Chloroplastic Glycolipids Fuel Aldehyde Biosynthesis in the Marine Diatom <i>Thalassiosira rotula</i>

Cutignano, Adele; d’Ippolito, Giuliana; Romano, Giovanna; Lamari, Nadia; Cimino, Guido; Febbraio, Ferdinando; Nucci, Roberto; Fontana, Angelo

doi:10.1002/cbic.200500343

Cited by 61 publications

(52 citation statements)

References 29 publications

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“…The mechanism of action of these compounds has yet to be elucidated. Chloroplast-derived glycolipids and membrane-bound phospholipids have been shown to be the main substrates for the biosynthetic pathway that produces antiproliferative polyunsaturated aldehydes 23,31 in wounded and nutrient-starved cells of marine diatoms. [32][33][34] It is also known that fatty acid hydroperoxides display teratogenic and proapoptotic properties.…”

Section: Resultsmentioning

confidence: 99%

Apoptosis-Inducing Galactolipids from a Cultured Marine Diatom, Phaeodactylum tricornutum

et al. 2008

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Two monogalactosyl diacylglycerols, 1 and 2, were isolated from the marine diatom Phaeodactylum tricornutum, using the patented ApopScreen cell-based screen for apoptosis-inducing, potential anticancer compounds. The molecular structures of the galactolipids were determined using a combination of NMR, mass spectrometry, and chemical degradation. The bioactivities were confirmed using a specific apoptosis induction assay based on genetically engineered mammalian cell lines with differential, defined capacities for apoptosis. The galactolipids induce apoptosis in micromolar concentrations. This is the first report of apoptosis induction by galactolipids.The oceans are the largest ecosystem of Earth and hold great, unexplored potential for drug discovery. One of the most important photosynthetic eukaryotes in marine ecosystems are the diatoms, 1 single-celled algae surrounded by a silica-derived wall. There are estimated to bẽ 10 6 species of diatoms, 2,3 which makes them ~4-fold more diverse than angiosperms. These organisms rose to ecological prominence over the past 40 million years, and in part, their success has been attributed not only to efficient resource acquisition strategies but also to allelochemical production that may favor their selection over competitors. Hence, we examined whether this group of organisms produces novel compounds capable of inducing apoptosis.The screening of organic extracts from marine algae and cyanobacteria for mechanism-based anticancer agents has become increasingly efficient and has led to the discovery of new chemotypes showing antiproliferative properties. 4,5 Cytotoxic chemo-therapeutics currently in use for the treatment of cancer rely on the ability to selectively target proliferating cells, which are enriched in tumors. Tumor cells progressively evolve genetic mutations that enable not only cell proliferation but also resistance to apoptosis, a cell suicide pathway that is the cellular response to oncogene activation or irreparable cellular damage. 6-9 Effective cancer therapeutic strategies often rely on preferential and efficient induction of apoptosis in tumor cells. Progressive exposure to such molecules commonly leads to selection of resistant cells that are therapeutically associated with both tumor progression and resistance to chemotherapy. [6][7][8][9] While many conventional cytotoxic chemotherapeutics trigger apoptosis indirectly by inflicting cellular damage, recent efforts have been directed to developing agents that specifically target or activate a caspase cascade that leads to apoptosis. 10In our ongoing effort to discover and develop new marine natural product biomedicinals, we have screened extracts from several marine organisms and have found that those isolated from a cultured marine diatom, Phaeodactylum tricornutum, possessed an ability to specifically induce apoptosis in immortal mammalian epithelial cells. Subsequently, extracts were subjected to ApopScreen bioas-say-guided purification, which resulted in the isolation of two monogalactos...

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Section: Resultsmentioning

confidence: 99%

Apoptosis-Inducing Galactolipids from a Cultured Marine Diatom, Phaeodactylum tricornutum

et al. 2008

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“…These teratogenic compounds, belonging to the complex class of oxylipins, including polyunsaturated aldehydes, are produced by the diatom cells from precursor membrane-bound lipids (Pohnert 2000;d'Ippolito et al 2004;Cutignano et al 2006). By definition, teratogens are substances that induce structural malformations in the offspring of organisms exposed to them during gestation.…”

