group (1930). A great deal of effort has been focused on the study of the mechanisms involved in O2 detection. This review is devoted to this topic, mechanisms of oxygen sensing. Starting from a summary of the main theories evolving through the years, we will emphasize the nature and significance of the findings obtained with veratridine and tetrodotoxin (TTX) in the genesis of current models of O2-sensing. Full article
(This article belongs to the Special Issue Tetrodotoxin)
Open AccessReview Cyanotoxins: Bioaccumulation and Effects on Aquatic Animals
Mar. Drugs 2011, 9(12), 2729-2772; doi:10.3390/md9122729
Received: 18 October 2011 / Revised: 29 November 2011 / Accepted: 1 December 2011 / Published: 16 December 2011
Cited by 77 | PDF Full-text (393 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Cyanobacteria are photosynthetic prokaryotes with wide geographic distribution that can produce secondary metabolites named cyanotoxins. These toxins can be classified into three main types according to their mechanism of action in vertebrates: hepatotoxins, dermatotoxins and neurotoxins. Many studies on the effects of cyanobacteria
[...] Read more.
Cyanobacteria are photosynthetic prokaryotes with wide geographic distribution that can produce secondary metabolites named cyanotoxins. These toxins can be classified into three main types according to their mechanism of action in vertebrates: hepatotoxins, dermatotoxins and neurotoxins. Many studies on the effects of cyanobacteria and their toxins over a wide range of aquatic organisms, including invertebrates and vertebrates, have reported acute effects (e.g., reduction in survivorship, feeding inhibition, paralysis), chronic effects (e.g., reduction in growth and fecundity), biochemical alterations (e.g., activity of phosphatases, GST, AChE, proteases), and behavioral alterations. Research has also focused on the potential for bioaccumulation and transferring of these toxins through the food chain. Although the herbivorous zooplankton is hypothesized as the main target of cyanotoxins, there is not unquestionable evidence of the deleterious effects of cyanobacteria and their toxins on these organisms. Also, the low toxin burden in secondary consumers points towards biodilution of microcystins in the food web as the predominant process. In this broad review we discuss important issues on bioaccumulation and the effects of cyanotoxins, with emphasis on microcystins, as well as drawbacks and future needs in this field of research. Full article
(This article belongs to the Special Issue Algal Toxins)
Open AccessReview Natural Product Chemistry of Gorgonian Corals of Genus Junceella—Part II
Mar. Drugs 2011, 9(12), 2773-2792; doi:10.3390/md9122773
Received: 10 November 2011 / Revised: 6 December 2011 / Accepted: 15 December 2011 / Published: 19 December 2011
Cited by 7 | PDF Full-text (1258 KB) | HTML Full-text | XML Full-text
Abstract
The structures, names, bioactivities, and references of 81 new secondary metabolites obtained from gorgonian corals belonging to the genus Junceella are described in this review. All compounds mentioned in this review were obtained from sea whip gorgonian corals Junceella fragilis and Junceella juncea
[...] Read more.
The structures, names, bioactivities, and references of 81 new secondary metabolites obtained from gorgonian corals belonging to the genus Junceella are described in this review. All compounds mentioned in this review were obtained from sea whip gorgonian corals Junceella fragilis and Junceella juncea, collected from the tropical and subtropical Indo-Pacific Ocean. Full article

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