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1.
J Nat Prod ; 82(6): 1627-1633, 2019 06 28.
Artigo em Inglês | MEDLINE | ID: mdl-31117523

RESUMO

Four kainic acid (KA, 1)-related compounds, 4-hydroxykainic acid (2), allo-4-hydroxykainic acid (3), N-dimethylallyl-l-glutamic acid (4), and N-dimethylallyl- threo-3-hydroxyglutamic acid (5), were isolated from the red alga Digenea simplex. The structures of these compounds were elucidated using spectroscopic methods. Compounds 2 and 3 are possible oxidative metabolites of KA and allo-KA (6), respectively. Compound 4 was recently reported as the biosynthetic precursor of KA, but the absolute configuration of 4 has not been previously determined. Herein, we determined the absolute configuration of 4 as 2( S) using advanced Marfey's method. Compound 5 is similar to N-geranyl-3( R)-hydroxy-l-glutamic acid (8), which was previously identified in a domoic acid (DA)-containing red alga. Compounds 5 and 8 are predicted to be biosynthetic byproducts of the radical-mediated cyclization reaction to form the pyrrolidine rings of KA and DA, respectively. Furthermore, the toxicities of 1-5 in mice were examined by intracerebroventricular injection. The toxicity of 2 was less than that of KA; however, the mice injected with 2 showed symptoms similar to those induced by KA, while 3-5 did not induce typical symptoms of KA in mice.

2.
Sci Rep ; 8(1): 356, 2018 01 10.
Artigo em Inglês | MEDLINE | ID: mdl-29321590

RESUMO

Domoic acid (DA, 1), a potent neurotoxin that causes amnesic shellfish poisoning, has been found in diatoms and red algae. While biosynthetic pathway towards DA from geranyl diphosphate and L-glutamate has been previously proposed, its late stage is still unclear. Here, six novel DA related compounds, 7'-methyl-isodomoic acid A (2) and B (3), N-geranyl-L-glutamic acid (4), 7'-hydroxymethyl-isodomoic acid A (5) and B (6), and N-geranyl-3(R)-hydroxy-L-glutamic acid (7), were isolated from the red alga, Chondria armata, and their structures were determined. The compounds 4 and 7, linear compounds, are predictable as the precursors to form the DA pyrrolidine ring. The compounds 2 and 3 are thought as the cyclized products of 7; therefore, dehydration and electron transfer from the internal olefin of 7 is a possible mechanism for the pyrrolidine ring formation. One terminal methyl group of the side chain of 2 and 3 is predicted to be oxidized to hydroxymethyl (5, 6), and then to carboxylic acids, forming isodomoic acids A and B. Finally, the terminal olefin of isodomoic acid A would be isomerized to form DA. In addition, [15N, D]-labeled 4 was incorporated into DA using the diatom, Pseudo-nitzschia multiseries, demonstrating that 4 is the genuine precursor of DA.


Assuntos
Diatomáceas/metabolismo , Ácido Caínico/análogos & derivados , Rodófitas/química , Vias Biossintéticas , Cromatografia Líquida , Ácido Caínico/química , Ácido Caínico/metabolismo , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Estrutura Molecular
3.
Harmful Algae ; 60: 139-149, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-28073557

RESUMO

The distribution of the toxic pennate diatom Nitzschia was investigated at four mangrove areas along the coastal brackish waters of Peninsular Malaysia. Eighty-two strains of N. navis-varingica were isolated and established, and their identity confirmed morphologically and molecularly. Frustule morphological characteristics of the strains examined are identical to previously identified N. navis-varingica, but with a sightly higher density of the number of areolae per 1µm (4-7 areolae). Both LSU and ITS rDNAs phylogenetic trees clustered all strains in the N. navis-varingica clade, with high sequence homogeneity in the LSU rDNA (0-0.3%), while the intraspecific divergences in the ITS2 data set reached up to 7.4%. Domoic acid (DA) and its geometrical isomers, isodomoic A (IA) and isodomoic B (IB), were detected in cultures of N. navis-varingica by FMOC-LC-FLD, and subsequently confirmed by LC-MS/MS, with selected ion monitoring (SIM) and multiple reaction monitoring (MRM) runs. DA contents ranged between 0.37 and 11.06pgcell-1. This study demonstrated that the toxigenic euryhaline diatom N. navis-varingica is widely distributed in Malaysian mangrove swamps, suggesting the risk of amnesic shellfish poisoning and the possibility of DA contamination in the mangrove-related fisheries products.


