Welcome to our laboratory!

We started our laboratory April, 2004 with new group members. Our major interest is in the chemistry and biochemistry of natural products.

Especially, we are studying on natural toxins from marine animals and organisms. 

Current research projects:

1. Tetrodotoxin (puffer fish toxin): Origin, Biosynthesis, Natural analogues, Analytical methods (LC/MS), Binding model to Na+ channel, Binding protein in puffer fish, Resistant systems against toxins, Metabolism.

2. Okadaic acid : Binding proteins from the sponge Halichondria okadai  

3. Paralytic shellfish poisoning (Saxitoxin analogues): Biosynthesis, Analytical methods, Dynamics

4. Amnesic shellfish poisoning (Domoic acids): Biosynthesis, Natural analogues

5. Electrophysiological study of mode of action of bioactive Natural Products.

6. Seaweed toxins (polycavernoside A) :  Isolation and the structures of congeners, Origin, Analytical methods, Pharmacology

7. Bioactive compounds from marine animals : isolation, structure elucidation and biological activities of the novel compounds.

8. Toxins from amphibians : tetrodotoxin and its congeners, and zetekitoxin (an analogue of saxitoxin)

Members

Professor : Mari Yotsu-Yamashita, Ph.D. {publication list: see bellow}

TEL/FAX 81-22-757-4425 Email: mari.yamashita.c1@[please add tohoku.ac.jp after @]

Associate professor: Keiichi Konoki, Ph.D. {publication list: see bellow} 

Email:keiichi.konoki.b2@ [please add tohoku.ac.jp after @]

Assistant professor: Yuko Cho, Ph.D. {publication list: see bellow} 

Email: yuko.cho.a4@   [please add tohoku.ac.jp after @]

Associate professor (Frontier Research Institute for Interdisciplinary Science (FRIS), Creative Interdisciplinary Research Division)): 

Yuta Kudo, Ph.D. {publication list: see bellow} 

TEL 81-22-757-4427 FAX 81-22-757-4425 Email: yuta.kudo.d5@   [please add tohoku.ac.jp after @]

Graduate students:

Ryosuke Hirozumi (D3) JST spring fellow

Ranmaru Matsui (M2)

Masaki Mochizuki (M2)

Takumi Hasegawa (M2)

Masashi Gamo (M1)

Ayami Sato (M1)

Yuto Yoshida (M1)

Under graduate students:

Natsumi Takahara (B4)

Shugo Horie (B4)

Yuya Yoshida (B4)

Runa Yonekura (B4)

Publication list (1999-)   *corresponding author

Steffaney Wood-Rocca, Nicholas Allsing, Yasuhiro Ashida, Masaki Mochizuki, Malia Moore, Zoltán Füssy, Yuichi Kotaki, Clyde Puilingi, Yukari Maeno, Aodhan Beattie, Andrew Allen, Mari Yotsu-Yamashita, Todd Michael, and Bradley Moore*, Domoic acid biosynthesis and genome expansion in Nitzschia navis-varingica, mBio, 2025, 0:e02079-25.  https://doi.org/10.1128/mbio.02079-25

Mari Yotsu-Yamashita*, Yuta Kudo, Kyoka Sato, Osamu Chiba, Yuko Cho, Ryuichi Watanabe, Toshiyuki Suzuki, and Keiichi Konoki, Chemical properties and biological activities of highly purified three major tetrodotoxin analogues, Proc. Jpn. Acad. Ser. B. 2025, 101, 519–533. https://doi.org/10.2183/pjab.101.033

Tadachika Miyasaka, Yuta Kudo, Mari Yostu-Yamashita, Masaatsu Adachi, Toshio Nishikawa*, Synthetic Studies Toward 4,9-Anhydro-10-hemiketal-5-deoxy-tetrodotoxin, A Proposed Biosynthetic Precursor of Tetrodotoxin, SYNLETT, 2025, 36(12): 1735-1738.

https://www.thieme-connect.de/products/ejournals/pdf/10.1055/s-0043-1773544.pdf

DOI: 10.1055/s-0043-1773544

Y. Kudo*, K. Konoki and M. Yotsu-Yamashita, Identification of γ-Butyrolactone Signalling Molecules in Diverse Actinomycetes Using Resin-Assisted Isolation and Chemoenzymatic Synthesis, RSC Chem. Biol.,2025, 6, 630–641. https://doi.org/10.1039/D5CB00007F (open access).

Ryosuke Hirozumi, Yuta Kudo, Yuko Cho, Keiichi Konoki, Mari Yotsu-Yamashita*, Total Synthesis and Structural Revision of (±)-Mauritamide B, J. Nat. Prod., 2025, 88, 3, 806–814. https://doi.org/10.1021/acs.jnatprod.5c00019 (open access).

Mari Yotsu-Yamashita*, Kairi Umeda, Arihiro Iwasaki, Kiyotake Suenaga, Toxicity of the marine glycosidic macrolides, polycavernoside E and akunolides, from Okinawan cyanobacterium Okeania sp. in mice, Toxicon 2024, 108122-108122, (open access), https://doi.org/10.1016/j.toxicon.2024.108122.

Yuko Cho*, Shizu Hidema, Takuo Omura, Shigeki Tsuchiya, Keiichi Konoki, Yasukatsu Oshima, Mari Yotsu-Yamashita, Intracellular abundance, localization, and enzymatic activity of a saxitoxin biosynthesis enzyme, SxtG, in two sister subclones of the dinoflagellate Alexandrium catenella with extremely different levels of paralytic shellfish toxins, Harmful Algae 2024, 139, 102723-102723 (open access), https://doi.org/10.1016/j.hal.2024.102723.

Ryosuke Hirozumi, Mayu Hakamada, Takashi Minowa, Yuko Cho, Yuta Kudo, Keiichi Konoki, Yasukatsu Oshima, Kazuo Nagasawa, Mari Yotsu-Yamashita*, Synthesis of Saxitoxin Biosynthetic Intermediates: Reveal the Mechanism for Formation of its Tricyclic Skeleton in Biosynthesis, Chemistry - An Asian Journal,2024, e202400834 (open access), https://doi.org/10.1002/asia.202400834.

Masato Terauchi,†, Yuki Komazaki,†, Atsushi Yoshino, Yuko Cho, Yuta Kudo, Mari Yotsu-Yamashita, Keiichi Konoki∗,†These authors contributed equally to this work. Assay for okadaic acid O-acyl transferase using HPLC-FLD, Bioscience, Biotechnology, and Biochemistry, 2024, 88, 99-1006. https://doi.org/10.1093/bbb/zbae085

Tatsunari Shingai*, Yoshiko Chiba, Mitsue Kondo, Mari Yotsu-Yamashita, Temporal variation in the concentrations and profiles of paralytic shellfish toxins and tetrodotoxin in scallop (Mizuhopecten yessoensis) and bloody clam (Anadara broughtonii) collected from the coast of Miyagi Prefecture, Japan, Toxicon, 2024,107710. https://doi.org/10.1016/j.toxicon.2024.107710.

