Marine Natural Products Chemistry Research Articles

Bromopyrrole Carboxamide Biosynthetic Products from the Caribbean Sponge Agelas dispar

Two new bromopyrrole alkaloids, dispyrin (6) and dibromoagelaspongin methyl ether (12), were isolated from the Caribbean sponge Agelas dispar, collected near the Venezuelan island La Blanquilla, and their structures were elucidated from spectroscopic data analysis. Dispyrin (6) contains a novel bromopyrrole tyramine motif that has no precedent in marine natural products chemistry and represents a notable variation from the oroidin class compounds consistently produced by species of Agelas in general. Compounds isolated from Caribbean Agelas species were found to possess a unique biogeographical bromination trend.

State‐of‐Art Methodology of Marine Natural Products Chemistry: Structure Determination with Extremely Small Sample Amounts

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Drugs from the deep

Is the cure for cancer lurking beneath the waves? Emma Marris plunges into the chemistry of marine natural products.

Chemistry and Biology of Anti-Inflammatory Marine Natural Products:Molecules Interfering with Cyclooxygenase, NF-kB and Other Unidentified Targets

The majority of the anti-inflammatory drugs routinely used nowadays are COX (cyclo-oxygenase) inhibitors. The important role of this enzyme, once known as prostaglandin synthase, in inflammation came a consequence of the discovery by the Nobel prize winner John Vane with his path-breaking discovery that aspirin and similar drugs exert their action by blocking the biosynthesis of the prostaglandin group of lipid mediators. (John R. Vane, Nobel Lecture, December 8, 1982 and references cited therein) In the last five years it has become clear that there are two such enzymes involved. One of the "cyclo-oxygenases", called COX1 is responsible for making prostaglandins, which among other things, protect the stomach and kidney from damage. It is now clear that inhibition of COX1 accounts for the unwanted side effects of aspirin-like drugs such as gastric irritation and renal damage. The other enzyme, COX2, is induced by inflammatory stimuli and it is prostaglandins made by this enzyme that contribute to the inflammation in diseases such as rheumatoid arthritis. However, concerning inflammation-related targets, one should not limit the interest to COX and PLA2 enzymes. In recent years, it has steadily become more clear, that modulation in the expression of genes underlies most cellular responses, and inflammation is certainly not an exception in this sense. It does not come as surprise that molecules showing ability to interfere with factors involved in the modulation of genes expression, such as NF-kB, have also to be considered potential anti-inflammatory agents. Also in this respect, marine natural products (MNP) have brought a collection of novel molecular entities displaying ability to target COX1/COX2, NF-kappaB or acting through molecular mechanisms yet-to-be-discovered. Following, the marine natural products accounted for within this review will be grouped on the basis of their bio-molecular targets. Chemical synthesis of particular relevant molecules will be also discussed, especially in those cases where the natural products can be considered as lead compounds for the development of simplified derivatives or analogues of potential pharmaceutical interest.

Secondary Metabolites from the South China Sea Invertebrates: Chemistry and Biological Activity

The increasing demand for new lead compounds in the pharmaceutical and agrochemical industries has driven scientists to search for new sources of bioactive natural products. Marine invertebrates are a rich source of novel, bioactive secondary metabolites and they have attracted a great deal of attention from scientists in the fields of chemistry, pharmacology, ecology, and molecular biology. During the past 25 years, many complex and structurally unique secondary metabolites have been isolated from the invertebrates inhabiting the South China Sea. These metabolites are responsible for various bioactivities such as anti-tumor, anti-inflammation and antioxidant activities, and/or they act on the cardiovascular system. This review will focus on the marine natural product chemistry of invertebrates from the South China Sea, aiming to give the reader a brief view of the compounds isolated from these invertebrates, as well as their biological activities. The article covers the literature published during the period from the beginning of 1980 to the end of 2005, with 340 citations and 811 compounds from invertebrates from the South China Sea, including sponges, coelenterates, molluscs and echinoderms.

