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Lipophilic marine biotoxins azaspiracids (AZAs) are produced by dinoflagellates Azadinium and Amphidoma. Recently, several strains of Azadinium poporum were isolated from Japanese coastal waters. In our present study, AZA analogues in two strains (mdd421 and HM536) of A. poporum were analyzed by several detection techniques on the liquid chromatography-tandem mass spectrometry (LC-MS/MS) and liquid chromatography-quadrupole time of flight mass spectrometry (LC-QTOFMS). The dominant AZA analogue in the Japanese A. poporum strains was AZA2. Other known AZA analogues were AZA11, AZA35, AZA2 methyl ester and AZA2 phosphate ester. Besides these AZAs, thirteen new AZA analogues were discovered in the two strains. A putative AZA analogue (Compound 1) with the smallest molecular weight ever found in nature was also discovered in the two strains. This is the first report describing detailed AZA profiles in Japanese isolates of A. poporum.
Mayu Ozawa; Hajime Uchida; Ryuichi Watanabe; Ryoji Matsushima; Hiroshi Oikawa; Kazuya Takahashi; Mitsunori Iwataki; Toshiyuki Suzuki. Complex profiles of azaspiracid analogues in two culture strains of Azadinium poporum (Amphidomataceae, Dinophyceae) isolated from Japanese coastal waters determined by LC-MS/MS. Toxicon 2021, 199, 145 -155.
AMA StyleMayu Ozawa, Hajime Uchida, Ryuichi Watanabe, Ryoji Matsushima, Hiroshi Oikawa, Kazuya Takahashi, Mitsunori Iwataki, Toshiyuki Suzuki. Complex profiles of azaspiracid analogues in two culture strains of Azadinium poporum (Amphidomataceae, Dinophyceae) isolated from Japanese coastal waters determined by LC-MS/MS. Toxicon. 2021; 199 ():145-155.
Chicago/Turabian StyleMayu Ozawa; Hajime Uchida; Ryuichi Watanabe; Ryoji Matsushima; Hiroshi Oikawa; Kazuya Takahashi; Mitsunori Iwataki; Toshiyuki Suzuki. 2021. "Complex profiles of azaspiracid analogues in two culture strains of Azadinium poporum (Amphidomataceae, Dinophyceae) isolated from Japanese coastal waters determined by LC-MS/MS." Toxicon 199, no. : 145-155.
The consumption of contaminated shellfish with okadaic acid (OA) group of toxins leads to diarrhoeic shellfish poisoning (DSP) characterized by a set of symptoms including nausea, vomiting and diarrhoea. These phycotoxins are Ser/Thr phosphatase inhibitors, which produce hyperphosphorylation in cellular proteins. However, this inhibition does not fully explain the symptomatology reported and other targets could be relevant to the toxicity. Previous studies have indicated a feasible involvement of the nervous system. We performed a set of in vivo approaches to elucidate whether neuropeptide Y (NPY), Peptide YY (PYY) or serotonin (5-HT) was implicated in the early OA-induced diarrhoea. Fasted Swiss female mice were administered NPY, PYY(3–36) or cyproheptadine intraperitoneal prior to oral OA treatment (250 µg/kg). A non-significant delay in diarrhoea onset was observed for NPY (107 µg/kg) and PYY(3–36) (1 mg/kg) pre-treatment. On the contrary, the serotonin antagonist cyproheptadine was able to block (10 mg/kg) or delay (0.1 and 1 mg/kg) diarrhoea onset suggesting a role of 5-HT. This is the first report of the possible involvement of serotonin in OA-induced poisoning.
M. Carmen Louzao; Celia Costas; Paula Abal; Toshiyuki Suzuki; Ryuichi Watanabe; Natalia Vilariño; Cristina Carrera; Andrea Boente-Juncal; Carmen Vale; Mercedes R. Vieytes; Luis M. Botana. Serotonin involvement in okadaic acid-induced diarrhoea in vivo. Archives of Toxicology 2021, 95, 1 -17.
AMA StyleM. Carmen Louzao, Celia Costas, Paula Abal, Toshiyuki Suzuki, Ryuichi Watanabe, Natalia Vilariño, Cristina Carrera, Andrea Boente-Juncal, Carmen Vale, Mercedes R. Vieytes, Luis M. Botana. Serotonin involvement in okadaic acid-induced diarrhoea in vivo. Archives of Toxicology. 2021; 95 (8):1-17.
Chicago/Turabian StyleM. Carmen Louzao; Celia Costas; Paula Abal; Toshiyuki Suzuki; Ryuichi Watanabe; Natalia Vilariño; Cristina Carrera; Andrea Boente-Juncal; Carmen Vale; Mercedes R. Vieytes; Luis M. Botana. 2021. "Serotonin involvement in okadaic acid-induced diarrhoea in vivo." Archives of Toxicology 95, no. 8: 1-17.
Diarrhetic shellfish poisoning (DSP) is caused by the consumption of shellfish contaminated by diarrhetic shellfish toxins (DSTs) such as okadaic acid (OA) and dinophysistoxins (DTXs) produced by some species of dinoflagellates. To prevent the occurrence of human intoxication cases, inspection of DSTs (OA and DTXs) in shellfish is important. An instrumental method using liquid chromatography-tandem mass spectrometry (LC/MS/MS) has been recently employed in Japan for the monitoring of OA and DTXs in shellfish. For such analysis, reference materials (RMs) of OA and DTXs are essential. Demand for the reference materials, especially dinophysistoxin-1 (DTX1), is recently increasing in Japan. Production of the materials has been performed by mass cultivation of a dinoflagellate (Prorocentrum lima) strain that produces DTXs and OA, which indicates that the efficiency of production depends on the toxin production of the strain used. In this study, P. lima complex subclade 1e strain MIO12P was determined to be a high DTX1 producer among the three Japanese strains of the P. lima complex (subclades 1e, 1f, and 1i). It was clarified that the culture medium suitable for toxin production by strain MIO12P was metals mix SWII medium, and the optimal temperature and salinity for toxin production were 25 °C and salinity 30, respectively. The DTX1 yield (1265.3 ng ml−1) of strain MIO12P cultured under the conditions described above was the highest reported worldwide. Prorocentrum lima complex subclade 1e strain MIO12P is expected to be useful for the sustainable production of DTX1 as a source of RMs for chemical and biochemical methods in the future.