M. Hakamada‡, C. Tokairin‡, H. Ishizuka‡, K. Adachi, T. Osawa, S. Aonuma, R. Hirozumi, S. Tsuchiya, Y. Cho, Y. Kudo, K. Konoki, Y. Oshima, K. Nagasawa*, M. Yotsu-Yamashita*, Synthesis and Identification of decarbamoylosySaxitoxins in Toxic Microalgae and their Reaction with the Oxygenase, SxtT, Reveal Saxitoxin Biosynthesis, Chem. Eur. J. e202304238 (2024).  http://dx.doi.org/10.1002/chem.202304238

‡These authors contributed equally to this work. (Open access).

Hayate Ishizuka, Ayato Nureki, Kanna Adachi, Yuka Takayanagi, Minami Odagi, Mari Yotsu-Yamashita, and Kazuo Nagasawa*, Approaches to Construction of the Medium-Sized Ring Structure in Zetekitoxin AB by Ring-Closing Metathesis, J. Org. Chem. 2023, 88, 14, 10223–10231. https://pubs.acs.org/doi/10.1021/acs.joc.3c00580

Shota Itoda, Ryuichi Watanabe, Mayu Ozawa, Hajime Uchida, Ryoji Matsushima, Hiroshi Oikawa, Hideto Fukushima, Masahiro Matsumiya, Mari Yotsu-Yamashita and Toshiyuki Suzuki＊, Chemical analysis of tetrodotoxins in foods made using pufferfish ovaries pickled in salt and rice-bran, Nippon Suisan Gakkaishi,2023, 89 (3), 244-249. DOI: 10.2331/suisan.22-00051

Ayato Nureki, Kanna Adachi, Hayate Ishizuka, Kako Maeno, Yayoi Orihara, Minami Odagi, Mari Yotsu-Yamashita, Kazuo Nagasawa*, Stereoselective Construction of Tertiary Alcohol at C11 of Zetekitoxin AB, Asian J. Org. Chem., 2023, e202300205, https://doi.org/10.1002/ajoc.202300205

Keita Yamaki, Kyoka Sato, Yuta Kudo, Yuko Cho, Keiichi Konoki, Tomohiro Takatani, Osamu Arakawa, Kentaro Kawatsu*, and Mari Yotsu-Yamashita*, The quite low cross-reactivity of Kawatsu’s anti-tetrodotoxin monoclonal antibody to 5,6,11-trideoxytetrodotoxin, 11-nortetrodotoxin-6(S)-ol, and 11-oxotetrodotoxin, the major tetrodotoxin analogues in pufferfish, Toxicon, 2023, 226, 107081. https://doi.org/10.1016/j.toxicon.2023.107081

Yuko Cho*, Shigeki Tsuchiya, Takuo Omura, Kazuhiko Koike, Keiichi Konoki, Yasukatsu Oshima, Mari Yotsu-Yamashita. Metabolic inhibitor induces dynamic changes in saxitoxin biosynthesis and metabolism in the dinoflagellate Alexandrium pacificum (Group IV) under in vivo labeling condition, Harmful Algae, 2023, 122, 102372. https://doi.org/10.1016/j.hal.2022.102372

CT Hanifin, Y Kudo, M Yotsu-Yamashita, Chemical Ecology of the North American Newt Genera Taricha and Notophthalmus, 102-121.

Springer Nature Switzerland AG 2022, A. D. Kinghorn, H. Falk, S. Gibbons, Y. Asakawa, J-K. Liu, V. M. Kirsch (eds.),  Progress in the Chemistry of Organic Natural Products 118,2 https://doi.org/10.1007/978-3-030-92030-2_3

Osamu Chiba1, Noriko Shimada1, Shutaro Yoshio, Yuta Kudo, Yuko Cho, Mari Yotsu-Yamashita, Keiichi Konoki*, State-Dependent Inhibition of Voltage-Gated Sodium Channels in Neuroblastoma Neuro-2A Cells by Arachidonic Acid from Halichondria okadai, Chemical Research in Toxicology, 2022, 35, 11, 1950-1961.1These authors contributed equally to this work. https://pubs.acs.org/doi/10.1021/acs.chemrestox.2c00062

Ryoma Minami, Kaori Taniguchi, Hironobu Matsuo, Kazunari Tsujimura, Ryoma Miura, Yusuke Shibahara, Kentaroi Kawatsu, Mari Yotsu-Yamashita, Tomohiro Takatani, Osamu Arakawa*, Screening method for tetrodotoxin using immunochromatographic test kit, Nippon Suisan Gakkaishi, 2022, 88(6) 515-522. DOI: 10.2331/suisan.22-00031

Yuji Yaegashi, Yuta Kudo, Nozomi Ueyama, Ken-ichi Onodera, Yuko Cho, Keiichi Konoki, Mari Yotsu-Yamashita*, Isolation and biological activity of 9-epiTetrodotoxin, and isolation of Tb-242B, possible biosynthetic shunt products of tetrodotoxin from pufferfish, J. Nat. Prod. 2022, 85, 2199–2206. https://pubs.acs.org/doi/10.1021/acs.jnatprod.2c00588.

Gorapava, C.; Nih, S.; Maeno, Y.; Pin, C.; Teen, P.; Yotsu-Yamashita, M.; Terada, R.; Kotaki, Y.* First record of the diatom Nitzschia Navis-varingica ( Bacillariophyceae ) producing Amnesic Shellfish Poisoning-Toxins from Papua New Guinea. Toxicon 2022, 216, 65–72. https://doi.org/10.1016/j.toxicon.2022.06.016

Atsuo Nakazaki,* Shunsuke Mouri, Yoshiki Nakane, Yuki Ishikawa, Mari Yotsu-Yamashita, and Toshio Nishikawa, The synthesis of simplified analogues of crambescin b carboxylic acid and their inhibitory activity of voltage-gated sodium channels: new aspects of structure–activity relationships, Heterocycles 2022, 105, 343–351. DOI: 10.3987/COM-21-S(R)7

Yuta Kudo*,  Keiichi Konoki,  Mari Yotsu-Yamashita*, Mass spectrometry–guided discovery of new analogues of bicyclic phosphotriester salinipostin and evaluation of their monoacylglycerol lipase inhibitory activity, Bioscience, Biotechnology, and Biochemistry, 2022, 86, 1333–1342. https://doi.org/10.1093/bbb/zbac131

