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The medicinal potential of promising marine organisms: A review
Abstract
In the sea, there are many resources and novel chemical entities with biological activities that may be useful for finding drugs with greater efficacy and specificity to treat a variety of human diseases. Although there are some reports on promising natural products to date, the technology on small-molecule-based methods to isolate protein sets using a proteomic approach, which is currently useful for pharmaceuticals, is lacking. The separation of proteins from marine organisms, especially calcifying marine organisms, which are part of one of the most biologically diverse and ecologically important ecosystems on the planet, is difficult due to contamination by skeletal tissues and the high sensitivity of tissues to handling. Here, I highlight some recent studies of marine organisms, paying particular attention to their discovery, medicinal activities, and mechanisms of action. In addition, I discuss an effective protocol from sample preparation to protein purification for proteomic analysis to isolate candidate proteins for target identification, helping turn the current wealth of proteomic information into drug discovery and optimization. This information might be useful for medicinal chemists, biologists and biotechnologists for further studies utilizing the great resources of these promising marine organisms.
... For example, some of these proteins with human physiological activity can help accelerate lab-based bone morphogenesis and increase bone volumes with efficacies equivalent to currently used recombinant proteins [1]. Proteins with potential for bone repair and drug discovery, extracted either from naturally occurring skeletal organic matrices or derived from cultivated tissues, can be identified and isolated using chromatography, cell assays and proteomic methods [1,9,11]. Proteomics is a high-throughput analytical method for rapidly identifying known or unknown proteins in complex mixtures [5]. If purification methods can be established for skeletal proteins derived from calcifying marine organisms, researchers in the emerging fields of proteomics and medicinal chemistry could utilize these methods for subsequent drug discovery and, as a more specific example, bone repair. ...
... Pharmaceutical industries now accept the world's oceans as a major frontier for medical research. The emergence of this relatively new area of scientific exploration has been of enormous interest to the popular and scientific press, and several review publications have appeared on the topic [1,9,11]. In the review presented here, we focus on recent progress in the discovery and production of new marine skeletal proteins and polysaccharides of pharmaceutical interest. ...
In recent years, the medicinal potential of marine organisms has attracted increasing attention. This is due to their immense diversity and adaptation to unique ecological niches that has led to vast physiological and biochemical diversification. Among these organisms, marine calcifiers are an abundant source of novel proteins and chemical entities that can be used for drug discovery. Studies of the skeletal organic matrix proteins of marine calcifiers have focused on biomedical applications such as the identification of growth inducing proteins that can be used for bone regeneration, for example, 2/4 bone morphogenic proteins (BMP). Although a few reports on the functions of proteins derived from marine calcifiers can be found in the literature, marine calcifiers themselves remain an untapped source of proteins for the development of innovative pharmaceuticals. Following an overview of the current knowledge of skeletal organic matrix proteins from marine calcifiers, this review will focus on various aspects of marine skeletal protein research including sources, biosynthesis, structures, and possible strategies for chemical or physical modification. Special attention will be given to potential medical applications and recent discoveries of skeletal proteins and polysaccharides with biologically appealing characteristics. In addition, I will introduce an effective protocol for sample preparation and protein purification that includes isolation technology for biopolymers (of both soluble and insoluble organic matrices) from coralline algae. These algae are a widespread but poorly studied group of shallow marine calcifiers that have great potential for marine drug discovery.
... There are some techniques that have been established in purifying collagens from the invertebrates; however, a proteomic approach might be a useful tool to learn more about the collagen and its functions in detail. Proteomics have already been established as an important tool for the detection, characterization, and analysis of pharmaceutically useful proteins from marine organisms, and this approach provides the most precise evaluation of protein identities, abundance, composition, and protein expression profiling [5,26,[88][89][90]. Therefore, in regard to collagen, the proteomics approach could be a promising toolkit in the near future. ...
The extraction and purification of collagen are of great interest due to its biological function and medicinal applications. Although marine invertebrates are abundant in the animal kingdom, our knowledge of their extracellular matrix (ECM), which mainly contains collagen, is lacking. The functions of collagen isolated from marine invertebrates remain an untouched source of the proteinaceous component in the development of groundbreaking pharmaceuticals. This review will give an overview of currently used collagens and their future applications, as well as the methodological issues of collagens from marine invertebrates for potential drug discovery.