Kana Hashimoto; Hajime Uchida; Tomohiro Nishimura; Hiroshi Oikawa; Hiroshi Funaki; Chiho Honma; Haruo Yamaguchi; Toshiyuki Suzuki; Masao Adachi. Determination of optimal culture conditions for toxin production by a Prorocentrum lima complex strain with high diarrhetic shellfish toxins yield. Harmful Algae 2021, 103, 102025 .
AMA StyleKana Hashimoto, Hajime Uchida, Tomohiro Nishimura, Hiroshi Oikawa, Hiroshi Funaki, Chiho Honma, Haruo Yamaguchi, Toshiyuki Suzuki, Masao Adachi. Determination of optimal culture conditions for toxin production by a Prorocentrum lima complex strain with high diarrhetic shellfish toxins yield. Harmful Algae. 2021; 103 ():102025.
Chicago/Turabian StyleKana Hashimoto; Hajime Uchida; Tomohiro Nishimura; Hiroshi Oikawa; Hiroshi Funaki; Chiho Honma; Haruo Yamaguchi; Toshiyuki Suzuki; Masao Adachi. 2021. "Determination of optimal culture conditions for toxin production by a Prorocentrum lima complex strain with high diarrhetic shellfish toxins yield." Harmful Algae 103, no. : 102025.
A novel symmetrical macrocyclic phthalate hexaester (1) and a known macrocyclic phthalate tetraester (2) were isolated during a natural product-exploring program on the cyanobacterium Moorea producens. Their structures were elucidated based on spectroscopic data, including nuclear magnetic resonance and high-resolution mass spectra. In the antibacterial activity test, compounds 1 and 2 showed no bioactivity at the concentrations tested.
Michiya Kamio; Weina Jiang; Hiroki Osada; Masayuki Fukuoka; Hajime Uchida; Ryuichi Watanabe; Toshiyuki Suzuki; Hiroshi Nagai. Isolation and Structure Elucidation of a Novel Symmetrical Macrocyclic Phthalate Hexaester. Symmetry 2021, 13, 361 .
AMA StyleMichiya Kamio, Weina Jiang, Hiroki Osada, Masayuki Fukuoka, Hajime Uchida, Ryuichi Watanabe, Toshiyuki Suzuki, Hiroshi Nagai. Isolation and Structure Elucidation of a Novel Symmetrical Macrocyclic Phthalate Hexaester. Symmetry. 2021; 13 (2):361.
Chicago/Turabian StyleMichiya Kamio; Weina Jiang; Hiroki Osada; Masayuki Fukuoka; Hajime Uchida; Ryuichi Watanabe; Toshiyuki Suzuki; Hiroshi Nagai. 2021. "Isolation and Structure Elucidation of a Novel Symmetrical Macrocyclic Phthalate Hexaester." Symmetry 13, no. 2: 361.
Okadaic acid (OA) and its main structural analogs dinophysistoxin-1 (DTX1) and dinophysistoxin-2 (DTX2) are marine lipophilic phycotoxins distributed worldwide that can be accumulated by edible shellfish and can cause diarrheic shellfish poisoning (DSP). In order to study their toxicokinetics, mice were treated with different doses of OA, DTX1, or DTX2 and signs of toxicity were recorded up to 24 h. Toxin distribution in the main organs from the gastrointestinal tract was assessed by liquid chromatography-mass spectrometry (LC/MS/MS) analysis. Our results indicate a dose-dependency in gastrointestinal absorption of these toxins. Twenty-four hours post-administration, the highest concentration of toxin was detected in the stomach and, in descending order, in the large intestine, small intestine, and liver. There was also a different toxicokinetic pathway between OA, DTX1, and DTX2. When the same toxin doses are compared, more OA than DTX1 is detected in the small intestine. OA and DTX1 showed similar concentrations in the stomach, liver, and large intestine tissues, but the amount of DTX2 is much lower in all these organs, providing information on DSP toxicokinetics for human safety assessment.
M. Carmen Louzao; Paula Abal; Celia Costas; Toshiyuki Suzuki; Ryuichi Watanabe; Natalia Vilariño; Ana M. Botana; Mercedes R. Vieytes; Luis M. Botana. DSP Toxin Distribution across Organs in Mice after Acute Oral Administration. Marine Drugs 2021, 19, 23 .
AMA StyleM. Carmen Louzao, Paula Abal, Celia Costas, Toshiyuki Suzuki, Ryuichi Watanabe, Natalia Vilariño, Ana M. Botana, Mercedes R. Vieytes, Luis M. Botana. DSP Toxin Distribution across Organs in Mice after Acute Oral Administration. Marine Drugs. 2021; 19 (1):23.
Chicago/Turabian StyleM. Carmen Louzao; Paula Abal; Celia Costas; Toshiyuki Suzuki; Ryuichi Watanabe; Natalia Vilariño; Ana M. Botana; Mercedes R. Vieytes; Luis M. Botana. 2021. "DSP Toxin Distribution across Organs in Mice after Acute Oral Administration." Marine Drugs 19, no. 1: 23.