Section: Phytoplankton-zooplankton Chemical Interactionsmentioning

confidence: 99%

New trends in marine chemical ecology

Ianora

Boersma

Casotti

et al. 2006

Estuaries and Coasts: J ERF

123

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This essay is the outcome of a colloquium convened in November 2005 at the Benthos Laboratory of the Stazione Zoologica Anton Dohrn in Ischia, Italy, on chemical ecology and the role of secondary metabolites in the structuring and functioning of marine biodiversity. The participants of the workshop are part of the European Network of Excellence MarBEF (Marine Biodiversity and Ecosystem Function), a consortium of 56 European marine institutes to integrate and disseminate knowledge and expertise on marine biodiversity. Here we review some of the new trends and emerging topics in marine chemical ecology. The first section deals with microbial chemical interactions. Microbes communicate with each other using diffusible molecules such as N-acylhomoserine lactones (AHL). These are regulators in cell-density-dependent gene regulation (quorum sensing) controlling microbial processes. In chemical interactions with higher organisms, microbes can act either as harmful pathogens that are repelled by the host's chemical defense or as beneficial symbionts. These symbionts are sometimes the true producers of the host's secondary metabolites that have defensive and protective functions for their hosts. We also describe how allelochemicals can shape phytoplankton communities by regulating competition for available resources, and also interactions among individuals of the same species. Compounds such as the diatom-derived unsaturated aldehydes have been demonstrated to act as infochemicals, and they possibly function as a diffusible bloom-termination signal that triggers an active cell death and bloom termination at sea. The same molecules have also been shown to interfere with the reproductive capacity of grazing animals deterring future generations of potential predators. Such compounds differ from those that act as feeding deterrents since they do not target the predator but its offspring. Many of the neurotoxins produced by dinoflagellates act as feeding deterrents, and laboratory experiments have shown that ingestion of these algae by some microzooplankton and macrozooplankton can cause acute responses such as death, incapacitation, altered swimming behavior, and reduced fecundity and egg-hatching success. These effects may rarely occur in nature because of low individual grazing rates on dinoflagellate cells and grazing on other food sources such as microflagellates and diatoms. We also consider the nutritional component of marine plant-herbivore interactions, especially in the plankton, and the information available on the effects of growing conditions of algae on the production of toxic metabolites. Species producing saxitoxins seem to consistently produce the highest amounts of toxins (on a per cell basis) in the exponential phase of growth, and there is a decrease in their production under nitrogen, but not under phosphorus stress, where the production actually increases. We try to explain the circumstances under which organisms defend themselves chemically and argue that the most likely explanatory model for ...

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“…Injury to the tissue during preparation of the samples, for example during lipid extraction, freezing and thawing might activate the lipolytic acyl-hydrolase, specifically phospholipase and galactoli- pase, which could hydrolyze the phospholipids and glycoglycerolipids, respectively, to produce FFA. These phenomena were also observed in the marine diatom Thalassiosira rotula 11,18) , the red alga G. chilensis 10) , and in higher plants 19) where the wounding of the cells activated phospholipase and galactolipase to produce FFA as a substrate for oxylipin biosynthesis.…”

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confidence: 71%

“…For this purpose, the activity of lipid acyl-hydrolase, which is responsible for the change in lipid composition of algae, was measured. Degradation of lipids by acyl-hydrolase was recently examined in the brown alga Cladosiphon okamuranus 8) , the red algae Gracilaria vermiculophylla 9) and G. chilensis 10) , the marine diatom Thalassiosira rotula 11) and the red tide flagellate Chattonella marina 12) , and was found to be responsible for reduced amounts of polar lipids and the production of free fatty acids (FFA).…”

Section: Introductionmentioning

confidence: 99%

“…In most of the red algae, MGDG and PC are rich in polyunsaturated fatty acids, especially 20:4n-6 and 20:5n-3 20,21,27,34) . The 20:4n-6 acid plays an important role in biological processes for the formation of chemical defense in the marine diatom Thalassiosira rotula 11,18) and in the red alga G. chilensis 10) and as a substrate for the formation of prostaglandins and aldehydes in the red alga G. verrucosa 35) and in the brown alga Laminaria angustata 36) . The FFA composition of E. wentii shows that 16:0 (32.8%) and 20:4n-6 (30.0%) are the predominant fatty acids ( ).…”

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confidence: 99%

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Lipid Class and Fatty Acid Composition of a Little-known and Rarely Collected Alga Exophyllum wentii Weber-van Bosse from Bali Island, Indonesia

et al. 2009

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The lipid class and fatty acid composition of a little-known and rarely collected alga Exophyllum wentii from Bali Island, Indonesia were determined for fresh and frozen-thawed samples using thin-layer chromatography, gas-liquid chromatography, and high-performance liquid chromatography. Glycoglycerolipids, which mainly consisted of mongalactosyldiacylglycerols (MGDG) and digalactosyldiacylglycerols (DGDG), were the predominant lipid components, accounting for 67% and 56% of the total polar lipid content in the fresh and frozen-thawed samples, respectively. Phospholipids, including phosphatidylcholines (PC) and phosphatidylglycerols (PG), were detected with lesser amounts in both samples (16 -17% of the total polar lipid content). Free fatty acids (FFA), sterols and triacylglycerols (TAG) were also detected in minor quantities; however, the FFA content in the frozen-thawed sample increased to up to 20% of the total lipid content, suggesting that hydrolysis of the membrane lipids had occurred. A crude enzyme preparation from the alga showed activities for hydrolyzing the acyl groups of the phospholipids and glycoglycerolipids. Palmitic acid (16:0) and arachidonic acid (20:4n-6) were the major fatty acids in both the total lipid and in individual polar lipid classes as well as the dominant fatty acids released from the membrane lipids by enzymatic hydrolysis. The high level of 20:4n-6 (29%) in the total lipid and the presence of considerable amounts of PC (11% of the total polar lipid) and PG (6.2%) support classification of E. wentii into the Division Rhodophyta.

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Chloroplastic Glycolipids Fuel Aldehyde Biosynthesis in the Marine Diatom Thalassiosira rotula

Cited by 61 publications

References 29 publications

Apoptosis-Inducing Galactolipids from a Cultured Marine Diatom, Phaeodactylum tricornutum

Apoptosis-Inducing Galactolipids from a Cultured Marine Diatom, Phaeodactylum tricornutum

New trends in marine chemical ecology

Lipid Class and Fatty Acid Composition of a Little-known and Rarely Collected Alga Exophyllum wentii Weber-van Bosse from Bali Island, Indonesia

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