Watanabe, R.; Takayanagi, Y.; Chiba, O.; Itoda, S.; Ishizuka, H.; Odagi, M.; Ozawa, M.; Uchida, H.; Matsushima, R.; Konoki, K.; Yotsu-Yamashita*, M.; Nagasawa*, K.; Suzuki*, T. Nontoxic Enantiomeric Reference Materials for Saxitoxins. 2022. Analytical Chemistry, 94, 32, 11144–11150. https://doi.org/10.1021/acs.analchem.2c00836

Michiru Akamatsu1, Ryosuke Hirozumi1, Yuko Cho, Yuta Kudo, Keiichi Konoki, Yasukatsu Oshima, Mari Yotsu-Yamashita*, First Identification of 12β-Deoxygonyautoxin 5 (12α-Gonyautoxinol 5) in the Cyanobacterium Dolichospermum circinale (TA04) and 12β-Deoxysaxitoxin (12α-Saxitoxinol) in D. circinale (TA04) and the Dinoflagellate Alexandrium pacificum (Group IV) (120518KureAC), Marine Drugs, 2022, 20(3) 166. https://doi.org/10.3390/md20030166. 1These authors contributed equally to this work. 

Taylor S. Steele1, John K. Brunson1, Yukari Maeno, Ryuta Terada, Andrew E. Allen, Mari Yotsu-Yamashita, Jonathan, R. Chekan*, Bradley S. Moore*, Domoic acid biosynthesis in the red alga Chondria armatasuggests a complex evolutionary history for toxin production, Proc. Natl. Acad. Sci. U.S.A., 2022, 119(6) e2117407119. 

https://doi.org/10.1073/pnas.2117407119. 1These authors contributed equally to this work.

Dietrich Mebs,*, Julio V. Schneider, Oskar Schr¨oder, Mari Yotsu-Yamashita, John R. Harley, Linda Mogk, Gunther K¨ohler, A study on the genetic population structure and the tetrodotoxin content of rough-skinned newts, Taricha granulosa (Salamandridae), from their northern range of distribution, Toxicon 206 (2022) 38–41. https://doi.org/10.1016/j.toxicon.2021.12.010

Yukari Maeno, Yuichi Kotaki, Ryuta Terada, Masafumi Hidaka, Yuko Cho, Keiichi Konoki, and Mari Yotsu-Yamashita*,　Preparation of domoic acid analogues using a bioconversion system, and their toxicity in mice, online published, Organic & Biomolecular Chemistry, 2021, 19, 7894-7902. 

https://doi.org/10.1039/D1OB01378E

Dietrich Mebs* and Mari Yotsu-Yamashita, Acquiring toxicity of a newt, Cynops orientalis, Toxicon, 2021,198, 32–35. 

https://doi.org/10.1016/j.toxicon.2021.04.025

Yuta Kudo, Charles T. Hanifin, and Mari Yotsu-Yamashita*, Identification of Tricyclic Guanidino Compounds from the Tetrodotoxin-Bearing Newt Taricha granulosa, Org. Lett., 2021, 23, 3513-3517.

https://doi.org/10.1021/acs.orglett.1c00916  

Two new skeletal analogues of saxitoxin found in the scallop, Patinopecten yessoensis, as possible metabolites of paralytic shellfish toxins, Satoshi Numano, Yuta Kudo, Yuko Cho, Keiichi Konoki, Yoshimasa Kaga, Kazuo Nagasawa, and Mari Yotsu-Yamashita*, Chemosphere, 2021, 278, 130224.

https://doi.org/10.1016/j.chemosphere.2021.130224

Keisuke Nishikawa,* Takayuki Noguchi, Seiho Kikuchi, Takahiro Maruyama, Yusuke Araki, Mari Yotsu-Yamashita, and Yoshiki Morimoto*, Tetrodotoxin Framework Construction from Linear Substrates Utilizing a Hg(OTf)2‐Catalyzed Cycloisomerization Reaction: Synthesis of the Unnatural Analogue 11-nor-6,7,8-Trideoxytetrodotoxin, Organic Letters, 2021, 23, 1703-1708.

https://dx.doi.org/10.1021/acs.orglett.1c00125

Mari Yotsu-Yamashita, Gunther Köhler, Dietrich Mebs,* Polypedates Leucomystax (White-lipped Tree Frog) Toxicity. Herpetological Review, 51(4), 2020, 822-823.

Yuko Cho*, Shizu Hidema, Takuo Omura, Kazuhiko Koike, Kanae Koike, Hiroshi Oikawa, Keiichi Konoki, Yasukatsu Oshima, and Mari Yotsu-Yamashita, SxtA localizes to chloroplasts and changes to its 3’UTR may reduce toxin biosynthesis in non-toxic Alexandrium catenella  (Group I), Harmful Algae, 101, 101972, 2021. Invited Feature Article.  

http://doi.org/10.1016/j.hal.2020.101972

Yuta Kudo, Charles Hanifin, Yuichi Kotaki, Mari Yotsu-Yamashita*, Structures of N-hydroxy-type tetrodotoxin analogues and bicyclic guanidinium compounds found in toxic newts, Journal of Natural Products, 2020, 83, 9, 2706-2717. ACS Editor’s Choice.  (Open access) 

https://pubs.acs.org/doi/abs/10.1021/acs.jnatprod.0c00623

Dietrich Mebs*, Mari Yotsu-Yamashita, Katharina Hartmann, Christine Elbert, Richard Zehner, Stefan W. Toennes

Revisited - Failure of tetrodotoxin to protect red-spotted newts, Notophthalmus viridescens, from endoparasites, Toxicon, 2020, 178, 77–81.

https://doi.org/10.1016/j.toxicon.2020.02.026

Kanna Adachi,‡ Tomoshi Yamada,‡ Hayate Ishizuka, Mana Oki, Shunsuke Tsunogae, Noriko Shimada, Osamu Chiba, Tatsuya Orihara, Masafumi Hidaka, Takatsugu Hirokawa, Minami Odagi, Keiichi Konoki,* Mari Yotsu-Yamashita,* Kazuo Nagasawa* (‡ contributed equally to this work), Synthesis of C12‐keto saxitoxin derivatives with unusual inhibitory activity against voltage‐gated sodium channels, Chem. Eur. J., 2020, 26, 2025-2033. 

https://doi.org/10.1002/chem.201904184

Ryuichi Watanabe, Masato Tanioka, Hajime Uchida, Ryoji Matsushima, Hiroshi Oikawa,Masahiro Matsumiya, Mari Yotsu-Yamashita, and Toshiyuki Suzuki*, Quantitation of Tetrodotoxin and Its Analogues with a Combination of Liquid Chromatography−Tandem Mass Spectrometry and Quantitative 1H NMR Spectroscopy, J. Agric. Food Chem. 2019, 67, 46, 12911-12917.