Macroalgal samples were collected from coastal waters in subboreal to subtropical zones in Japan (< 3–30 m depths) and 32 clonal strains of non-motile dinoflagellate-like protists were established. Molecular phylogenetic analyses of the LSU rDNA D1/D2, SSU rDNA, ITS region, and concatenated SSU rDNA + LSU rDNA D1/D2 sequences revealed that the strains nested within the genus Alexandrium. They were separated into three novel phylotypes: Alexandrium spp. type 1, type 2, and type 3. Analysis of the concatenated sequences revealed that the most closely related species for the three phylotypes was A. ostenfeldii. Most cells from strains of the three phylotypes were non-motile and hemispherical to spherical in shape. The average diameters of the non-motile cells were between 35 and 39 µm. Type 1 and type 2 were widely distributed in Japan from the temperate to subtropical zones, whereas type 3 was restricted to the temperate zone. Furthermore, type 2 was widespread from shallow to deep waters, whereas type 1 and type 3 were restricted to deep waters. Growth experiments in strains belonging to the three phylotypes revealed that the occurrence ratios of motile cells were very low (≤ 1.1% of the total cells). The production of paralytic shellfish poisoning toxins, tetrodotoxin, and cyclic imines was assessed in strains belonging to the three phylotypes by LC/MS/MS analysis. The strains did not produce any of the toxins tested. The strains of the three phylotypes showed lethal toxicity to mice by intraperitoneal administration. To the best of our knowledge, this is the first study to report the existence of Alexandrium associated with marine macroalgae from Japan.
Tomohiro Nishimura; Yuki Kuribara; Ryo Fukuzawa; Katsuya Mimura; Hiroshi Funaki; Kouki Tanaka; Ryuichi Watanabe; Hajime Uchida; Toshiyuki Suzuki; Masao Adachi. First report of Alexandrium (Dinophyceae) associated with marine macroalgae off Japan: Diversity, distribution, and toxicity. Harmful Algae 2020, 104, 101924 .
AMA StyleTomohiro Nishimura, Yuki Kuribara, Ryo Fukuzawa, Katsuya Mimura, Hiroshi Funaki, Kouki Tanaka, Ryuichi Watanabe, Hajime Uchida, Toshiyuki Suzuki, Masao Adachi. First report of Alexandrium (Dinophyceae) associated with marine macroalgae off Japan: Diversity, distribution, and toxicity. Harmful Algae. 2020; 104 ():101924.
Chicago/Turabian StyleTomohiro Nishimura; Yuki Kuribara; Ryo Fukuzawa; Katsuya Mimura; Hiroshi Funaki; Kouki Tanaka; Ryuichi Watanabe; Hajime Uchida; Toshiyuki Suzuki; Masao Adachi. 2020. "First report of Alexandrium (Dinophyceae) associated with marine macroalgae off Japan: Diversity, distribution, and toxicity." Harmful Algae 104, no. : 101924.
An extensively N-methylated linear nonapeptide heptavalinamide A (1) was isolated from the marine cyanobacterium Symploca sp. collected at Kabira Reef of Ishigaki Island, Okinawa. The amino acid sequence of 1 was assigned by interpretation of 2D NMR and MS/MS data. The absolute configurations of the constituent amino acids were determined by the application of Marfey’s method. A method to assign the configuration of N,N-dimethylvaline by LCMS is discussed.
Rei Suo; Ryuichi Watanabe; Kentaro Takada; Toshiyuki Suzuki; Hiroshi Oikawa; Shiro Itoi; Haruo Sugita; Shigeki Matsunaga. Heptavalinamide A, an Extensively N-Methylated Linear Nonapeptide from a Cyanobacterium Symploca sp. and Development of a Highly Sensitive Analysis of N,N-Dimethylvaline by LCMS. Organic Letters 2020, 22, 1254 -1258.
AMA StyleRei Suo, Ryuichi Watanabe, Kentaro Takada, Toshiyuki Suzuki, Hiroshi Oikawa, Shiro Itoi, Haruo Sugita, Shigeki Matsunaga. Heptavalinamide A, an Extensively N-Methylated Linear Nonapeptide from a Cyanobacterium Symploca sp. and Development of a Highly Sensitive Analysis of N,N-Dimethylvaline by LCMS. Organic Letters. 2020; 22 (4):1254-1258.
Chicago/Turabian StyleRei Suo; Ryuichi Watanabe; Kentaro Takada; Toshiyuki Suzuki; Hiroshi Oikawa; Shiro Itoi; Haruo Sugita; Shigeki Matsunaga. 2020. "Heptavalinamide A, an Extensively N-Methylated Linear Nonapeptide from a Cyanobacterium Symploca sp. and Development of a Highly Sensitive Analysis of N,N-Dimethylvaline by LCMS." Organic Letters 22, no. 4: 1254-1258.