Assuntos
Diatomáceas/metabolismo , Ácido Caínico/análogos & derivados , Animais , DNA Ribossômico/genética , Ácido Caínico/metabolismo , Malásia , Filogenia , Especificidade da Espécie
4.
PLoS One ; 10(6): e0128149, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26065892

RESUMO

We analyzed the Hg concentration, and δ¹³C and δ¹5N values in the scalp hair of residents from seven countries; Vietnam, New Zealand, Spain, the USA, South Korea, Brazil and Japan. Relationships among the data in each country and among the seven countries were then examined. The highest Hg concentration as well as the highest or higher δ¹5N value in each country was found in the hair of a heavy marine fish-eater, whereas the lowest Hg concentration and δ¹5N value were found in the hair of a vegetarian or non (marginal)-fish eater. Hg concentrations were positively correlated with the δ¹5N values in each country, and increased markedly in samples with δ¹5N values exceeding 9.0 ‰, probably due to fish consumption. The highest Hg concentration could be found in sample, with a δ¹³C value between -19 and -18‰, probably reflecting the δ¹³C value of the marine food web.


Assuntos
Isótopos de Carbono , Comportamento Alimentar , Cabelo/química , Mercúrio , Isótopos de Nitrogênio , Animais , Brasil , Peixes , Humanos , Japão , Nova Zelândia , Plantas Comestíveis , República da Coreia , Espanha , Estados Unidos , Vietnã
5.
J Phycol ; 48(5): 1232-47, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27011282

RESUMO

Field sampling was undertaken to investigate the occurrence of Pseudo-nitzschia Peragallo species in eight locations along the coast of Malaysian Borneo. A total of 108 strains of Pseudo-nitzschia species were isolated, and their morphology examined with SEM and TEM. Additionally, molecular data from nuclear-encoded partial LSU rDNA, and ITS regions, were characterized. A total of five species were confidently identified based on a combination of distinct morphological characteristics and supporting molecular evidence: P. brasiliana Lundholm, Hasle & Fryxell, P. cuspidata (Hasle) Hasle, P. dolorosa Lundholm & Moestrup, P. micropora Priisholm, Moestrup & Lundholm, and P. pungens (Grunow) Hasle var. pungens. However, one morphotype from Sarawak, while somewhat similar to P. caciantha, showed significant morphological distinction from this and any other of the currently described species. Most notably this morphotype possessed a characteristic pore arrangement in the poroids, with the fine pores in each perforation sector arranged in circles. Pair-wise sequence comparison of the LSU rDNA between this unidentified morphotype and P. caciantha Lundholm, Moestrup & Hasle, revealed 2.7% genetic divergence. Phylogenetic analyses strongly supported the monophyly of the morphotype. Based upon these supporting data it is here described as a new species, Pseudo-nitzschia circumpora sp. nov. A key to the six species of Pseudo-nitzschia from Malaysian Borneo is presented. Molecular signatures for all species were established based on structural comparisons of ITS2 rRNA transcripts.

6.
Food Chem Toxicol ; 49(9): 2167-71, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21672599

RESUMO

The intestinal absorption mechanism of domoic acid (DA) was investigated using Caco-2 cells. DA is a tricarboxylic amino acid that contains a glutamic acid moiety, and causes deficits in short-term memory by binding to glutamate receptors as an agonist of glutamic acid. Caco-2 cell monolayers cultured on permeable membranes were incubated with 100 µM DA on either the apical or basolateral side, and the transcellular transport of DA was measured. The transcellular transport of DA from the apical to basolateral side was about twofold that in the opposite direction. The transcellular transport of DA from the apical side was optimal at a neutral pH, and was temperature- and Cl(-)-dependent, but was Na(+)-independent. Coincubation of DA with 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), an anion exchange inhibitor, significantly decreased the apical-to-basolateral transport of DA by 48%, and coincubation with probenecid (a non-specific anion transport inhibitor) significantly decreased the transport of DA by 31%. In contrast, coincubation with glutamic acid, succinic acid (a dicarboxylic acid), or citric acid (a tricarboxylic acid) did not decrease the transport of DA. These results suggest that the apical-to-basolateral transport of DA across the Caco-2 cell monolayers is mediated by DIDS-sensitive anion transporters.