A bioassay guided approach was used to isolate two antitumor tetrahydroisoquinoline alkaloids, 3 and 4, from the marine ascidian Ecteinascidia turbinata. The structures of 3 and 4 were determined through spectroscopic methods
In the Peru upwelling area, total amino acids account for 20-30% of the POC flux and 40-65% of the PON flux. Relative decomposition rates were different for the three types of amino acids distinguished and may be higher at night than during the day. The rates, sites and mechanisms of diagenetic reactions are discussed as well as their implications for benthic metabolism. About 80% of the amino acids produced in the surface waters during primary production are decomposed above 14m, and c.10% of the primary production is decomposed as particulate amino acids between 14-50m, up to 12% possibly reaching the sea floor. -from Authors
Soft corals contain small spicules of calcium carbonate called “sclerites”, which are biomineralized structures composed of an organic matrix and a mineral fraction. Since informations concerning the structure of sclerites, their crystallization properties and mineral composition are scarce, we have studied these parameters in the alcyonarian, Sinularia polydactyla. In the first step, we have determined the structure and shape of the sclerites. Then, we have identified the polymorphs of calcium carbonate both by X-ray diffraction (XRD) and Raman microprobe analysis. A mineral phase in the sclerites was identified as calcite, as revealed by the calcite (1 0 4) reflection. An electron probe microanalyzer was used to analyze the element on the sclerite. This analysis indicates that the sclerite has both Ca and Mg bearing calcite, in which Mg showed a relatively high concentration (5–10 mol%). Analysis of proteinaceous components of calcified sclerites reveals the significance of protein composition to calcification. The function of matrix proteins during bio-calcification was studied by simulating the nucleation and growth of calcium carbonates in vitro. After precipitation of CaCO3 in the experimental design, the obtained crystals were characterized by scanning electron microscope (SEM) and XRD. The matrix proteins, which were purified from the calcified sclerites, can control the morphology of CaCO3 crystals and are potentially involved in the process of bio-calcification.
The cell walls of diatoms consist of a silica frustule encased in an organic coating. Biochemical characterization of this coating should allow insight into: (1) the mechanism of silicification; (2) taxonomy and evolution of diatoms; (3) preservation of fossil frustules. The amino acid and sugar composition of cell walls from 6 diatom species have been elucidated. When compared to cellular protein, cell-wall protein is enriched in serine plus threonine and glycine, and depleted in acidic, sulfur-containing and aromatic amino acids. The sugars of the cell-wall carbohydrates are quite variable and fucose tends to replace glucose in estuarine species. Condensation of silicic acid, in epitaxial order, on a protein template enriched in serine and threonine, is suggested as the Si-depositing mechanism in diatoms. The nature of this template and the polysaccharides in the cell wall may determine the solubility of diatom frustules in various environments. There is sufficient variability in cell-wall amino acids to warrant further investigation of their taxonomic utility. The sugars appear to be related to environmental factors, but they may also serve in biosystematic studies.
Over the past decade, sinking particulate organic matter (POM) samples from depth profiles in the equatorial Pacific have been analyzed by multiple techniques to evaluate the organic matter preservation mechanisms most dominant in the oceanic water column. How the samples were analyzed strongly influenced which organic matter preservation scheme appeared to dominate. Bulk functional group analysis by solid-state 13C-NMR showed that organic matter composition varied very little in light of the extreme degree of remineralization (>98%) that occurred with water column depth. This indicates preservation by a physical mechanism, such as sorption to mineral grains or protection within a mineral aggregate. However, detailed lipid studies of the characterizable fraction showed that selective preservation was important, with lipid structure being correlated with preservation over depth. However, the characterizable fraction decreases greatly with depth. Therefore, in this paper, direct temperature-resolved mass spectrometry (DT-MS), was used to further characterize POM, with the assumption that this approach could “see” a substantial proportion of the “uncharacterized” organic matter. DT-MS, which provides compositional information at an intermediate level between the detailed wet chemical studies and one-dimensional solid-state C13-NMR, also indicates an intermediate view between the mechanistic extremes of selective preservation and physical protection.