In the present study, the abundance of Prorocentrum and the molecular phylogeny, distribution, and DST production of P. lima complex and P. caipirignum in Japan were investigated. First, the cell densities of Prorocentrum were assessed from the temperate to subtropical zones in Japan between 2014 and 2018. The cell density in the subtropical zone [19.0 ± 40.2 cells/g wet weight (ww) algae] was significantly higher than that in the temperate zone (1.4 ± 3.4 cells/g ww algae). A total of 244 clonal strains were established from the temperate and subtropical zones. Phylogenetic analyses based on the large-subunit ribosomal DNA D1/D2 revealed that the strains were separated into four species/species complex/phylotypes (P. limacomplex, P. caipirignum, and new phylotypes Prorocentrum spp. types 1 and 2). The strains of P. lima complex could be separated into two clades (1 and 3). Furthermore, the strains of clades 1 and 3 could be separated into nine subclades (1a, 1c, 1d, 1e, 1f, 1 g, 1 h, 1i, and 1 j) and three subclades (3a, 3b, and 3c), respectively. The strains of P. caipirignum were separated into two subclades (b and e). Each phylotype/subclade showed a unique distribution pattern in Japan: P. lima complex subclades 1a, 1c, and 3a and P. caipirignum subclades b and e were widespread from the temperate to subtropical zones. On the other hand, P. lima complex subclades 1e and 1i were restricted to the temperate zone, and P. lima complex subclades 1d, 1f, 1 g, 1 h, 1 j, 3b, and 3c and Prorocentrum spp. types 1 and 2 were restricted to the subtropical zone. Furthermore, the DST production of the 243 clonal strains was assessed by LC/MS/MS analysis. The results revealed that all strains produced okadaic acid (OA) and that the OA contents of P. lima complex subclades 1d and 1f, P. caipirignum subclades b and e, and Prorocentrum sp. type 2 tended to be higher than those of the other subclades. While P. lima complex subclades 1a, 1e, 1f, and 1i produced DTX1, the other phylotype/subclades produced either no or low quantities of DTX1. A strain of P. lima complex subclade 1e showed the highest OA and DTX1 contents (55.27 and 70.73 pg/cell, respectively) in the world. These results suggest that there are potential risks for DST accumulation in benthic animals in Japan.
Tomohiro Nishimura; Hajime Uchida; Ryoko Noguchi; Hiroshi Oikawa; Toshiyuki Suzuki; Hiroshi Funaki; Chiho Ihara; Kyoko Hagino; Shingo Arimitsu; Yuta Tanii; Shota Abe; Kana Hashimoto; Katsuya Mimura; Kouki Tanaka; Ippei Yanagida; Masao Adachi. Abundance of the benthic dinoflagellate Prorocentrum and the diversity, distribution, and diarrhetic shellfish toxin production of Prorocentrum lima complex and P. caipirignum in Japan. Harmful Algae 2019, 96, 101687 .
AMA StyleTomohiro Nishimura, Hajime Uchida, Ryoko Noguchi, Hiroshi Oikawa, Toshiyuki Suzuki, Hiroshi Funaki, Chiho Ihara, Kyoko Hagino, Shingo Arimitsu, Yuta Tanii, Shota Abe, Kana Hashimoto, Katsuya Mimura, Kouki Tanaka, Ippei Yanagida, Masao Adachi. Abundance of the benthic dinoflagellate Prorocentrum and the diversity, distribution, and diarrhetic shellfish toxin production of Prorocentrum lima complex and P. caipirignum in Japan. Harmful Algae. 2019; 96 ():101687.
Chicago/Turabian StyleTomohiro Nishimura; Hajime Uchida; Ryoko Noguchi; Hiroshi Oikawa; Toshiyuki Suzuki; Hiroshi Funaki; Chiho Ihara; Kyoko Hagino; Shingo Arimitsu; Yuta Tanii; Shota Abe; Kana Hashimoto; Katsuya Mimura; Kouki Tanaka; Ippei Yanagida; Masao Adachi. 2019. "Abundance of the benthic dinoflagellate Prorocentrum and the diversity, distribution, and diarrhetic shellfish toxin production of Prorocentrum lima complex and P. caipirignum in Japan." Harmful Algae 96, no. : 101687.
Tetrodotoxin and its analogues are the causative toxins of pufferfish poisoning. Tetrodotoxin was recently detected in bivalve mollusks collected in New Zealand and Europe, highlighting the need to include tetrodotoxin in monitoring programs for bivalves by instrumental methods. In the present study tetrodotoxin and its analogues in commercially available tetrodotoxin reagents were quantitated accurately by quantitative 1H-nuclear magnetic resonance (qNMR) spectroscopy. The results were applied to estimate relative molar responses of tetrodotoxin and its analogues in hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC/MS/MS). All four components (tetrodotoxin hemilactal form (1), tetrodotoxin 10,7-lactone form (2), 4-epi-tetrodotoxin (3) and 4,9-anhydrotetrodotoxin (4)) generated by equilibrating tetrodotoxin in aqueous solution were prepared as a mixture. From the HSQC spectrum of the mixture, the separated signals derived from three components, excluding 1, were selected and used for the quantitation. In addition, the relative molar responses of 3 and 4 on HILIC/MS/MS were calculated to be 0.73 and 0.46, respectively. These values could be useful for quantitation of 3 and 4 using tetrodotoxin standard by the HILIC/MS/MS. Our results also indicate that qNMR is useful for preparation of tetrodotoxin certified reference material (CRM).
Ryuichi Watanabe; Masato Tanioka; Hajime Uchida; Ryoji Matsushima; Hiroshi Oikawa; Masahiro Matsumiya; Mari Yotsu-Yamashita; Toshiyuki Suzuki. Quantitation of Tetrodotoxin and Its Analogues with a Combination of Liquid Chromatography–Tandem Mass Spectrometry and Quantitative 1H-NMR Spectroscopy. Journal of Agricultural and Food Chemistry 2019, 67, 12911 -12917.
AMA StyleRyuichi Watanabe, Masato Tanioka, Hajime Uchida, Ryoji Matsushima, Hiroshi Oikawa, Masahiro Matsumiya, Mari Yotsu-Yamashita, Toshiyuki Suzuki. Quantitation of Tetrodotoxin and Its Analogues with a Combination of Liquid Chromatography–Tandem Mass Spectrometry and Quantitative 1H-NMR Spectroscopy. Journal of Agricultural and Food Chemistry. 2019; 67 (46):12911-12917.
Chicago/Turabian StyleRyuichi Watanabe; Masato Tanioka; Hajime Uchida; Ryoji Matsushima; Hiroshi Oikawa; Masahiro Matsumiya; Mari Yotsu-Yamashita; Toshiyuki Suzuki. 2019. "Quantitation of Tetrodotoxin and Its Analogues with a Combination of Liquid Chromatography–Tandem Mass Spectrometry and Quantitative 1H-NMR Spectroscopy." Journal of Agricultural and Food Chemistry 67, no. 46: 12911-12917.