Assuntos
Mucosa Intestinal/metabolismo , Ácido Caínico/análogos & derivados , Ácido 4,4'-Di-Isotiocianoestilbeno-2,2'-Dissulfônico/farmacologia , Células CACO-2 , Humanos , Concentração de Íons de Hidrogênio , Absorção Intestinal/efeitos dos fármacos , Intestinos/efeitos dos fármacos , Ácido Caínico/farmacocinética , Temperatura Ambiente
7.
J Agric Food Chem ; 58(23): 12385-91, 2010 Dec 08.
Artigo em Inglês | MEDLINE | ID: mdl-21067177

RESUMO

Naturally produced brominated phenoxyphenols (OH-PBDEs) and phenoxyanisoles (MeO-PBDEs) were analyzed in aquatic plants (16 genera of green, brown, and red algae and angiosperms) collected from Luzon Island, the Philippines. Two brominated phenoxyphenols, 2'-hydroxy-2,3',4,5'-tetrabromodiphenyl ether (2'-OH-BDE68) and 6-hydroxy-2,2',4,4'-tetrabromodiphenyl ether (6-OH-BDE47), were detected in the phenolic fraction of extracts from most of the specimens; Sargassum oligosystum had the highest concentrations (101 ng/g fresh weight (fw)). The corresponding phenoxyanisole, 2'-methoxy-2,3',4,5'-tetrabromodiphenyl ether (2'-MeO-BDE68), was most abundant in Sargassum aff. bataanense (229 ng/g fw), followed by Padina sp., and 6-methoxy-2,2',4,4'-tetrabromodiphenyl ether (6-MeO-BDE47) was predominant in Jania adhaerens (29 ng/g fw). Hydroxy-pentaBDEs, hydroxy-methoxy-tetraBDEs, dihydroxy-tetraBDEs, dihydroxy-tetrabromobiphenyl, and hydroxy-tetrabromodibenzo-p-dioxins were also detected. The present study demonstrates that these aquatic plant species could be an abundant source of OH-PBDEs and MeO-PBDEs found in higher trophic organisms in the Asia-Pacific region.


Assuntos
Clorófitas/metabolismo , Éteres Difenil Halogenados/metabolismo , Magnoliopsida/metabolismo , Feófitas/metabolismo , Rodófitas/metabolismo , Poluentes Químicos da Água/metabolismo , Organismos Aquáticos/química , Organismos Aquáticos/metabolismo , Clorófitas/química , Monitoramento Ambiental , Éteres Difenil Halogenados/análise , Magnoliopsida/química , Feófitas/química , Filipinas , Rodófitas/química , Poluentes Químicos da Água/análise
8.
Proc Natl Acad Sci U S A ; 107(29): 12952-7, 2010 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-20615950

RESUMO

The role of geographic isolation in marine microbial speciation is hotly debated because of the high dispersal potential and large population sizes of planktonic microorganisms and the apparent lack of strong dispersal barriers in the open sea. Here, we show that gene flow between distant populations of the globally distributed, bloom-forming diatom species Pseudo-nitzschia pungens (clade I) is limited and follows a strong isolation by distance pattern. Furthermore, phylogenetic analysis implies that under appropriate geographic and environmental circumstances, like the pronounced climatic changes in the Pleistocene, population structuring may lead to speciation and hence may play an important role in diversification of marine planktonic microorganisms. A better understanding of the factors that control population structuring is thus essential to reveal the role of allopatric speciation in marine microorganisms.