Calcium carbonate exists in two main forms, calcite and aragonite, in the skeletons of marine organisms. The primary mineralogy of marine carbonates has changed over the history of the earth depending on the magnesium/calcium ratio in seawater during the periods of the so-called "calcite and aragonite seas." Organisms that prefer certain mineralogy appear to flourish when their preferred mineralogy is favored by seawater chemistry. However, this rule is not without exceptions. For example, some octocorals produce calcite despite living in an aragonite sea. Here, we address the unresolved question of how organisms such as soft corals are able to form calcitic skeletal elements in an aragonite sea. We show that an extracellular protein called ECMP-67 isolated from soft coral sclerites induces calcite formation in vitro even when the composition of the calcifying solution favors aragonite precipitation. Structural details of both the surface and the interior of single crystals generated upon interaction with ECMP-67 were analyzed with an apertureless-type near-field IR microscope with high spatial resolution. The results show that this protein is the main determining factor for driving the production of calcite instead of aragonite in the biocalcification process and that -OH, secondary structures (e.g. α-helices and amides), and other necessary chemical groups are distributed over the center of the calcite crystals. Using an atomic force microscope, we also explored how this extracellular protein significantly affects the molecular-scale kinetics of crystal formation. We anticipate that a more thorough investigation of the proteinaceous skeleton content of different calcite-producing marine organisms will reveal similar components that determine the mineralogy of the organisms. These findings have significant implications for future models of the crystal structure of calcite in nature.
The minerals involved in the formation of metazoan skeletons principally comprise glassy silica, calcium phosphate or carbonate. Because of their ancient heritage, glass sponges (Hexactinellida) may shed light on fundamental questions such as molecular evolution, the unique chemistry and formation of the first skeletal silica-based structures, and the origin of multicellular animals. We have studied anchoring spicules from the metre-long stalk of the glass rope sponge (Hyalonema sieboldi; Porifera, Class Hexactinellida), which are remarkable for their size, durability, flexibility and optical properties. Using slow-alkali etching of biosilica, we isolated the organic fraction, which was revealed to be dominated by a hydroxylated fibrillar collagen that contains an unusual [Gly-3Hyp-4Hyp] motif. We speculate that this motif is predisposed for silica precipitation, and provides a novel template for biosilicification in nature.
Previous investigations, focused primarily on vertebrates, have noted substantial losses of eggs and embryos to predators and questioned why selection has not more commonly resulted in the evolution of chemically defended eggs or embryos. Hypotheses regarding the apparent rarity of such defenses have emphasized the potential incompatibility of actively developing tissues and toxic metabolites. Alternatively, this apparent pattern could be an artifact of our greater knowledge of vertebrates, which in general show few tendencies for synthesizing defensive metabolites in either juvenile or adult stages. In this study, we investigated adult and larval chemical defenses of a group of benthic marine invertebrates, the ascidians, in which the adults are often chemically rich, and we contrast our findings with what is known about chemical defenses of eggs and embryos from terrestrial and aquatic organisms. Our findings suggest that there is no fundamental incompatibility of rapidly developing juvenile tissues and bioactive metabolites, and that chemically defended eggs and larval stages may be common among some taxonomic groups. Ascidians are benthic invertebrates that often lack apparent physical defenses against predation, yet are common on coral reefs where predation by fishes is intense. In contrast to most co—occurring invertebrates, many ascidians also release large, conspicuous larvae during daylight hours when exposure to fish predation would be highest. Thus selection by predators might favor the evolution of distasteful larvae. In situ observations indicate that many conspicuous ascidian larvae are distasteful to potential consumers. We investigated the ability of secondary metabolites produced by taxonomically diverse ascidians from geographically distant locales to deter predation on both adults and larvae. Larvae from the Caribbean ascidian Trididemnum solidum were distasteful to reef fishes, and when organic extracts of individual larvae were transferred onto eyes of freeze—dried krill (a good larval mimic in terms of size and color), these eyes were rejected by fishes while control eyes (solvent only) were readily eaten. Larvae of the Indo—Pacific ascidian Sigillina cf. signifera were also distasteful to coral—reef fishes and contained the unpalatable bipyrrole alkaloid tambjamine C. When added to artificial foods at or below their natural mean concentrations and offered to consumers in field and laboratory feeding assays, the secondary metabolites produced by Trididemnum solidum (Caribbean Sea), Sigillina cf. signifera (Indo—Pacific), and