Saxitoxin (STX) and its analogues produced by toxic dinoflagellates accumulate in bivalves, and routine monitoring of bivalves is important to prevent cases of human poisoning. In this study, we describe a rapid detection method for the analysis of STXs using ultra-performance liquid chromatography with post-column fluorescent detection and to investigate water depths and sampling points optimal for shellfish toxin monitoring. Cultured scallops (Mizuhopecten yessoensis) and mussels (Mytilus galloprovincialis) collected from various water depths and sampling points were used in this study. Irrespective of bivalve species, toxin concentrations in bivalves were lower at deeper water depths. The toxin concentrations of bivalves did not differ greatly when bivalves were collected from the same bay. Although the levels of contamination of bivalves with STXs can depend on various environmental and geographical factors, our findings are useful for formulating a sampling protocol for the prevention of harvesting contaminated shellfish.
Ryuichi Watanabe; Makoto Kanamori; Hidetsugu Yoshida; Yutaka Okumura; Hajime Uchida; Ryoji Matsushima; Hiroshi Oikawa; Toshiyuki Suzuki. Development of Ultra-Performance Liquid Chromatography with Post-Column Fluorescent Derivatization for the Rapid Detection of Saxitoxin Analogues and Analysis of Bivalve Monitoring Samples. Toxins 2019, 11, 573 .
AMA StyleRyuichi Watanabe, Makoto Kanamori, Hidetsugu Yoshida, Yutaka Okumura, Hajime Uchida, Ryoji Matsushima, Hiroshi Oikawa, Toshiyuki Suzuki. Development of Ultra-Performance Liquid Chromatography with Post-Column Fluorescent Derivatization for the Rapid Detection of Saxitoxin Analogues and Analysis of Bivalve Monitoring Samples. Toxins. 2019; 11 (10):573.
Chicago/Turabian StyleRyuichi Watanabe; Makoto Kanamori; Hidetsugu Yoshida; Yutaka Okumura; Hajime Uchida; Ryoji Matsushima; Hiroshi Oikawa; Toshiyuki Suzuki. 2019. "Development of Ultra-Performance Liquid Chromatography with Post-Column Fluorescent Derivatization for the Rapid Detection of Saxitoxin Analogues and Analysis of Bivalve Monitoring Samples." Toxins 11, no. 10: 573.
The identification and quantification of okadaic acid (OA)/dinophysistoxin (DTX) analogues and pectenotoxins (PTXs) in Dinophysis samples collected from coastal locations around Japan were evaluated by liquid chromatography mass spectrometry. The species identified and analyzed included Dinophysis fortii, D. acuminata, D. mitra (Phalacroma mitra), D. norvegica, D. infundibulus, D. tripos, D. caudata, D. rotundata (Phalacroma rotundatum), and D. rudgei. The dominant toxin found in D. acuminata was PTX2 although some samples contained DTX1 as a minor toxin. D. acuminata specimens isolated from the southwestern regions (Takada and Hiroshima) showed characteristic toxin profiles, with only OA detected in samples collected from Takada. In contrast, both OA and DTX1, in addition to a larger proportion of PTX2, were detected in D. acuminata from Hiroshima. D. fortii showed a toxin profile dominated by PTX2 although this species had higher levels of DTX1 than D. acuminata. OA was detected as a minor toxin in some D. fortii samples collected from Yakumo, Noheji, and Hakata. PTX2 was also the dominant toxin found among other Dinophysis species analyzed, such as D. norvegica, D. tripos, and D. caudata, although some pooled picked cells of these species contained trace levels of OA or DTX1. The results obtained in this study re-confirm that cellular toxin content and profiles are different even among strains of the same species.
Hajime Uchida; Ryuichi Watanabe; Ryoji Matsushima; Hiroshi Oikawa; Satoshi Nagai; Takashi Kamiyama; Katsuhisa Baba; Akira Miyazono; Yuki Kosaka; Shinnosuke Kaga; Yukihiko Matsuyama; Toshiyuki Suzuki. Toxin Profiles of Okadaic Acid Analogues and Other Lipophilic Toxins in Dinophysis from Japanese Coastal Waters. Toxins 2018, 10, 457 .
AMA StyleHajime Uchida, Ryuichi Watanabe, Ryoji Matsushima, Hiroshi Oikawa, Satoshi Nagai, Takashi Kamiyama, Katsuhisa Baba, Akira Miyazono, Yuki Kosaka, Shinnosuke Kaga, Yukihiko Matsuyama, Toshiyuki Suzuki. Toxin Profiles of Okadaic Acid Analogues and Other Lipophilic Toxins in Dinophysis from Japanese Coastal Waters. Toxins. 2018; 10 (11):457.
Chicago/Turabian StyleHajime Uchida; Ryuichi Watanabe; Ryoji Matsushima; Hiroshi Oikawa; Satoshi Nagai; Takashi Kamiyama; Katsuhisa Baba; Akira Miyazono; Yuki Kosaka; Shinnosuke Kaga; Yukihiko Matsuyama; Toshiyuki Suzuki. 2018. "Toxin Profiles of Okadaic Acid Analogues and Other Lipophilic Toxins in Dinophysis from Japanese Coastal Waters." Toxins 10, no. 11: 457.
There are several examples of marine organisms whose metabolic profiles differ among conspecifics inhabiting the same region. We have analyzed the metabolic profile of each colony of a Theonella swinhoei marine sponge with a yellow interior and noticed the patchy distribution of one metabolite. This compound was isolated and its structure was studied by a combination of spectrometric analyses and chemical degradation, showing it to be a congener in the theonellamide class of bicyclic peptides. Theonellamides had previously been isolated by us only from T. swinhoei with a white interior and not from those with a yellow interior.