http://pubs.acs.org/doi/abs/10.1021/acs.jafc.9b06380

Satoshi Numano, Yuta Kudo, Yuko Cho, Keiichi Konoki and Mari Yotsu-Yamashita,* Temporal Variation of the Profile and Concentrations of Paralytic Shellfish Toxins and Tetrodotoxin in the Scallop, Patinopecten yessoensis, Cultured in a Bay of East Japan, Mar. Drugs 2019,17(12), 653; https://doi.org/10.3390/md17120653 (open access)

Keiichi Konoki*, Daniel G. Baden, Todd Scheuer and W liam A. Catterall, Molecular Determinants of Brevetoxin Binding to Voltage-Gated Sodium Channels, Toxins 2019, 11(9), 513. http://doi.org/10.3390/toxins11090513 (open access)

Takashi Minowa, Yuko Cho, Yasukatsu Oshima, Keiichi Konoki and Mari Yotsu-Yamashita*, Identification of a Novel Saxitoxin Analogue, 12β-Deoxygonyautoxin 3, in the Cyanobacterium, Anabaena circinalis (TA04), Toxins 2019, 11(9), 539. http://doi.org/10.3390/toxins11090539 (open access)

Yukari Maeno, Ryuta Terada, Yuichi Kotaki, Yuko Cho, Keiichi Konoki, and Mari Yotsu-Yamashita*, Possible biosynthetic products and metabolites of kainic acid from the red alga, Digenea simplex, and their biological activity, Journal of Natural Products, 2019, 82, 1627-1633. https://pubs.acs.org/doi/10.1021/acs.jnatprod.9b00128

Yuta Kudo and Mari Yotsu-Yamashita*, Isolation and biological activity of 8-epitetrodotoxin and the structure of a possible biosynthetic shunt product of tetrodotoxin, Cep-226A, from the newt, Cynops ensicauda popei, Journal of Natural Products, 2019, 82, 1656-1663. https://pubs.acs.org/doi/10.1021/acs.jnatprod.9b00178

Yuko Cho*, Shigeki Tsuchiya, Takuo Omura, Kazuhiko Koike, Hiroshi Oikawa, Keiichi Konoki, Yasukatsu Oshima, Mari Yotsu-Yamashita, Metabolomic study of saxitoxin analogues and biosynthetic intermediates in dinoflagellates using 15N-labelled sodium nitrate as a nitrogen source, Scientific Reports, 2019, 9: 3460. https://www.nature.com/articles/s41598-019-39708-y

Masaatsu Adachi*, Tadachika Miyasaka, Yuta Kudo, Keita Sugimoto, Mari Yotsu-Yamashita, and Toshio Nishikawa*, Total Syntheses and Determination of Absolute Configurations of Cep-212 and Cep-210, Predicted Biosynthetic Intermediates of Tetrodotoxin Isolated from Toxic Newt, Organic Letters, 2019, 21, 780-784. https://pubs.acs.org/doi/full/10.1021/acs.orglett.8b04043

Dietrich Mebs*, Mari Yotsu-Yamashita, Stefan W. Toennes, Tetrodotoxin content of Rough-skinned Newts, Taricha granulosa (Salamandridae), from their northern distribution range, British Columbia, Canada, and Southeast-Alaska, USA, Salamandra  55(2), 82-88, 2019. ISSN 0036-3375 http://www.salamandra-journal.com/index.php/home/contents/2019-vol-55/ - Volume55-2

Andrew J. Jang*, Ji-Hyeok Lee, Mari Yotsu-Yamashita, Joodong Park, Steve Kye, Raymond L. Benza, Michael J. Passineau, You-Jin Jeon & Toru Nyunoya A Novel Compound, “FA-1” Isolated from Prunus mume, Protects Human Bronchial Epithelial Cells and Keratinocytes from Cigarette Smoke Extract-Induced Damage, Scientific Reports, 8, 11504, 2018.

https://doi.org/10.1038/s41598-018-29701-2

Dietrich Mebs*, Mari Yotsu-Yamashita, Werner Pogoda, Joseph Vargas Alvarez, Raffael Ernst, Gunther Köhler, Stefan W. Toennes, Lack of alkaloids and tetrodotoxin in the neotropical frogs Allobates spp. (Aromobatidae) and Silverstoneia flotator (Dendrobatidae)

Toxicon 152, 103–105, 2018.

https://doi.org/10.1016/j.toxicon.2018.07.027

Mari Yotsu-Yamashita*, Yuuma Nagaoka, Koji Muramoto, Yuko Cho and Keiichi Konoki, Pufferfish Saxitoxin and Tetrodotoxin Binding Protein (PSTBP) Analogues in the Blood Plasma of the Pufferfish Arothron nigropunctatus, A. hispidus, A. manilensis, and Chelonodon patoca, Mar. Drugs 2018, 16(7), 224.

https://doi.org/10.3390/md16070224

Sou Kikuchi1, Kayo Okada1, Yuko Cho, Shinichiro Yoshida, Eunsang Kwon, Mari Yotsu-Yamashita, Keiichi Konoki*, Isolation and structure determination of lysiformine from bacteria associated with marine sponge Halichondria okadai, Tetrahedron 2018, 74, 3742-3747. (1 These authors contributed equally to this work.)

https://dx.doi.org/10.1016/j.tet.2018.05.049

Dietrich Mebs∗, Max Lorentz⁠, Mari Yotsu-Yamashita⁠, Daniela C. Rößler⁠, Raffael Ernst⁠, Stefan Lötters⁠, Geographic range expansion of tetrodotoxin in amphibians – First record in Atelopus hoogmoedi from the Guiana Shield, Toxicon, 2018, 150, 175-179.

https://dx.doi.org/10.1016/j.toxicon.2018.05011

Nozomi Ueyama, Keita Sugimoto, Yuta Kudo, Ken-ichi Onodera, Yuko Cho, Keiichi Konoki, Toshio Nishikawa, Mari Yotsu-Yamashita*, Spiro Bicyclic Guanidino Compounds from Pufferfish, Possible Biosynthetic Intermediates of Tetrodotoxin in Marine Environments, Chemistry, a European Journal, 2018, 24, 7250-7258. 

http://dx.doi.org/10.1002/chem.201801006.