Drug discovery and sea hares: bigger is better

Traditionally, small molecules (<1kDa) have dominated the study of the chemistry and chemical ecology of marine natural products. However, as reported in a recent publication, Yang and co-workers have isolated a 60-kDa antibacterial protein from the defensive secretions of the sea hare Aplysia californica. This protein, escapin, has been characterized as an l-amino acid oxidase with bacteriostatic and bacteriocidal activities. Their work highlights the largely untapped biomedical potential of marine organism-derived proteins and addresses the problems of supply associated with invertebrate natural products. It also leads to intriguing hypotheses about the ecological function(s) of the new protein.

2004 RACI One-day Natural Products Group Symposium

is dedicated to the Royal Australian Chemical Institute’s Natural Products group. The group meets annually, in the first week of October, for a one-day symposium at a venue in the state of New South Wales (NSW), Australia. This year’s program was held at Southern Cross University (SCU) in Lismore and attracted a large audience from Queensland, as well as NSW, because of Lismore’s proximity to the Queensland border. The most recent program can be found on the web at http://www.chem.mq.edu.au/npg. This collection of seven papers form the proceedings of the 2004 one-day symposia and I would like to thank the authors for their patience and our sponsors Davies Collison Cave, Biosignal, Agilent Technologies, Medos and of course the Royal Australian Chemical Institute (RACI) for their generous support. Natural products chemistry has a long history in Australia. In fact, the first chemistry department in the country, at the University of Sydney, was founded on natural products chemistry with such great names as H. G. Smith, Sir Robert Robinson, Ernest Ritchie, W. C. Taylor and Rod Richard, to name just a few. Australia’s unique flora and fauna has assured more or less continuous interest in natural products chemistry in this country, both terrestrially and (more recently) in the marine environment. However, interest in natural products and natural product chemistry has surged in the last year or two and we all hope that this trend continues, spurred on by the new Biotech boom that is focused on the pharmaceutical industry and the quest for new products for human health. The scientific program reflected the current state of natural products chemistry in Australia and the first paper in the special issue, by Ian Southwell, set the scene by outlining the history of natural products research in the Department of Primary Industries over the past 25 years. An historic perspective also opened the Symposium, with a lecture from Peter Waterman, who also opened the 1999 RACI Natural Products Symposium [1]. At that time, Southern Cross University lured Peter from the UK with the promise of a Centre for Phytochemistry (now Centre of Phytochemistry and

Chemistry and Biology of Anti-Inflammatory Marine Natural Products. Phospholipase A2 Inhibitors

The chemical and biological properties of anti-inflammatory marine natural products whose mechanism of action involves inhibition of phospholipase A2 (PLA2), an enzyme of key importance in the biosynthesis of proinflammatory chemical signals and mediators, has been reviewed. Remarkably, most marine natural products display a selective inhibition profile against secretory PLA2 enzymes, with little or null ability to interfere with cytosolic PLA2. Variabilin, a marine furano-terpene, appears to be a notable exception, endowed with a distinctive dual inhibitor profile towards both secretory and cytosolic PLA2 proteins. Keywords: inflammation, sesterterpenoids, manoalide, pla2 enzymes, cacospongionolides, luffariellolides, petrosaspongiolides

Research achievement award--D. John Faulkner.

David John Faulkner, one of the pioneers of marine natural products chemistry and the 2003 recipient of the ASP Research Achievement Award, passed away on November 23, 2002. John was very pleased to learn that he'd been named as the award recipient and was intending to present the ASP Research Achievement Award Address at the annual meeting in July 2003, Chapel Hill, North Carolina. John's untimely death left an unprecedented event in the history of the ASP-a posthumous Research Achievement Award to a deserving individual and an untimely loss for us all. We are bereft of a colleague, a friend, and a mentor, and the opportunity to hear John's words on the occasion of his own award. In tribute to John, we have assembled a retrospective of John's work that is not meant to be a comprehensive review (this would take considerably more space) but a selection of highlights and personal vignettes from some of those that trained in marine natural products under his mentorship. This paper is a written account of the symposium presented by the authors at the ASP Annual Meeting in Chapel Hill, North Carolina, on July 16, 2003.

Challenges and rewards of research in marine natural products chemistry in Brazil.