Polyandrocarpa sp. (Gulf of California) significantly deterred feeding by co—occurring fishes and invertebrates. Secondary metabolites produced by Trididemnum cf. cyanophorum from the Caribbean Sea, Lissoclinum patella from the Indo—Pacific, and Aplidium californicum from the temperate Pacific, and the small stellate spicules common to many tropical didemnid ascidians did not significantly affect fish feeding. High—pressure liquid chromatography (HPLC) analyses of six didemnin cyclic peptides in individual colonies of Trididemnum solidum from one patch reef at Little San Salvador, Bahamas found large inter—colony differences in their concentrations. The mean concentration of didemnin B was more than double the concentration needed to significantly deter fish feeding in our field assays, and feeding tests with nordidemnin B showed that it deterred fish feeding across the entire range of natural concentrations. HPLC analysis of the extract from a combined collection of T. solidum larvae found adequate concentrations of didemnin B and nordidemnin B to account for their rejection by foraging fishes. We demonstrate that taxonomically diverse ascidians from habitats characterized by intense predation pressure produce secondary metabolites that significantly reduce predation on both adults and larvae, and suggest that this defensive chemistry may be crucial in allowing the release of large, well—provisioned larvae during daylight periods when larvae have the greatest probability of using photic cues to select physically appropriate settlement sites. Production of defensive secondary metabolites appears widespread among certain groups of ascidians, some of which are also known to concentrate acid and heavy metals as additional defensive strategies. DOI: 10.2307/2937316 © Ecological Society of America
Acidic proteins are generally thought to control mineral formation and growth in biocalcification. Analysis of proteinaceous components in the soluble and insoluble matrix fractions of sclerites in Sinularia polydactyla indicates that aspartic acid composes about 60% of the insoluble and 29% of the soluble matrix fractions. We previously analyzed aspartic acids in the matrix fractions (insoluble = 17 mol%; soluble = 38 mol%) of sclerites from a different type of soft coral, Lobophytum crassum, which showed comparatively lower aspartic acid-rich proteins than S. polydactyla. Thus, characterization of highly acidic proteins in the organic matrix of present species is an important first step toward linking function to individual proteins in soft coral. Here, we show that aspartic-acid rich proteins can control the CaCO(3) polymorph in vitro. The CaCO(3) precipitates in vitro in the presence of aspartic acid-rich proteins and 50 mM Mg(2+) was verified by Raman microprobe analysis. The matrix proteins of sclerites demonstrated that the aspartic-acid rich domain is crucial for the calcite precipitation in soft corals. The crystalline form of CaCO(3) in the presence of aspartic acid-rich proteins in vitro was identified by X-ray diffraction and, revealed calcitic polymorphisms with a strong (104) reflection. The structure of soft coral organic matrices containing aspartate-rich proteins and polysaccharides was assessed by Fourier transform infrared spectroscopy. These results strongly suggest that the aspartic acid-rich proteins within the organic matrix of soft corals play a key role in biomineralization regulation.
The protein-induced chemical structure in calcified organisms is an important factor contributing to their growth, but until now no direct evidence has been reported. Hence, we demonstrate a new analytical technique that combines an FTIR spectrometer and an apertureless-type near-field microscope with high spatial resolution. The complete structural composition of the biomineralized structure of marine organisms has been measured using this technique. The results show that -OH is distributed over the center of the mineral phase of small calcite, which was formed from interactions of matrix proteins.
The polymerase chain reaction (PCR) assay technologies evolved from a black box reaction with endpoint detection of the PCR products using gel electrophoresis to a quantitative PCR reaction with real-time detection of the products using fluorescent dyes. Current challenges are sample preparation, appropriate PCR controls, and interpretation of positive results. PCR systems with a validation certificate are available, with most having a convenient format and user-friendly software, thus facilitating their implementation in diagnostic and public health laboratories. Application of PCR in food microbiology is continuously broadened, for example in the detection of toxins, enumeration of bacterial and viral pathogens, characterization and typing of isolates, and measurement of gene expression.
In addition to the previously reported bioactive kahalalide F six new peptides are described. Six of these, including kahalalide F, are cyclic depsipeptides, ranging from a C-31 tripeptide to a C-75 tridecapeptide isolated from a sacoglossan mollusk, Elysia rufescens. The mollusk feeds on a green alga, Bryopsis sp., which has also been shown to elaborate some of these peptides in smaller yields, in addition to an acyclic analog of F, kahalalide G. The bioassay results of antitumor, antiviral, antimalarial, and OI (activity against AIDS opportunistic infections) tests are reported.