Yukari Maeno, Yuichi Kotaki, Ryuta Terada, Yuko Cho, Keiichi Konoki, Mari Yotsu-Yamashita*, Six domoic acid related compounds from the red alga, Chondria armata, and domoic acid biosynthesis by the diatom, Pseudo-nitzschia multiseries, Scientific Reports | (2018) 8:356 DOI:10.1038/s41598-017-18651-w 

Open access: www.nature.com/articles/s41598-017-18651-w

Dietrich Mebs* and Mari Yotsu-Yamashita, Taricha granulosa (Rough-Skinned Newt) Predation, Herpetological Review, 2017, 48(4), 828-829.

Kotaro Iwasaki, Satori Sasaki, Yusuke Kasai, Yuki Kawashima, Shohei Sasaki, Takanori Ito, Mari Yotsu-Yamashita, and Makoto Sasaki,* Total Synthesis of Polycavernosides A and B, Two Lethal Toxins from Red Alga. The Journal of Organic Chemistry, 82, 13204-13219 (2017). DOI:10.1021/acs.joc.7b02293 

Tadaaki Tsukamoto, Yukie Chiba, Minoru Wakamori, Tomoshi Yamada, Shunsuke Tsunogae, Yuko Cho, Ryo Sakakibara, Takuya Imazu, Shouta Tokoro, Yoshiki Satake, Masaatsu Adachi, Toshio Nishikawa, Mari Yotsu-Yamashita, and Keiichi Konoki,* Differential binding of tetrodotoxin and its derivatives to voltage-sensitive sodium channel subtypes (Nav1.1 to Nav1.7), British Journal of Pharmacology, 2017, 174, 3811-3892. http://onlinelibrary.wiley.com/doi/10.1111/bph.13985/full

Yuta Kudo, Chikafumi Chiba, Keiichi Konoki, Yuko Cho and Mari Yotsu-Yamashita*, Dietary administration of tetrodotoxin and its putative biosynthetic intermediates to the captive-reared non-toxic Japanese fire-bellied newt, Cynops pyrrhogaster. Toxicon, 2017, 134, 78-82. https://doi.org/10.1016/j.toxicon.2017.07.016

Yotsu-Yamashita, M., Toennes, S.W., Mebs, D.*, Tetrodotoxin in Asian newts (Salamandridae), Toxicon,2017, 134, 14-17.

doi: 10.1016/j.toxicon.2017.05.014. 

Shigeki Tsuchiya, Yuko Cho, Renpei Yoshioka, Keiichi Konoki, Kazuo Nagasawa, Yasukatsu Oshima, and Mari Yotsu-Yamashita*, Synthesis and identification of key biosynthetic intermediates for the formation of the tricyclic skeleton of saxitoxin, Angew. Chem. Int. Ed., 2017, 56, 5327-5331. 

http://onlinelibrary.wiley.com/doi/10.1002/anie.201612461/full

See also: http://www.chemistryviews.org/details/ezine/10513592/Biosynthesis_of_Saxitoxin.html

Tadaaki Tsukamoto, Yukie Chiba, Atsuo Nakazaki, Yuki Ishikawa, Yoshiki Nakane, Yuko Cho, Mari Yotsu-Yamashita, Toshio Nishikawa, Minoru Wakamori, and Keiichi Konoki,* Inhibition of veratridine-induced delayed inactivation of the voltage-sensitive sodium channel by synthetic analogs of crambescin B, Bioorganic & Medicinal Chemistry Letters, 2017, 27, 1247-1251.http://dx.doi.org/10.1016/j.bmcl.2017.01.054

Clyde Gorapava Puilingi, Yuta Kudo, Yuko Cho, Keiichi Konoki, and Mari Yotsu-Yamashita*, A new sarasinoside congener, sarasinoside M2, from a marine sponge collected in the Solomon Islands, Bioscience, Biotechnology, and Biochemistry, 2017, 81, 222-225.  http://dx.doi.org/10.1080/09168451.2016.1246172

Mebs, D.,* M. Yotsu-Yamashita, J. Ream, B. K. Zajac & R. Zehner: Tetrodotoxin concentrations in rough-skinned newts, Taricha granulosa, from populations of their northern distribution range. Sarlamandra, 52(3), 255-206 (2016).

http://www.salamandra-journal.com/index.php?option=com_docman&Itemid=80

Yuko Cho*, Shigeki Tsuchiya, Renpei Yoshioka, Takuo Omura, Keiichi Konoki, Yasukatsu Oshima, Mari Yotsu-Yamashita, Column switching combined with hydrophilic interaction chromatography-tandem mass spectrometry for the analysis of saxitoxin analogues, and their biosynthetic intermediates in dinoflagellates. Journal of Chromatography A, 2016, 1474, 109-120. http://dx.doi.org/10.1016/j.chroma.2016.10.065

Yu Onodera, Kazuaki Hirota, Yuto Suga, Keiichi Konoki, Mari Yotsu-Yamashita, Makoto Sasaki, and Haruhiko Fuwa*, Diastereoselective Ring-Closing Metathesis as a Means to Construct Medium-Sized Cyclic Ethers: Application to the Synthesis of a Photoactivatable Gambierol Derivative, J. Org. Chem., 2016, 81 (18), 8234_8252, 2016. DOI: 10.1021/acs.joc.6b01302

Chao Wang,  Mana Oki, Toru Nishikawa, Daisuke Harada, Mari Yotsu-Yamashita and Kazuo Nagasawa*, Total Synthesis of 11-Saxitoxinethanoic Acid and Evaluation of its Inhibitory Activity on Voltage-gated Sodium Channels, Angew. Chem. Int. Ed., 55 (38), 11600_11603, 2016. DOI: 10.1002/anie.201604155

Naoyuki Umemoto*, Masaru Nakayasu, Kiyoshi Ohyama, Mari Yotsu-Yamashita, Masaharu Mizutani, Hikaru Seki, Kazuki Saito, and Toshiya Muranaka, Two Cytochrome P450 Monooxygenases Catalyze Early Hydroxylation Steps in the Potato Steroid Glycoalkaloid Biosynthetic Pathway. Plant Physiol. 171, 2458-2467, 2016.; doi:10.1104/pp.16.00137

Atsuo Nakazaki, Yoshiki Nakane, Yuki Ishikawa, Mari Yotsu-Yamashita and Toshio Nishikawa*, Asymmetric synthesis of crambescin A_C carboxylic acids and their inhibitory activity on voltage-gated sodium channels, Org. Biomol. Chem., 14, 5304-5309, 2016, DOI: 10.1039/c6ob00914j

Shogo Saruhashi, Keiichi Konoki, and Mari Yotsu-Yamashita*, The voltage-gated sodium ion channel inhibitory activities of a new tetrodotoxin analogue, 4,4a-anhydrotetrodotoxin, and three other analogues evaluated by colorimetric cell-based assay, Toxicon, 119, 72-76, 2016. doi:10.1016/j.toxicon.2016.05.012