Brazil is blessed with a great biodiversity, which constitutes one of the most important sources of biologically active compounds, even if it has been largely underexplored. As is the case of the Amazon and Atlantic rainforests, the Brazilian marine fauna remains practically unexplored in the search for new biologically active natural products. Considering that marine organisms have been shown to be one of the most promising sources of new bioactive compounds for the treatment of different human diseases, the 8000 km of the Brazilian coastline represents a great potential for finding new pharmacologically active secondary metabolites. This review presents the status of marine natural products chemistry in Brazil, including results reported by different research groups with emphasis on the isolation, structure elucidation, and evaluation of biological activities of natural products isolated from sponges, ascidians, octocorals, and Opistobranch mollusks. A brief overview of the first Brazilian program on the isolation of marine bacteria and fungi, directed toward the production of biologically active compounds, is also discussed. The current multidisciplinary collaborative program under development at the Universidade de São Paulo proposes to establish a new paradigm toward the management of the Brazilian marine biodiversity, integrating research on the species diversity, ecology, taxonomy, and biogeography of marine invertebrates and microorganisms. This program also includes a broad screening program of Brazilian marine bioresources, to search for active compounds that may be of interest for the development of new drug leads.

Chemistry and biology of new marine alkaloids from the indole and annelated indole series.

Chemistry and biology of marine natural products from the indole and annelated indole series have become an attractive research field for development of new pharmacological lead substances. In the past years some of the isolated natural organic compounds were synthesized by chemists and evaluated with great enthusiasm to find new lead natural compounds against different diseases. In this review the latest results for new compounds including isolation, biological evaluation, synthetic pathways and some retrosynthetic analyses are summarized.

Secondary metabolites from marine microorganisms.

After 40 years of intensive research, chemistry of marine natural products has become a mature field. Since 1995, there are signals of decreased interest in the search of new metabolites from traditional sources such as macroalgae and octocorals, and the number of annual reports on marine sponges stabilized. On the contrary, metabolites from microorganisms is a rapidly growing field, due, at least in part, to the suspicion that a number of metabolites obtained from algae and invertebrates may be produced by associated microorganisms. Studies are concerned with bacteria and fungi, isolated from seawater, sediments, algae, fish and mainly from marine invertebrates such as sponges, mollusks, tunicates, coelenterates and crustaceans. Although it is still to early to define tendencies, it may be stated that the metabolites from microorganisms are in most cases quite different from those produced by the invertebrate hosts. Nitrogenated metabolites predominate over acetate derivatives, and terpenes are uncommon. Among the latter, sesquiterpenes, diterpenes and carotenes have been isolated; among nitrogenated metabolites, amides, cyclic peptides and indole alkaloids predominate.

Determination of elements in algae by different atomic spectroscopic methods

The chemistry of substances derived from plants has received a great deal of attention in the last several decades. Today, natural products and their synthetic analogs also play an important role in the pharmaceutical and food industry. Several interesting reviews on algae were published in the last 10 years. Algae, especially the red algae, are very helpful in every day practice in many fields, e.g. algal polysaccharides, agar, carrageenan and some algae extracts are used in agricultural, medicines and in food products, respectively ( The Constituents of Red Algae, 1999; Gelling Hydrocolloids in Food Products Applications, 1979, p. 186; Marine Natural Products Chemistry, 1997, p. 337; Algae Polysaccharides, 1983, p. 195). The biological and pharmaceutical properties promote interest among chemists to focus their attention on algae, as yet, a wide open field (Synthesis and Proceedings of the Second EUMAC Workshop, Marine Eutrophication and Bentic Macrophytes, p. 2). The most extensively studied algal phyla are Chlorophyceae (green algae) (J. Phycol. 26 (1990) 670), Rhodophyceae (red algae) (J. Phycol. 25 (1989) 522) and Phaeophyceae (brown algae) (J. Phycol. 31 (1995) 325; J. Phycol. 32 (1996) 614). Concentrations of four elements (Ca, Mg, K, Na) were determined in the above-mentioned algal phyla by different atomic spectroscopic methods (F-AES, ICP-AES) after the digestion of algal samples with cc. HNO 3 in a microwave apparatus. Not only the Ca and Mg contents, but the ratio of the calcium to magnesium was calculated in every case. This ratio was lower (0.5–0.8) in green algae than in the red and brown algae (1.3–14.4). Therefore, the green algae are better magnesium sources than the red and brown. The elemental composition is of great importance in the ion system of human organism. It is usually characterized by the ion quotient ([Ca 2+]+[Na +]:[Mg 2+]+[K +]), which is approximately 1.0 under ideal conditions. However, in the human body this mole ratio generally varies between 2.5 and 4.0. The ion quotient was calculated by averaging between 1 and 2 in different algal phyla. This means that the 2.5–4.0 mole ratio can be decreased by different algal foods in the human organism.