Ecteinascidins 729, 743, 745, 759A, 759B, and 770, tris(tetrahydroisoquinolines) with potent in vivo antitumor activity, have been isolated from the colonial tunicate Ecteinascidia turbinata, and their structures have been assigned
Bioassay guided fractionation of the ethyl acetate soluble fraction of the soft coral Lobophytum crassum yielded a cembranoid diterpene [(7E, 11E, 1R,2S,3R,4R,14S)-14-acetoxy-3,4-epoxycembra-7,11,15-triene-17,2-olide,1] as the potent anti-bacterial metabolite exhibiting activity against Pseudomonas aeroginosa, Staphylococcus epidermis, Staphylococcus aureus and Bacillus subtilis. A new ceramide (2) with moderate antibacterial activity besides two known polyhydroxysterols and batyl alcohol were also isolated.
This Microreview seeks to highlight the molecular diversity present in marine organisms, and illustrate by example some of the challenges encountered in exploring this resource. Marine natural products exhibit an impressive array of structural motifs, many of which are derived from biosynthetic pathways that are uniquely marine. Most importantly, some marine metabolites possess noteworthy biological activities, activities that have potential application outside marine ecosystems, such as antibiotics, antiparasitics, anticancer agents etc... The isolation, spectroscopic characterisation and assignment of stereostructures to these unusual metabolites is both challenging and rewarding. Examples featured in this Microreview follow a common theme in that they are all recent accounts of the isolation of natural products from Australian marine sponges, carried out in the laboratories of the author. In addition to presenting brief comments on specific structure elucidation strategies, an effort is made to emphasize techniques for solving stereochemical issues, as well as to speculate on the biosynthetic origins of some of these exotic marine natural products.
The structure of manoalide (), a new sesterterpenoid antibiotic isolated from a marine sponge, has been determined by spectral analysis and chemical transformations.
Organisms have been producing mineralized skeletons for the past
550
million years. They have evolved many different strategies for
improving
these materials at almost all hierarchical levels from
Ångstroms to
millimetres. Key components of biological materials are the
macromolecules, which are intimately involved in controlling
nucleation,
growth, shaping and adapting mechanical properties of the mineral
phase to
function. One interesting tendency that we have noted is that
organisms
have developed several strategies to produce materials that have
more
isotropic properties. Much can still be learned from studying the
principles of structure–function relations of biological
materials.
Some of this information may also provide new ideas for improved
design of
synthetic materials.
Two new diterpenoids, 2 and 4, having a dolabellane skeleton were isolated from the Okinawan soft coral of the genus Clavularia. Their structures were determined based on spectroscopic analysis, chemical conversion and X-ray crystallographic analysis. One of these diterpenoids showed cytotoxic activity against tumor cells.
This issue contains the following reviews:- "Highlights of marine natural products chemistry (1972-1999)", D. J. Faulkner; "Marine natural products", D. J. Faulkner; "Amaryllidaceae, muscarine, imidazole, oxazole, thiazole and peptide alkaloids, and other miscellaneous alkaloids", J. R. Lewis; "Lysine biosynthesis and metabolism in fungi", T. M. Zabriskie*, M. D. Jackson; "Iron chelators from mycobacteria (1954-1999) and potential therapeutic applications", A. F. Vergne*, A. J. Walz, M. J. Miller; and "Recent progress in the chemistry of the Stemona alkaloids", R. A. Pilli, M. da Conceicao Ferreira de Oliveira..
New antitumor polyether macrolides were successfully isolated from a marine sponge, Halichondria okadai Kadota. One of them, halichondrin B exhibited remarkable in vivo antitumor activity. Physiological properties and structures of these compounds are reported. The structures have been characterized by a long-straight carbon chain, a polyether macrolide, and a novel 2,6,9-trioxatricyclo left bracket 3. 3. 2. 0**3,**7 right bracket decane system which is the first example in natural products.