Kazuya Fukuhara; Kentaro Takada; Ryuichi Watanabe; Toshiyuki Suzuki; Shigeru Okada; Shigeki Matsunaga. Colony-wise Analysis of a Theonella swinhoei Marine Sponge with a Yellow Interior Permitted the Isolation of Theonellamide I. Journal of Natural Products 2018, 81, 2595 -2599.
AMA StyleKazuya Fukuhara, Kentaro Takada, Ryuichi Watanabe, Toshiyuki Suzuki, Shigeru Okada, Shigeki Matsunaga. Colony-wise Analysis of a Theonella swinhoei Marine Sponge with a Yellow Interior Permitted the Isolation of Theonellamide I. Journal of Natural Products. 2018; 81 (11):2595-2599.
Chicago/Turabian StyleKazuya Fukuhara; Kentaro Takada; Ryuichi Watanabe; Toshiyuki Suzuki; Shigeru Okada; Shigeki Matsunaga. 2018. "Colony-wise Analysis of a Theonella swinhoei Marine Sponge with a Yellow Interior Permitted the Isolation of Theonellamide I." Journal of Natural Products 81, no. 11: 2595-2599.
Ciguatera fish poisoning (CFP) is a type of food poisoning caused by the consumption of a variety of toxic ciguatera fish species in the tropical and subtropical waters. Although there have been a large number of suspected CFP cases in the Southeast Asian countries, few were confirmed with causative ciguatoxins (CTXs), and reliable information on the symptoms still remains rather limited. In the present study, CTXs in red snapper Lutjanus bohar, implicated in two suspected CFP cases in Vietnam in 2014 and 2016, were determined by use of the single-quadrupole selected ion monitoring (SIM) liquid chromatography/mass spectrometry (LC/MS). Ciguatoxin-1B (CTX-1B), 54-deoxyCTX-1B, and 52-epi-54-deoxyCTX-1B were detected in the red snapper by our LC/MS method. Moreover, CTX-1B, 54-deoxyCTX-1B, and 52-epi-54-deoxyCTX-1B were further identified by the time of flight (TOF) LC/MS with the exact mass spectrum. The CTX profile of the red snapper in Vietnam is similar to those of ciguatera fish from Australia, Okinawa Islands in Japan, Kiribati, and Hong Kong. This is the first comprehensive report unambiguously identifying the causative toxins in fish implicated with reliable information on the poisoning symptoms in CFP in Vietnam and/or Southeast Asian countries.
Dao Viet Ha; Aya Uesugi; Hajime Uchida; Pham Xuan Ky; Dang Quoc Minh; Ryuichi Watanabe; Ryoji Matsushima; Hiroshi Oikawa; Satoshi Nagai; Mitsunori Iwataki; Yasuwo Fukuyo; Toshiyuki Suzuki. Identification of Causative Ciguatoxins in Red Snappers Lutjanus bohar Implicated in Ciguatera Fish Poisonings in Vietnam. Toxins 2018, 10, 420 .
AMA StyleDao Viet Ha, Aya Uesugi, Hajime Uchida, Pham Xuan Ky, Dang Quoc Minh, Ryuichi Watanabe, Ryoji Matsushima, Hiroshi Oikawa, Satoshi Nagai, Mitsunori Iwataki, Yasuwo Fukuyo, Toshiyuki Suzuki. Identification of Causative Ciguatoxins in Red Snappers Lutjanus bohar Implicated in Ciguatera Fish Poisonings in Vietnam. Toxins. 2018; 10 (10):420.
Chicago/Turabian StyleDao Viet Ha; Aya Uesugi; Hajime Uchida; Pham Xuan Ky; Dang Quoc Minh; Ryuichi Watanabe; Ryoji Matsushima; Hiroshi Oikawa; Satoshi Nagai; Mitsunori Iwataki; Yasuwo Fukuyo; Toshiyuki Suzuki. 2018. "Identification of Causative Ciguatoxins in Red Snappers Lutjanus bohar Implicated in Ciguatera Fish Poisonings in Vietnam." Toxins 10, no. 10: 420.
Diarrhetic shellfish toxins (DSTs) are a group of phycotoxins that include okadaic acid (OA)/dinophysistoxin (DTX) analogues. At present, detailed data on the distribution of DST is insufficient, and studies of the appropriate sample sizes are lacking. This study investigated the DST frequency distribution in scallops and mussels by liquid chromatography-tandem mass spectrometry (LC/MS/MS) and a resampling analysis of existing data was carried out. The DST population-interval and the necessary sample size were also estimated. DSTs are localized in the scallop digestive-gland, and the DST concentrations in scallops were water-depth-dependent. DST concentrations in scallops and mussels showed normal distributions, but mussels tended to contain more DSTs than scallops. In the statistical resampling analysis of the acquired data on scallops and mussels, especially that using the bootstrap method, sample size was difficult to estimate when the DST variation was large. Although the DST population-interval could be statistically estimated from the sample standard deviation of three samples, the sample size corresponded to the risk management level, and the use of 13 or more samples was preferable. The statistical methods used here to analyze individual contents and estimate population content-intervals could be applied in various situations and for shellfish toxins other than DSTs.
Ryoji Matsushima; Hajime Uchida; Ryuichi Watanabe; Hiroshi Oikawa; Izumi Oogida; Yuki Kosaka; Makoto Kanamori; Tatsuro Akamine; Toshiyuki Suzuki. Anatomical Distribution of Diarrhetic Shellfish Toxins (DSTs) in the Japanese Scallop Patinopecten yessoensis and Individual Variability in Scallops and Mytilus edulis Mussels: Statistical Considerations. Toxins 2018, 10, 395 .