Assuntos
Diatomáceas/genética , Fluxo Gênico/genética , Plâncton/genética , Água do Mar , Alelos , Loci Gênicos/genética , Geografia , Internacionalidade , Filogenia , Análise de Componente Principal , Fatores de Tempo
9.
Chemosphere ; 77(10): 1333-7, 2009 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-19863992

RESUMO

We analyzed the total mercury (T-Hg) and stable isotopes of (13)C and (15)N in the muscle of spiny dogfish (Squalus acanthias) caught off the coast of Japan. The average body length of the female spiny dogfish sampled (94.9+/-20.2 cm, 50.5-131.0 cm, n=40) was significantly larger than that of the males sampled (77.8+/-10.8 cm, 55.5-94.0 cm, n=35), although the ages of the samples were unknown. The T-Hg concentration in the muscle samples rapidly increased after maturity in the females (larger than about 120 cm) and males (larger than about 90 cm), followed by a continued gradual increase. Contamination level of T-Hg in female muscle samples (0.387+/-0.378 microg(wet g)(-1), n=40) was slightly higher than that in male muscle samples (0.316+/-0.202 microg(wet g)(-1), n=35), probably due to the greater longevity of females. In contrast, the contamination level of T-Hg in females smaller than 94.0 cm in length (0.204+/-0.098 microg(wet g)(-1), n=20) was slightly lower than that in the males, probably due to the faster growth rate of females. Although the partial differential(13)C and partial differential(15)N values in the muscle samples increased with an increase in body length, there were no significant differences between the females (-17.2+/-0.4 per thousand and 12.4+/-0.9 per thousand, respectively) and males (-17.3+/-0.4 per thousand and 12.4+/-0.8 per thousand, respectively). A positive correlation was found between partial differential(13)C and partial differential(15)N values, suggesting trophic enrichment due to the growth.


Assuntos
Mercúrio/análise , Músculos/química , Poluentes Químicos da Água/análise , Animais , Monitoramento Ambiental , Feminino , Japão , Masculino , Squalus acanthias
10.
Environ Sci Technol ; 43(7): 2288-94, 2009 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-19452876

RESUMO

Naturally produced halogenated bipyrroles (HBPs) and methoxylated tetraBDEs (MeO-tetraBDEs) are lipophilic and persistent, and therefore may bioaccumulate with higher trophic levels. In this study, the livers of tiger shark (Galeocerdo cuvier) collected from the southern coast of Japan were investigated for size-related bioaccumulation of natural HBPs and MeO-tetraBDEs in comparison with anthropogenic PCBs and PBDEs. Heptachloro-1'-methyl-1,2'-bipyrrole (Cl7-MBP) and hexahalogenated 1,1'-dimethyl-2,2'-bipyrrole (Br4Cl2-DBP) were present at similar concentration ranges (4-4400 ng/g lipid) in the liver and increased with increasing body length. Two MeO-tetraBDEs, 6-methoxy-2,2',4,4'-tetrabromodiphenyl ether(6-MeO-BDE47), and 2'-methoxy-2,3',4,5'-tetrabromodiphenyl ether (2'-MeO-BDE68) were present at 4- to 6-fold higher concentrations (88 and 58 ng/g lipid, respectively) than BDE-47. In mature tiger sharks, 2,2'-dimethoxy-3,3',5,5'-tetrabromobiphenyl (2,2'-diMeO-BB80) was present at a median concentration of 330 ng/g lipid. Concentrations of 6-MeO-BDE47 were positively correlated to body length (P < 0.01), but no such correlation was observed for 2'-MeO-BDE68 and 2,2'-diMeO-BB80. The concentration ratios (patterns) of PBDE-like natural products in tiger sharks were largely different from that found in other species, such as the bull shark (Carcharhinus leucas), the silvertip shark (Carcharhinus albimarginatus), and the sandbar shark (Carcharhinus plumbeus). The present study suggests thatthe concentrations of natural HBPs in the liver are size (age)-dependent whereas MeO-tetraBDEs have species-specific biomagnification potentials.