Eight new diterpene glycosides, pseudopterosins E-L (1-8), along with the methylated aglycon from pseudopterosin E (9), have been isolated from the organic extracts of two individual collections of the tropical Atlantic sea whip Pseudopterogorgia elisabethae. The aglycon portions of pseudopterosins E and F (1, 2) are identical with that of pseudopterosin A, but both metabolites have sugar moieties (α-L-fucose for pseudopterosin E and α-D-arabinose for pseudopterosin F) attached at the C-10 hydroxyl. Pseudopterosin G and its monoacetates (pseudopterosins H-J) are C-9 α-L-fucose glycosides. The diterpene aglycon of these molecules is a methyl epimer at the C-7 chiral center, in relation to the aglycons derived from pseudopterosins E and F. Pseudopterosins K and L (7, 8) are α-L-fucosides with the same diterpene skeleton as pseudopterosins E and F, but with the sugar attached at the C-9 hydroxyl. However, the aglycons of pseudopterosins K and L were found to be enantiomeric to those from pseudopterosins E and F (1, 2). The structure of pseudopterosin F was confirmed by X-ray crystallographic analysis, and the other new pseudopterosins were chemically converted to derivatives derived from pseudopterosin F. The new pseudopterosins are superior antiinflammatory agents in comparison to pseudopterosin A. Pseudopterosin E (1) shows very low acute toxicity in mice (LD50 > 300 mg/kg) and appears to act by a novel mechanism of pharmacological action.
Contignasterol (1), a highly oxygenated steroid with the ''unnatural'' 14-beta proton configuration and a cyclic hemiacetal functionality in its side chain, has been isolated from the marine sponge Petrosia contignata. The structure of contignasterol was elucidated via spectroscopic studies of its tetraacetate 2 and its reduction product pentaacetate 5. Contignasterol (1) is the first example of a naturally occurring steroid with the ''unnatural'' 14-beta proton configuration.
Bioactivities of 42 didemnin congeners, either isolated from the marine tunicates Trididemnun solidum and Aplidium albicans or prepared synthetically and semisynthetically, have been compared. The growth inhibition of various murine and human tumor cells and plaque reduction of HSV-1 and VSV grown on cultured mammalian cells were used to assess cytotoxicity and antiviral activity. Biochemical assays for macromolecular synthesis (protein, DNA, and RNA) and enzyme inhibition (dihydrofolate reductase, thymidylate synthase, DNA polymerase, RNA polymerase, and topoisomerases I and II) were also performed to specify the mechanisms of action of each analogue. Immunosuppressive activity of the didemnins was determined using a mixed lymphocyte reaction (MLR) assay. These assays revealed that the native cyclic depsipeptide core is an essential structural requirement for most of the bioactivites of the didemnins, especially for cytotoxicities and antiviral activities. The linear side-chain portion of the peptide can be altered with a gain, in some cases, of bioactivities. In particular, dehydrodidemnin B, tested against several types of tumor cells and in in vivo studies in mice, as well as didemnin M, tested for the mixed lymphocyte reaction and graft vs host reaction in murine systems, showed remarkable gains in their in vitro and in vivo activities compared to didemnin B.
A reproducible technique is described for extraction and quantitative analysis of neutral monosaccharides from a variety of solid natural sample types, requiring as little as 10 mg of total organic matter. Acid hydrolysis yields monomeric sugars which may exist in up to five isomeric forms when in solution. Lithium perchlorate is used to catalytically equilibrate sugar isomer mixtures in pyridine prior to conversion to their trimethylsilyl ether derivatives. Analysis is carried out by use of gas-HquM chromatography on fused-silica capillary columns. Quantification on the basis of a single clearly resolved peak for each sugar is made possible by the equilibration step. Sugar iosses and optimal conditions for maximum reproducible sugar recovery are determined for each extraction stage.
Ecteinascidins 729, 743 (I), 745, 759A, 759B, and 770, tris(tetrahydroisoquinolines) with potent in vivo antitumor activity, were isolated from the colonial tunicate E. turbinata. The structures were assigned on the basis of 2-dimensional homo- and heteronuclear NMR techniques, including heteronuclear multiple-bond correlation, and fast-atom-bombardment mass spectrometry (FABMS), esp. moving-belt liq. chromatog./FABMS, tandem FABMS/mass spectrometry, and high-resoln. neg.-ion FABMS
1.1. (+)-Aeroplysinin-1, a naturally occurring tyrosine metabolite from the marine sponge Verongia aerophoba, was found to inhibit the phosphorylation of lipocortin-like proteins by a highly purified preparation of the epidermal growth factor (EGF) receptor-tyrosine protein kinase complex from MCF-7 breast carcinoma cells.2.2. (+)-Aeroplysinin-1 blocked the EGF-dependent proliferation of both MCF-7 and ZR-75-1 human breast cancer cells and inhibited the ligand-induced endocytosis of the EGF receptor in vitro.3.3. Treatment with aeroplysini-1 in the concentration range at 0.25–0.5 μM resulted in a time- and dose-dependent total tumor cell death in vitro.4.4. At a 10-fold higher concentration the compound did not reveal any cytostatic activity in normal human fibroblasts.5.5. From these data we conclude that (+)-aweroplysinin-1 represents a compound which displays a srong anti-tumor effect on EGF-dependent tumor cell lines.