AMA StyleRyoji Matsushima, Hajime Uchida, Ryuichi Watanabe, Hiroshi Oikawa, Izumi Oogida, Yuki Kosaka, Makoto Kanamori, Tatsuro Akamine, Toshiyuki Suzuki. Anatomical Distribution of Diarrhetic Shellfish Toxins (DSTs) in the Japanese Scallop Patinopecten yessoensis and Individual Variability in Scallops and Mytilus edulis Mussels: Statistical Considerations. Toxins. 2018; 10 (10):395.
Chicago/Turabian StyleRyoji Matsushima; Hajime Uchida; Ryuichi Watanabe; Hiroshi Oikawa; Izumi Oogida; Yuki Kosaka; Makoto Kanamori; Tatsuro Akamine; Toshiyuki Suzuki. 2018. "Anatomical Distribution of Diarrhetic Shellfish Toxins (DSTs) in the Japanese Scallop Patinopecten yessoensis and Individual Variability in Scallops and Mytilus edulis Mussels: Statistical Considerations." Toxins 10, no. 10: 395.
Harmful algal blooms (HAB) are an ancient and natural phenomena that generally reflects the monospecific, and on rare occasions, the multispecific outgrowth of microalgae in marine coastal areas, estuaries, open waters and freshwater environments. The bloom of several species of HAB are triggered by a complex variety of environmental factors and cause mild to severe impacts on aquatic organisms and human health.
Leila Basti; Kiyohito Nagai; Jiyoji Go; Keita Higuchi; Sho Okano; Tatsuya Oda; Toshiyuki Suzuki; Satoshi Nagai. The Global Phenomena of Harmful Algal Blooms (HAB): Environmental and Socioeconomic Impacts. Plant-Microbes-Engineered Nano-particles (PM-ENPs) Nexus in Agro-Ecosystems 2018, 1717 -1718.
AMA StyleLeila Basti, Kiyohito Nagai, Jiyoji Go, Keita Higuchi, Sho Okano, Tatsuya Oda, Toshiyuki Suzuki, Satoshi Nagai. The Global Phenomena of Harmful Algal Blooms (HAB): Environmental and Socioeconomic Impacts. Plant-Microbes-Engineered Nano-particles (PM-ENPs) Nexus in Agro-Ecosystems. 2018; ():1717-1718.
Chicago/Turabian StyleLeila Basti; Kiyohito Nagai; Jiyoji Go; Keita Higuchi; Sho Okano; Tatsuya Oda; Toshiyuki Suzuki; Satoshi Nagai. 2018. "The Global Phenomena of Harmful Algal Blooms (HAB): Environmental and Socioeconomic Impacts." Plant-Microbes-Engineered Nano-particles (PM-ENPs) Nexus in Agro-Ecosystems , no. : 1717-1718.
An adequate supply of standard reference material for paralytic shellfish toxins (PSTs) is critical for the accurate chemical quantification using high performance liquid chromatography (HPLC) with fluorescent detection, liquid chromatography-tandem mass spectrometry (LC-MS/MS), biological analysis of these toxins using enzyme-linked immunosorbent assay (ELISA), and immunochromatography. Large batch cultivation for the chain forming species G. catenatum, producers of PSTs of N-sulfocarbamoyl-11-hydroxysulfate toxins (C1 and C2), gonyautoxin 5 (GTX5) and gonyautoxin 6 (GTX6), was investigated using 10 L round-bottom flasks with aeration for the production of GTX5 and GTX6. Aeration rates of 200 mL/min and 500 mL/min were compared, demonstrating that the 500 mL/min aeration rate was adequate to eliminate aggregation of cells. The highest cell density of G. catenatum in 500 mL/min aeration treatment was 9,878 ± 2,617 cells/ml on day 28. Total toxin yield during 10 L cultivation with 500 mL/min aeration was calculated at 30.9 ± 3.6 µmol on day 25, with GTX5 and GTX6 calculated at 3.9 ± 0.7 µmol and 11.4 ± 1.4 µmol, respectively. This simple aeration method will contribute to the more efficient production of PST reference materials.
Hiroshi Oikawa; Ryuichi Watanabe; Ryoji Matsushima; Toshiyuki Suzuki. Large-scale Cultivation of Gymnodinium Catenatum for Paralytic Shellfish Poisoning Toxin Standards. Food Safety 2018, 6, 83 -87.
AMA StyleHiroshi Oikawa, Ryuichi Watanabe, Ryoji Matsushima, Toshiyuki Suzuki. Large-scale Cultivation of Gymnodinium Catenatum for Paralytic Shellfish Poisoning Toxin Standards. Food Safety. 2018; 6 (2):83-87.
Chicago/Turabian StyleHiroshi Oikawa; Ryuichi Watanabe; Ryoji Matsushima; Toshiyuki Suzuki. 2018. "Large-scale Cultivation of Gymnodinium Catenatum for Paralytic Shellfish Poisoning Toxin Standards." Food Safety 6, no. 2: 83-87.
Diarrhetic shellfish toxins (DST) are a group of phycotoxins that include Okadaic acid (OA) and structurally related toxins. In Japan, the regulatory limit of DST in shellfish for human consumption is a total OA equivalent of 0.16 mg per kg of edible tissue. Distribution and individual differences of DST in scallops collected in Aomori Prefecture were investigated. Fourteen to 20 individual scallops were divided into hepatopancreas, gonads, mantles, gills, adductor muscles, and the concentrations of diarrhetic shellfish poisoning (DSP) in each tissue were quantified by LC/MS/MS after hydrolysis. The dominant toxin in the scallops was Dinophysis toxin 1 (DTX1). More than 97% of the observed DTX1 in the scallop tissue was detected in the hepatopancreas and the average level of DTX1 was higher in mussels than the scallops. The number of individual scallops or mussels required to correctly reflect the DTX1 content of a sample group was estimated by resampling. In scallops, using 10 individuals fell within ± 20% of 30 individual's average with a probability of 99.8%. On the other hand, in the blue mussel, an average of 19 individuals fell within ± 20% of 30 individual's average with 98% probability. In addition, the analysis of the DST in ascidians collected from Miyagi Prefecture was carried out. The muscles, gills, hepatopancreas and intestines were analyzed. High concentration of both DTX1 and OA were detected in the hepatopancreas after hydrolysis. Low levels of DST were detected from other tissues, indicating that DST are primarily accumulated in the hepatopancreas in the ascidians.