Sachie Furumochi, Tatsuya Onoda, Yuko Cho, Haruhiko Fuwa, Makoto Sasaki, Mari Yotsu-Yamashita, and Keiichi Konoki*, Effect of carbon chain length in acyl coenzyme A on the efficiency of enzymatic transformation of okadaic acid to 7-O-acyl okadaic acid, Bioorg. Med. Chem. Lett., 26, 2992-2996, 2116. doi:10.1016/j.bmcl.2016.05.027

Yuta Kudo, Takeshi Yasumoto, Dietrich Mebs, Yuko Cho, Keiichi Konoki, and Mari Yotsu-Yamashita*, Cyclic Guanidine Compounds From Newts Support the Hypothesis that Tetrodotoxin is Derived From Monoterpene. Angew. Chem. Int. Ed., 55, 8728-8731, 2016. DOI:10.1002/anie.201602971, Angew. Chem. 128 (30), 8870_8873. DOI: 10.1002/ange.201602971.

Davide Romani, Shigeki Tsuchiya, Mari Yotsu-Yamashita, Silvia A. Brand_n*, Spectroscopic and structural investigation on intermediates species structurally associated to the tricyclic bisguanidine compound and to the toxic agent, saxitoxin, Journal of Molecular Structure, 2016, 1119, 25-38.doi:10.1016/j.molstruc.2016.04.039

http://www.sciencedirect.com/science/article/pii/S0022286016303581

.

Dietrich Mebs*, Mari Yotsu-Yamashita and Osamu Arakawa, The praying mantis (Mantodea) as predator of the poisonous red-spotted newt

Notophthalmus viridescens (Amphibia: Urodela: Salamandridae), Chemoecology, 2016, http://link.springer.com/article/10.1007/s00049-016-0211-3

Shigeki Tsuchiya, Yuko Cho, Keiichi Konoki, Kazuo Nagasawa, Yasukatsu Oshima and Mari Yotsu-Yamashita,* Biosynthetic route towards saxitoxin and shunt pathway. Scientific Reports, 2016, 6:20340 | DOI: 10.1038/srep20340. http://www.nature.com/articles/srep20340 (Open access)

Keiichi Konoki*, Kayo Okada, Mami Kohama, Hiroki Matsuura, Kaori Saito, Yuko Cho, Goh Nishitani, Tomofumi Miyamoto, Seketsu Fukuzawa, Kazuo Tachibana, Mari Yotsu-Yamashita, Identification of okadaic acid binding protein 2 in reconstituted sponge cell clusters from Halichondria okadai and its contribution to the detoxification of okadaic acid. Toxicon, 2015, 108, 38-45. doi:10.1016/j.toxicon.2015.09.026

Yuko Cho*, Shigeki Tsuchiya, Renpei Yoshioka, Takuo Omura, Keiichi Konoki, Yasukatsu Oshima and Mari Yotsu-Yamashita, The presence of 12-deoxydecarbamoylsaxitoxin in the Japanese toxic dinoflagellate Alexandrium determined by simultaneous analysis for paralytic shellfish toxins using HILIC-LC-MS/MS, Harmful Algae, Harmful Algae, 2015, 49, 58-67. doi:10.1016/j.hal.2015.09.003

Clyde Gorapava Puilingi, Yuta Kudo, Yuko Cho, Keiichi Konoki, Mari Yotsu-Yamashita*, Tetrodotoxin and its analogues in the pufferfish Arothron hispidus and A. nigropunctatus from the Solomon Islands: A comparison of their toxin profiles with the same species from Okinawa, Japan, Toxins, 2015, 7, 3436-3454. 

http://www.mdpi.com/2072-6651/7/9/3436/pdf (open access)

Ehara H, Makino M, Kodama K, Konoki K, Ito T, Sekine S, Fukuzawa S*, Yokoyama S*, Tachibana K*, Crystal Structure of Okadaic Acid Binding Protein 2.1: A Sponge Protein Implicated in Cytotoxin Accumulation. ChemBioChem. 2015, 16(10):1435-9. 

doi: 10.1002/cbic.201500141

Yuta Kudo, Chikafumi Chiba, Yuko Cho, Keiichi Konoki, Mari Yotsu-Yamashita*, Confirmation of the absence of tetrodotoxin and its analogues in the juveniles of the Japanese fire-bellied newt, Cynops pyrrhogaster, captive-reared from eggs in the laboratory using HILIC-LC-MS, Toxicon, 2015, 101, 101-105.

doi:10.1016/j.toxicon.2015.05.008

Shigeki Tsuchiya, Yuko Cho, Keiichi Konoki, Kazuo Nagasawa, Yasukatsu Oshima, and Mari Yotsu-Yamashita*, Synthesis of a tricyclic bisguanidine compound structurally related to saxitoxin and its identification in paralytic shellfish toxins-producing microorganisms, Chem. Eur. J. 2015, 21, 7835-7840.

DOI: 10.1002/chem.201500064

see also: http://www.chemistryviews.org/details/ezine/7892661/A_Pathway_to_Saxitoxin.html.

Noriyoshi Teramoto* and Mari Yotsu-Yamashita, Selective Blocking Effects of 4,9-Anhydrotetrodotoxin, Purified from a Crude Mixture of Tetrodotoxin Analogues, on NaV1.6, Channels and Its Chemical Aspects, Marine Drugs 13, 984-995, 2015 (Review) (open access: http://www.mdpi.com/1660-3397/13/2/984.) 

DOI:10.3390/md13020984

(Review).

Keiichi Konoki,*, Yuto Suga, Haruhiko Fuwa, Mari Yotsu-Yamashita, and Makoto Sasaki,* Evaluation of gambierol and its analogs for their inhibition of human Kv1.2 and cytotoxicity, Bioorg. Med. Chem. Lett., 2014, 25, 514-518.

DOI:10.1016/j.bmcl.2014.12.022

Nicolaou, K. C.*, Heretsch, P., Nakamura, T., Rudo A., Murata, M, and Konoki, K. Synthesis and Biological Evaluation of QRSTUVWXYZA' Domains of Maitotoxin. J Am Chem Soc., 2014, 136, 16444_16451.

Kunitake, M., Oshima, T., Konoki, K., Ebine, M., Torikai, K., Murata, M., and Oishi, T.* Synthesis and biological activity of the C'D'E'F' ring system of maitotoxin. J Org Chem. 2014, 79, 4948-4962. doi: 10.1021/jo5005235.

Onoue, H., Baba, T., Konoki, K., Torikai, K., Ebine, M., and Oishi, T.* Synthesis and Biological Activity of the QRS Ring System of Maitotoxin. Chem. Lett. 2014, 43, 1904-1906.