The organic matrix of spicules of the alcyonarian coral, Lobophytum crassum, was studied to investigate its molecular characteristics and functional properties. The shape of the spicules was identified using scanning electron microscopy. The soluble organic matrix comprised 0.03% of the spicule weight. The SDS–PAGE analysis of the preparation showed four protein bands with apparent molecular weights of 37, 48, 67 and 102 kDa. The 67- and 102-kDa proteins appeared to be calcium binding proteins, detected as radioactive bands by 45Ca autoradiography. The 67-kDa protein appears to be glycosylated. The N-terminal amino acid sequence of the 67 kDa was determined; 7 of 20 residues were acidic. A database search for homologous proteins did not give a clear indication of the function of the 67-kDa protein. The isolated organic matrix possesses carbonic anhydrase activity which functions in calcium carbonate crystal formation, indicating that organic matrix is not only structural protein but also a catalyst. An interpretation of these results is that the spicule of alcyonarian corals has a proteinaceous organic matrix related to the calcification process.
Humic acid (HA) is a mixture of natural organic macromolecules having a range of physicochemical properties and exhibiting different reactivities in environmental systems. The objective of this study was to characterize chemical and molecular heterogeneity of HA by fractionating a bulk HA (BHA) into a series of subsamples, each having relatively homogeneous properties. The BHA was base extracted from Pahokee peat and was fractionated into eight fractions using an ultrafiltration apparatus with membranes having seven molecular cut-offs. The eight HA fractions obtained have apparent molecular sizes of <1, 1–3, 3–5, 5–10, 10–30, 30–100, 100–300 and >300 kDa, respectively, and their molecular size distributions were further calibrated using high performance size exclusion chromatography (HPSEC). The chemical and structural properties of the eight HA fractions were characterized systematically using elemental analysis, pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS), Fourier transform infrared (FTIR), ultraviolet–visible (UV–vis), and solid state 13C-nuclear magnetic resonance (13C-NMR) spectroscopy. The results show that each HA fraction has a relatively narrow distribution of molecular sizes on HPLC chromatographs, suggesting that ultrafiltration technique is effective for fractionating broadly heterogeneous humic macromolecules into relatively homogeneous fractions. UV–vis spectroscopy and Py-GC-MS analyses indicate that the fractions with lower molecular weights have more heterogeneous functional groups, greater O/C atomic ratios, and higher contents of oxygen and lignin-derived aromatic structural units. Conversely, the HA fractions with higher molecular weights have lower contents of oxygen and aromatic structural units that correspond to greater H/C and lower O/C atomic ratios. This study suggests that HAs formed under the same biogeochemical conditions may consist of macromolecules with a range of chemical, structural and molecular properties.
Surface sediments of Buzzards Bay, Massachusetts (BBP) are oxic to suboxic and are extensively bioturbated by deposit-feeding infauna, while sediments of the Pettaquamscutt River Estuary, Rhode Island (PRE) are reducing and overlain by anoxic bottom water. Sediments from these two sites were analyzed for total organic carbon and nitrogen, total hydrolyzable amino acids, dissolved free amino acids, and porewater dissolved organic carbon, ammonium, total carbon dioxide, and sulfide, to describe and compare the early diagenesis. Based on model calculations, organic matter remineralization rates in the upper meter of BBP and PRE sediments are of similar magnitude, at 14 and 10 g C/m2· year, respectively. The surface sediment organic carbon accumulation rates at the two sites are also similar, 36 (BBP) and 30 (PRE) g C/m2 · year. Thus, the unusually high organic content of PRE sediments (>12% by weight organic carbon) does not result from much greater deposition rates or from much lower decomposition rates than in BBP sediments, which contain only 2% organic carbon.Total hydrolyzable amino acids made up 11 to 23% of the total carbon remineralized in BBP sediments. Decomposition did not result in detectable changes in hydrolyzable amino acid composition at either site. Glutamic acid and β-aminoglutaric acid were major constituents of the sediment dissolved free amino acids. Dissolved free amino acid distributions in these sediments are probably the net result of production and consumption by bacteria. Macrofauna and adsorption to sediments are additional sinks for dissolved amino acids in Buzzards Bay sediments, but they do not appear to be responsible for the major features of the dissolved free amino acid distributions.