Highlights of marine natural products chemistry (1972-1999).

Marine Natural Products Chemistry is essentially a child of the 1970's that developed rapidly during the 1980's and matured in the last decade. With a few notable exceptions, it is difficult to select individual papers that significantly impacted the field. However, marine natural products chemistry has often influenced other fields and that aspect is the focus of this review. It is clear that the early directions taken by marine natural products chemists drew as much from the examples provided by insect chemical ecology as from the longer history of phytochemistry. By 1975 there were already three parallel tracks in marine natural products chemistry: marine toxins, marine biomedicinals and marine chemical ecology. It is the integration of the three fields of study that has given marine natural products chemistry its unique character and vigour.

THE CHEMICAL SYSTEMATICS OF COLONIAL MARINE ANIMALS: AN ESTIMATED PHYLOGENY OF THE ORDER GORGONACEA BASED ON TERPENOID CHARACTERS

The classification of colonial marine invertebrates is often very difficult. The purpose of this paper is to illustrate the potential of numerical chemotaxonomy and cladistic analysis to facilitate the study of the evolution of these organisms. Chemotaxonomy has contributed little to the study of these animals, in spite of the large amounts of data generated by marine natural products chemistry. Existing chemosystematic investigations of colonial animals have not employed the methods of numerical taxonomy or of cladistic analysis. As an example of the usefulness of such an approach, cladistic analysis on quantified chemical data was performed for nineteen species of gorgonians. This produced cladograms which, for the most part, agreed with classical gorgonian systematics, but which also yielded several new insights into the evolution and classification of gorgonians. Numerical chemotaxonomy and cladistic analysis should not continue to be ignored as a tool for the study of phylogenetic relationships among groups of colonial marine invertebrates.

Marine natural products revisited

Some of the most recent intriguing reports on the chemistry of marine natural products include work with saxitoxin, the paralytic shellfish poison with other toxin, and with chemical signal and defense agents.

Marine Natural Products Chemistry. D. J. Faulkner , W. H. Fenical

<i>Marine Natural Products Chemistry</i>. D. J. Faulkner , W. H. Fenical

Marine Natural Products Chemistry: Proceedings of a Conference on Marine Natural Products held in Jersey, Channel Islands, United Kingdom, October 12-17, 1976 sponsored by the NATO Special Program Panel on Marine Sciences. Edited By D.J. Faulkner and W.H. Fenical. New York and London: Plenum Press, 1977. x,433 pp. (NATO Conference Series: IV Marine Sciences, 1) Price $42.50

Marine Natural Products Chemistry: Proceedings of a Conference on Marine Natural Products held in Jersey, Channel Islands, United Kingdom, October 12-17, 1976 sponsored by the NATO Special Program Panel on Marine Sciences. Edited By D.J. Faulkner and W.H. Fenical. New York and London: Plenum Press, 1977. x,433 pp. (NATO Conference Series: IV Marine Sciences, 1) Price $42.50

Interesting aspects of marine natural products chemistry

Interesting aspects of marine natural products chemistry

Natural products from porifera.

Since organic chemistry began, the chemistry of natural products from terrestrial organisms such as plants and fungi has been studied intensively; in contrast, marine species have received relatively little attention. However, in the last decade research in the field of marine products has increased sbstantially. The heightened interest in this area is attested by the appearance of the monumental treatise of Halstead on Poisonous and Venomous Marine Animals in 1965 (108), Baslow’s review on “Marine Pharmacology” in 1969 (14) and Scheuer’s recent book “Chemistry of Marine Natural Products” (160) in 1973. In addition Premuzic’s review devoted to the Chemistry of Natural Products Derived from Marine Sources, was published in volume 29 of this series in 1971 (152).KeywordsNatural ProductMarine SpongeFuran RingTetrahedron LetterTotal Sterol ContentThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.