Yuta Kudo, Yoko Yamashita, Dietrich Mebs, Yuko Cho, Keiichi Konoki, Takeshi Yasumoto, and Mari Yotsu-Yamashita*, C5_C10 Directly bonded tetrodotoxin analogues: Possible biosynthetic precursors of tetrodotoxin from newts. Angew. Chem. Int. Ed. 2014, 53, 14546-14549.

.

Yoshiki Satake, Masaatsu Adachi, Shouta Tokoro, Mari Yotsu-Yamashita, Minoru Isobe, and Toshio Nishikawa*, Synthesis of 5- and 8-Deoxytetrodotoxin, Chem. Asian J. 2014, 9, 1922 _ 1932.

Yuma Kudo, Akihiro Abe, Kumiko Ito, Yuko Cho, Mari Yotsu-Yamashita, and Keiichi Konoki*, Expression of recombinant alpha and beta tubulins from the yew Taxus cuspidata and analysis of the microtubule assembly in the presence of taxol, Bioscience, Biotechnology, and Biochemistry, accepted (9th June, 2014).

Shigeki Tsuchiya, Yuko Cho, Keiichi Konoki, Kazuo Nagasawa, Yasukatsu Oshima and Mari Yotsu-Yamashita*, Synthesis and identification of proposed biosynthetic intermediates of saxitoxin in the cyanobacterium Anabaena circinalis (TA04) and the dinoflagellate Alexandrium tamarense (Axat-2), Org. Biomol. Chem., 12, 3016-3020, 2014.

Yuta Kudo, Julian Finn, Kohei Fukushima, Satsuki Sakugawa, Yuko Cho, Keiichi Konoki, and Mari Yotsu-Yamashita*, Isolation of 6-deoxytetrodotoxin from the pufferfish, takifugu pardalis, and a comparison of the effects of the C-6 and C-11 hydroxy groups of tetrodotoxin on its activity, J. Nat. Prod., 77, 1000-1004, 2014.

Mori, Tadashi; HIDAKA, Masafumi; Ikuji, Hiroko; Yoshizawa, Ibuki; TOYOHARA, Haruhiko; Okuda, Toru; Uchida, Chiyoko; Asano, Tomoichiro; Yotsu-YAMASHITA, Mari; UCHIDA, Takafumi*, A High-Throughput Screen for Inhibitors of the Prolyl Isomerase, Pin1, Identifies a Seaweed Polyphenol that Reduces Adipose Cell Differentiation, Bioscience, Biotechnology, and Biochemistry, 78, 832-838, 2014,http://dx.doi.org/10.1080/09168451.2014.905189. 

Yuko Cho*, Motoo Ogawa, Mari Yotsu-Yamashita, and Yasukatsu Oshima, Effect of 5-fluoro-2f-deoxyuridine on toxin production and cell cycle regulation in marine dinoflagellate, Alexandrium tamarense, Harmful Algae, 32, 64-72, 2014.

Atsuo Nakazaki, Yuki Ishikawa, Yusuke Sawayama, Mari Yotsu-Yamashita, Toshio Nishikawa*, Synthesis of crambescin B carboxylic acid, a potent inhibitor of voltage-gated sodium channels, Org. Biomol. Chem., 12, 53-56, 2014.

Yoshihisa Tanaka, Masayuki Satake,* Mari Yotsu-Yamashita, and Yasukatsu Oshima, Gymnocin-A carboxylic acid and gymnocin-a2,

cytotoxic polyethers from the red tide dinoflagellate Karenia mikimotoi, Heterocycles, 87 (10), 2037-2046, 2013.

Keiichi Konoki*, Tatsuya Onoda, Sachie Furumochi, Yuko Cho, Mari Yotsu-Yamashita, Takeshi Yasumoto, The binding of okadaic acid analogues to recombinant OABP2.1 originally isolated from the marine sponge Halichondria okadai, Bioorg. Med. Chem. Lett., 23, 5833-5835, 2013.

Takafumi Akimoto, Asako Masuda, Mari Yotsu-Yamashita, Takatsugu Hirokawa, and Kazuo, Nagasawa*, Synthesis of saxitoxin derivatives bearing guanidine and urea groups at C13 and evaluation of their inhibitory activity on voltage-gated sodium channel. Org. Biomol. Chem., 11, 6642-6649, 2013.

@ 

Mari Yotsu-Yamashita*, Yuka Abe, Yuta Kudo, Raphael Ritson-Williams, Valerie J. Paul, Keiichi Konoki, Yuko Cho, Masaatsu Adachi, Takuya Imazu, Toshio Nishikawa, and Minoru Isobe. First identification of 5,11-dideoxytetrodotoxin in marine animals, and characterization of major fragment ions of tetrodotoxin and its analogs by high resolution ESI-MS/MS. Marine Drugs 11, 2799-2813, 2013. Open access: (http://www.mdpi.com/1660-3397/11/8/2799/)@ doi:10.3390/md11082799

Mari Yotsu-Yamashita*, Natsumi Okoshi, Kouichi Watanabe, Nao Araki, Hiroe Yamaki, Yuki Shoji, and Takahiro Terakawa, Localization of pufferfish saxitoxin and tetrodotoxin binding protein (PSTBP) in the tissues of the pufferfish, Takifugu pardalis, analyzed by immunohistochemical staining, Toxicon, 72, 23-28, 2013.

Haruhiko Fuwa*, Masato Kawakami, Kenkichi Noto, akashi Muto, Yuto Suga, Keiichi Konoki, Mari Yotsu-Yamashita, Makoto Sasaki, Concise Synthesis and Biological Assessment of (+)-Neopeltolide and a 16-Member Stereoisomer Library of 8,9-Dehydroneopeltolide: Identification of Pharmacophoric Elements, Chem. Eur. J., 19, 8100-8110, 2013.

Kazuya Ishigai, Haruhiko Fuwa,* Keisuke Hashizume, Ryo Fukazawa, Yuko Cho, Mari Yotsu-Yamashita, and Makoto Sasaki*, Total Synthesis and Biological Evaluation of (+)-Gambieric Acid A and Its Analogues, Chem. Eur. J., 19, 5276-5288, 2013.

Yuko Cho*, Ryoko Ozeki, Mari Yotsu-Yamashita, and Yasukatsu Oshima, Single-cell analysis of paralytic shellfish toxins in Alexandrium tamarense by HPLC with post-column fluorescent derivatization Harmful Algae. Harmful Algae, 25, 47-53, 2013.

