1,721,022 research outputs found
Stories from the Caribbean sponge Plakortis simplex: from structure elucidation to studies of biosynthetic pathways
No full textChemical analysis of Plakortis simplex sponge extract provided a number of structurally unique secondary metabolites, including the antimalarial polyketide plakortin, the IL-10 inducing simplexide and other unusual glycolipids, and hopanoids. The hypothesis that they could be products of symbionts was explored by a multi-step strategy: i) cell separation of the fresh sponge tissue in combination with chromatographic and spectroscopic analysis; ii) PCR experiments to prove the presence of key enzymes of the biosynthesis of glycolipids and polyketides; iii) cultivation and screening of GSL-producing bacteria; iv) screening of metagenomic DNA of P. simplex in search of a PKS compatible with the structure of plakortin
A new inositol-hopanoid from an Indonesia specimen of the sponge Plakortis simplex
No full textThe Caribbean sponge Plakortis simplex has been extensively studied by our group, and a large variety of unusual glycolipids and other amphiphilic compounds have been isolated, including simplexide, discoside, and 12-methylbacteriohopanetetrol .Recently, we had occasion to analyze for glycolipids an Indonesian specimen of P. simplex. In spite of the geographical distance, we found that the glycolipids composition of the Indonesian and Caribbean specimens were very similar. However, the Indonesian P. simplex also contained a new glycolipid, combining structural features of hopanoids and discoside, whose structure elucidation will be described
A New Furanose-Rich Pentaglycosylated GSL from the Sponge Terpios sp.
No full textMarine organisms represent a prolific source of compounds with pharmacological properties. Among these our attention is paid to glycolipids from sponges. Many studies on glycolipids demonstrated their activity on the immune system1 and their influence on angiogenesis and tumor cells proliferation, and therefore they are potentially useful in the therapy against several diseases.Recent investigation of the glycosphingolipid (GSL) composition of the marine sponge Terpios sp. revealed the presence of terpioside A, the first diglycosylceramide having a L-fucofuranose unit in the sugar chain of the molecule. A further investigation of GSL composition of Terpios sp. showed the presence of Terpioside B, a new furanose-rich pentaglycosylated glycosphingolipid, characterized by the presence of two terminal α-L-fucofuranose units.
The structure of terpioside B was elucidated using extensive 2D NMR and mass spectrometry studies. In addition, microscale chemical degradation was performed in order to establish the absolute configuration of the whole molecule as well as the length and the nature of the alkyl chains of the ceramide portion
Environmental impact assessment: A multilevel, multi-parametric framework for coastal waters
Full text linkIn any process of Environmental Impact Assessment (EIA) a key role is played by the action of monitoring. Indeed, the acquisition of real field data provides the evidence of the environmental status and identifies hazards and sources of pollution. When environmental pollution is revealed, it is important to identify the source following the source-path-target model. However, when monitoring operations are planned, often the three-dimensional (3D) nature of monitored hotspots is neglected. Instead, information can be gathered through a multi-parametric, multi-level framework, which combines multiple disciplines and generates correlations between several data sets acquired in the analysed scenario. This novel new framework is named MuM3, meaning that the proposed Monitoring (M) is MultiDisciplinary, Multi-level and Multi-parametric (i.e. Mu) and it is developed in all the three dimensions of physical space (the superscript ‘3’). This paper outlines the implementation of this framework. In particular, monitoring polluted coastal waters refers to one of the critical areas identified by EIA regulations. The framework incorporates different spatial scales of observation (Levels) and the potential sensors that can be used at each Level. A three-step work-flow model describes the raw data acquisition and the transformation and integration of different indicators into useful information for EIA. A schematic flow chart describes the approach to developing multi-level, multi-parameter connections. Extension of this framework can be applied to any EIA, especially in the case of critical areas that are identified by the regulations as: (i) Wetlands, riparian areas, river mouths; (ii) Mountain and forest areas; (iii) Nature reserves and parks; (iv) Densely populated areas; (v) Landscapes and sites of historical, cultural or archaeological significance