Marine natural products have become a major source of new chemical entities in the discovery of potential anticancer agents that potently suppress various molecular targets. In particular, the marine macrolides, which include an array of novel biomolecules endowed with outstanding cytotoxic and/or antiproliferative activities, are a prominent class of marine natural products that offer continued promise for breakthroughs in anticancer research. Herein we highlight some recent studies of promising marine macrolides, paying particular attention to their discovery, anticancer activities, mechanisms of action, chemical synthesis, and representative analogues.
Natural compounds obtained from marine organisms have received considerable attention as potential sources of novel drugs for treatment of human inflammatory diseases. Capnellene, isolated from the marine soft coral Capnella imbricate, 4,4,6a-trimethyl-3-methylene-decahydro-cyclopenta[]pentalene-2,3a-diol (GB9) exhibited anti-inflammatory actions on activated macrophages in vitro. Here we have assessed the anti-neuroinflammatory properties of GB9 and its acetylated derivative, acetic acid 3a-hydroxy-4,4,6a-trimethyl-3-methylene-decahydro-cyclopenta[]pentalen-2-yl ester (GB10).
Effects of GB9 or GB10 on the expression of inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2) in interferon-gamma (IFN-gamma)-stimulated mouse microglial BV2 cells were measured by Western blot. The in vivo effects of these compounds were examined in the chronic constriction injury (CCI) rat model of neuropathic pain, measuring thermal hyperalgesia, and microglial activation and COX-2 protein in lumbar spinal cord, by immunohistochemistry.
In BV2 cells, GB9 and GB10 inhibited the expression of iNOS and COX-2, stimulated by IFN-gamma. Intrathecal administration of GB9 and GB10 inhibited CCI-induced nociceptive sensitization and thermal hyperalgesia in a dose-dependent manner. Intraperitoneal injection of GB9 inhibited CCI-induced thermal hyperalgesia and also inhibited CCI-induced activation of microglial cells and up-regulation of COX-2 in the dorsal horn of the lumbar spinal cord ipsilateral to the injury.
Taken together, these data indicate that the marine-derived capnellenes, GB9 and GB10, had anti-neuroinflammatory and anti-nociceptive properties in IFN-gamma-stimulated microglial cells and in neuropathic rats respectively. Therefore, capnellene may serve as a useful lead compound in the search for new therapeutic agents for treatment of neuroinflammatory diseases.
Drugs from the sea are as much a potential marine resource as cultivated fish, and mineral deposits. The study of the chemical structure and properties of unusual metabolic products of marine life is a subject where marine ecology and the experimental sciences of chemistry, biochemistry, pharmacology and medicine share a common and complementary interest. The development of ad hoc collaboration between specialists has advanced basic knowledge and resulted in a significant feedback to marine biology and ecology as well as in the development of some useful drugs.
A significant proportion of the soluble protein of the organic matrix of mollusk shells is composed of a repeating sequence of aspartic acid separated by either glycine or serine. This regularly spaced, negatively charged aspartic acid may function as a template upon which mineralization occurs.
This review of phospholipase A2 (PLA2) inhibitors from marine organisms presents a compilation of research in this field over the past decade. As an introduction to the research on marine natural products, there is an overview of the role of PLA2 in inflammation that provides a rationale for seeking inhibitors of PLA2 as anti-inflammatory agents. A radiometric assay to measure inhibition of bee venom PLA2 is described in detail. Examples of marine natural products that inhibit PLA2 are manoalide and its derivatives, scalaradial and related compounds, the pseudopterosins, the vidalols, and a group of terpenoids that contain masked 1,4-dicarbonyl moieties.