Assuntos
Halogênios/metabolismo , Hidrocarbonetos Bromados/metabolismo , Pirróis/metabolismo , Tubarões/metabolismo , Animais , Japão , Controle de Qualidade , Especificidade da Espécie
11.
J Phycol ; 44(3): 650-61, 2008 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27041423

RESUMO

We identified and investigated the potential toxicity of oceanic Pseudo-nitzschia species from Ocean Station Papa (OSP), located in a high-nitrate, low-chlorophyll (HNLC) region of the northeast (NE) subarctic Pacific Ocean. Despite their relatively low abundances in the indigenous phytoplankton assemblage, Pseudo-nitzschia species richness is high. The morphometric characteristics of five oceanic Pseudo-nitzschia isolates from at least four species are described using SEM and TEM. The species identified are Pseudo-nitzschia dolorosa Lundholm et Moestrup, P. granii Hasle, P. heimii Manguin, and P. cf. turgidula (Hust.) Hasle. Additional support for the taxonomic classifications based on frustule morphology is provided through the sequencing of the internal transcribed spacer 1 (ITS1) rDNA. Pseudo-nitzschia species identification was also assessed by the construction of ITS1 clone libraries and using automated ribosomal intergenic spacer analysis (ARISA) for environmental samples collected during the Subarctic Ecosystem Response to Iron Enrichment Study (SERIES), conducted in close proximity to OSP in July of 2002. Based on ITS1 sequences, the presence of P. granii, P. heimii, P. cf. turgidula, and at least five other putative, unidentified Pseudo-nitzschia ITS1 variants was confirmed within iron-enriched phytoplankton assemblages at OSP. None of the oceanic isolates produced detectable levels of particulate domoic acid (DA) when in prolonged stationary phase due to silicic acid starvation. The lack of detectable concentrations of DA suggests that either these strains produce very little or no toxin, or that the physiological conditions required to promote particulate DA production were not met and thus differ from their coastal, toxigenic congeners.

12.
Toxicon ; 46(8): 946-53, 2005 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-16289181

RESUMO

In order to obtain more detailed information on the distribution of domoic acid-producing Nitzschia in Asian waters, Nitzschia-like diatoms were isolated primarily from the Philippines and established in culture for analysis by HPLC with fluorescence detection. Out of 58 isolates, 35 Nitzschia-like diatoms from the estuary areas of San Pedro Bay, Tacloban City and Manila Bay showed significant levels of domoic acid production (1.3-5.6pg/cell). These were identified as Nitzschia navis-varingica. Two isolates from the same locality did not produce domoic acid. Of the 21 isolates from Bulacan Estuary, Manila Bay, none produced domoic acid. They did, however, produce two substances that seemed to be domoic acid derivatives. One of the strains was mass cultured and the substances were extracted, purified and analyzed by LC-MS/MS, proton and (13)C NMR, and UV spectra. The produced substances were determined as isodomoic acids A and B. This is the first report of a diatom that produces isodomoic acids A and B as major toxin components.


Assuntos
Diatomáceas/química , Ácido Caínico/análogos & derivados , Toxinas Marinhas/isolamento & purificação , Cromatografia Líquida de Alta Pressão , Primers do DNA , Diatomáceas/ultraestrutura , Ácido Caínico/isolamento & purificação , Espectrometria de Massas , Microscopia Eletrônica de Transmissão , Ressonância Magnética Nuclear Biomolecular , Filipinas , Reação em Cadeia da Polimerase , Especificidade da Espécie , Espectrofotometria Ultravioleta
13.
Biosci Biotechnol Biochem ; 67(2): 388-92, 2003 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-12729005

RESUMO

Several species of microalgae (phytoplankton), 4 species of freshwater algae and 4 species of marine diatoms, were cultured germ-free in the laboratory. The presence of free D-amino acids was verified in these species by a reversed-phase HPLC analysis. D-Aspartate was detected in all the microalgae examined, but D-alanine was only present in the marine diatoms. The D-amino acid content in Asterionella sp. of the marine diatoms increased from the exponential phase to the stationary phase and then decreased to the phase of decline.


Assuntos
Aminoácidos/análise , Eucariotos/química , Fitoplâncton/química , Aminoácidos/química , Cromatografia Líquida de Alta Pressão/métodos , Água Doce , Água do Mar
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