HIERARCHICAL MONITORING OF WATER QUALITY: COORDINATING THE SPATIOTEMPORAL RESOLUTION OF MULTILAYER AND MULTISPECTRAL SENSORS TO CHARACTERIZE POLLUTION
No full textGlycolipids from sponges. 19. Terpioside from the marine sponge Terpios sp., the first glycosphingolipid having an L-fucofuranose unit
No full textThe new diglycosylceramide terpioside has been isolated from the marine sponge Terpios sp. Terpioside is a diglycosylated glycosphingolipid which is the first example of a natural glycosphingolipid having an L-fucofuranose unit. The structure of terpioside was elucidated by extensive spectroscopic analysis, whereas chemical degradation was used to establish the nature of the alkyl chains and the absolute configuration of the sugars and of the ceramide stereogenic centers
Glycolipids from Sponges. Part 21. Amphiceramide A and B, Novel Glycosphingolipids from the Marine Sponge Amphimedon compressa
No full textGlycolipid analysis of the Caribbean sponge Amphimedon compressa showed it to contain two novel glycosphingolipids, amphiceramide A and B , possessing an unusual Δ6-phytosphingosine. The saccharide chain of amphiceramide A is composed of a β-glucose residue glycosylated at position 6 by an N-acetyl-β-glucosamine, and has never been found before in a natural product. The saccharide chain of amphiceramide B consists of an allolactose [Gal(1β→6)Glc] residue β-linked to the ceramide and is found here for the first time in a natural glycosphingolipid. In addition, the sponge contains a new molecular species of acetamidoglucosyl ceramide , and known glucosyl ceramide (halicerebroside A) and melibiosyl ceramide (amphimelibioside C)
When Synthesis Gets It Wrong: Unexpected Epimerization Using PyBOP in the Synthesis of the Cyclic Peptide Thermoactinoamide A
No full textGlycolipids from sponges. 22. Terpioside B, a difucosyl GSL from the marine sponge Terpios sp. is a potent inhibitor of NO release
No full textTerpioside B, a unique glycolipid containing two fucose residues in the furanose form in its pentasaccharide chain, was isolated from the marine sponge Terpios sp. Its complete stereostructure was solved by interpretation of mass spectrometric and NMR data along with CD and GG-MS analyses of its degradation products. Terpioside B is a potent inhibitor against LPS-induced NO release, and is considerably more active than simpler glycosphingolipids such as terpioside A and monoglucosylceramide
A Biotechnological Approach for Plakortin Production: New Perspectives for Bioactive Compounds from Marine Source
No full textA variety of limiting factors currently affect the full exploitation of bioactive natural products from marine invertebrates, the most important being the supply problem. Large-scale total synthesis is usually prevented by the complex structure of most natural products, while a massive collection of the organisms producing compounds of industrial interest appears unrealistic. New perspectives were opened by the discovery that several (and probably a significant portion) of these bioactive compounds are produced by bacterial symbionts, but even so, production by fermentation is often impossible because very few symbiotic species can be cultured with the present techniques.
We are currently exploring a biotechnological approach for the inexpensive and reproducible production of marine natural compounds. Our research is focused on the study of the biosynthetic pathway of plakortin (and related compounds), a polyketide peroxide with interesting antimalarial properties which is present in the marine sponge Plakortis simplex and is biosynthesized by a uncultivable bacterial symbiont of the sponge. We intend to identify, isolate and sequence the biosynthetic gene cluster for plakortin (presumably coding for a type-I polyketide synthase), and subsequently to express the pathway heterologously to produce plakortin by fermentation.
Metagenomic DNA from Plakortis simplex was cloned to generate a 50,000 clone library which was PCR-screened in search of the PKS gene cluster involved in the biosynthesis of plakortin. One positive clone was isolated and fully shotgun sequenced. The PKS gene is located at one end of the insert, so that only a small part of the PKS gene cluster is present in the insert (9 kbp). Following these encouraging results, we are currently searching for the remaining part of the cluster.
The latest results of this project will be presented. The success of this research will demonstrate the feasibility of this strategy for the large-scale production of natural products, which could be applied to many other bioactive compounds from marine invertebrate
- …