Ryoji Matsushima; Hajime Uchida; Ryuichi Watanabe; Hiroshi Oikawa; Yuki Kosaka; Toru Tanabe; Toshiyuki Suzuki. Distribution of Diarrhetic Shellfish Toxins in Mussels, Scallops, and Ascidian. Food Safety 2018, 6, 101 -106.
AMA StyleRyoji Matsushima, Hajime Uchida, Ryuichi Watanabe, Hiroshi Oikawa, Yuki Kosaka, Toru Tanabe, Toshiyuki Suzuki. Distribution of Diarrhetic Shellfish Toxins in Mussels, Scallops, and Ascidian. Food Safety. 2018; 6 (2):101-106.
Chicago/Turabian StyleRyoji Matsushima; Hajime Uchida; Ryuichi Watanabe; Hiroshi Oikawa; Yuki Kosaka; Toru Tanabe; Toshiyuki Suzuki. 2018. "Distribution of Diarrhetic Shellfish Toxins in Mussels, Scallops, and Ascidian." Food Safety 6, no. 2: 101-106.
Toru Miura; Naoki Sugimoto; Ryuichi Watanabe; Takako Suematsu; Yoichiro Takayanagi; Yoshinobu Ito; Naoki Saito; Ryuichi Sawa; Tsuyoshi Kato; Yoshinori Fujimine; Ryo Koike; Yuko Ohfuku; Yuko Yamada; Hiroaki Utsumi; Toshiyuki Suzuki. Evaluation for Standardization of 1H Quantitative NMR Spectroscopy by Round Robin Test. YAKUGAKU ZASSHI 2017, 137, 1543 -1553.
AMA StyleToru Miura, Naoki Sugimoto, Ryuichi Watanabe, Takako Suematsu, Yoichiro Takayanagi, Yoshinobu Ito, Naoki Saito, Ryuichi Sawa, Tsuyoshi Kato, Yoshinori Fujimine, Ryo Koike, Yuko Ohfuku, Yuko Yamada, Hiroaki Utsumi, Toshiyuki Suzuki. Evaluation for Standardization of 1H Quantitative NMR Spectroscopy by Round Robin Test. YAKUGAKU ZASSHI. 2017; 137 (12):1543-1553.
Chicago/Turabian StyleToru Miura; Naoki Sugimoto; Ryuichi Watanabe; Takako Suematsu; Yoichiro Takayanagi; Yoshinobu Ito; Naoki Saito; Ryuichi Sawa; Tsuyoshi Kato; Yoshinori Fujimine; Ryo Koike; Yuko Ohfuku; Yuko Yamada; Hiroaki Utsumi; Toshiyuki Suzuki. 2017. "Evaluation for Standardization of 1H Quantitative NMR Spectroscopy by Round Robin Test." YAKUGAKU ZASSHI 137, no. 12: 1543-1553.
Toshiyuki Suzuki; Dao Viet Ha; Aya Uesugi; Hajime Uchida. Analytical challenges to ciguatoxins. Current Opinion in Food Science 2017, 18, 37 -42.
AMA StyleToshiyuki Suzuki, Dao Viet Ha, Aya Uesugi, Hajime Uchida. Analytical challenges to ciguatoxins. Current Opinion in Food Science. 2017; 18 ():37-42.
Chicago/Turabian StyleToshiyuki Suzuki; Dao Viet Ha; Aya Uesugi; Hajime Uchida. 2017. "Analytical challenges to ciguatoxins." Current Opinion in Food Science 18, no. : 37-42.
Chemical analysis of the hydrophilic fraction from marine cyanobacterium Moorea producens extracts led to the isolation of five new indole derivatives (1-5). So far, 2-formyl-4,5,6,7-tetrahydroindole has been reported only for 6 from the nature, consequently compounds 1-5 were the second representatives of this class. Cytotoxicity, diatom growth inhibition, and antibacterial activity tests for compounds 1-5 showed no bioactivity at the concentration tested.
Weina Jiang; Yingyue Bu; Mioko Kawaguchi; Hiroki Osada; Masayuki Fukuoka; Hajime Uchida; Ryuichi Watanabe; Toshiyuki Suzuki; Hiroshi Nagai. Five new indole derivatives from the cyanobacterium Moorea producens. Phytochemistry Letters 2017, 22, 163 -166.
AMA StyleWeina Jiang, Yingyue Bu, Mioko Kawaguchi, Hiroki Osada, Masayuki Fukuoka, Hajime Uchida, Ryuichi Watanabe, Toshiyuki Suzuki, Hiroshi Nagai. Five new indole derivatives from the cyanobacterium Moorea producens. Phytochemistry Letters. 2017; 22 ():163-166.
Chicago/Turabian StyleWeina Jiang; Yingyue Bu; Mioko Kawaguchi; Hiroki Osada; Masayuki Fukuoka; Hajime Uchida; Ryuichi Watanabe; Toshiyuki Suzuki; Hiroshi Nagai. 2017. "Five new indole derivatives from the cyanobacterium Moorea producens." Phytochemistry Letters 22, no. : 163-166.