Keiichi Konoki*, Tatsuya Onoda, Ryuichi Watanabe, Yuko Cho, Shinnosuke Kaga, Toshiyuki Suzuki, and Mari Yotsu-Yamashita, In vitro Acylation of Okadaic Acid in the Presence of Various Bivalvesf Extracts. Marine Drugs, 11, 300-315, 2013 (Open access: http://www.mdpi.com/1660-3397/11/2/300)

Mari Yotsu-Yamashita*, Sawako Kondo, Shinya Segawa , Yi-chin Lin, Haruhiko Toyohara, Hisatomi Ito, Keiichi Konoki, Yuko Cho and Takafumi Uchida, Isolation and Structural Determination of Two Novel Phlorotannins from the Brown Alga Ecklonia kurome Okamura, and Their Radical Scavenging Activities, Marine Drugs, accepted 11, 165-183, 2013 (Open access: http://www.mdpi.com/1660-3397/11/1/165).

Noriyoshi Teramoto*, Hai-Lei Zhu, Mari Yotsu-Yamashita, Tetsuichiro Inai, Thomas C. Cunnane, Resurgent-like cur rents in mouse vas deferens myocytes are mediated by NaV1.6 voltage-gated sodium channels, Pfl_gers Archiv - European Journal of Physiology, 464, 493-502, 2012.

Dietrich Mebs*, Mari Yotsu-Yamashita, Hanns Martin Seitz, Osamu Arakawa, Tetrodotoxin does not protect red-spotted newts, Notophthalmus viridescens, from intestinal parasites. Toxicon, 60, 66-69, 2012.

Yuta Kudo, Takeshi Yasumoto, Keiichi Konoki, Yuko Cho, Mari Yotsu-Yamashita*, Isolation and structural determination of the first 8-epi-type tetrodotoxin analogs from the newt, Cynops ensicauda popei, and comparison of tetrodotoxin analogs profiles of this newt and the puffer fish, Fugu poecilonotus, Marine Drugs, 10, 655-667, 2012. (Open access: http://www.mdpi.com/1660-3397/10/3/655/)

Mari Yotsu-Yamashita, John Gilhen, Ronald W. Russell, Kenneth L. Krysko, Christian Melaun, Alexander Kurz, Silke Kauferstein, Dusan Kordis, Dietrich Mebs*, Variability of tetrodotoxin and of its analogues in the red-spotted newt, Notophthalmus viridescens (Amphibia: Urodela: Salamandridae), Toxicon, 59, 257-264, 2012.

Yoshikazu Kanai, Sadahiko Hiroki, Hiroyuki Koshino, Keiichi Konoki, Yuko Cho, Mirriam Cayme, Yasuo Fukuyo, and Mari Yotsu-Yamashita*, Identification of novel oxidized levuglandin D2 in marine red alga and mouse tissues. J. Lipid Res., 52 (12), 2245-2254, 2011.

Ryoko Shinohara, Osamu Iwamoto, Takafumi Akimoto, Mari Yotsu-Yamashita, Kaoru Yamaoka, and Kazuo Nagasawa*, Synthesis of skeletal analogs of saxitoxin derivatives and evaluation of their inhibitory activity on sodium ion channels Nav1.4 and Nav1.5. Chemistry- A European Journal, 17 (43), 12144-12152, 2011.

Eva Cagide, M Carmen Louzao, Bego_a Espi_a, Isabel Rodriguez Ares, Mercedes, R. Vieytes, Makoto Sasaki, Haruhiko Fuwa, Chihiro Tsukano, Yu Konno, Mari Yotsu-Yamashita, Leo A Paquette, Takeshi Yasumoto, and Luis M. Botana*, Chem. Res. Toxicol., 24(6), 835-842, 2011.

Q.T. Islam, M.A.Razzak, M.A.Islam, M.I.Bari, A.Basher, F.R.Chowdhury, A.B.M. Sayeduzzaman, H.A.M.N.Ahasan, M.A.Faiz, O.Arakawa, M. Yotsu-Yamashita, U.Kuch*, D.Mebs, Puffer fish poisoning in Bangladesh: clinical and toxicological results from large out breaks in 2008, Trans. Roy. Soc. Trop. Med. Hyg., 105, 74-80, 2011.

Mari Yotsu-Yamashita*, Jun-Ho Jang, Yuko Cho, Keiichi Konoki, Optimization for simultaneous analysis of tetrodotoxin, 4-epitetrodotoxin, 4,9-anhydrotetrodotoxin and 5,6,11-trideoxytetrodotoxin by hydrophilic interaction liquid chromatography-tandem mass spectrometry, Forensic Toxicol., 29, 61-64, 2011.

Keiichi Konoki,* Kaori Saito, Hiroki Matsuura, Naoyuki Sugiyama, Yuko Cho, Mari Yotsu-Yamashita, and Kazuo Tachibana, Binding of diarrheic shellfish poisoning toxins to okadaic acid binding proteins purified from the sponge Halichondria okadai, Bioorg. Med. Chem., 18 (21), 7607-7610, 2010.

Jun-Ho Jang, Jong-Soo Lee and Mari Yotsu-Yamashita*, LC/MS Analysis of Tetrodotoxin and Its Deoxy Analogs in the Marine Puffer Fish Fugu niphobles from the Southern Coast of Korea, and in the Brackishwater Puffer Fishes Tetraodon nigroviridis and Tetraodon biocellatus from Southeast Asia, Marine Drugs, 8, 1049-1058, 2010.

Dietrich Mebs*, Osama Arakawa, Mari Yotsu-Yamashita, Tissue distribution of tetrodotoxin in the red-spotted newt Notophthalmus viridescens, Toxicon, 55, 1353-1357, 2010.

Mari Yotsu-Yamashita* Hiroe Yamaki, Natsumi Okoshi and Nao Araki, Distribution of homologous proteins to puffer fish saxitoxin and tetrodotoxin binding protein in the plasma of puffer fish and among the tissues of Fugu pardalis examined by Western blot analysis, Toxicon, 55, 1119-1124, 2010.

Mari Yotsu-Yamashita* and Eiko Tateki, First report on toxins in the Panamanian toads Atelopus limosus, A. glyphus and A. certus, Toxicon, 55, 153-156, 2010.

Haruhiko Fuwa*, Asami Saito, Shinya Naito, Keiichi Konoki, Mari Yotsu-Yamashita, and Makoto Sasaki, Total Synthesis and Biological Evaluation of (+)-Neopeltolide and Its Analogues, Chem. Eur. J. 15, 12807-12818, 2009.

Mari Yotsu-Yamashita*, Analytical methods for tetrodotoxin and its analogs.  Journal of medical technology, 53 (6), 707-711, 2009. (in Japanese)

Jun-Ho Jang and Mari Yotsu-Yamashita*, Tetrodotoxin and 5,6,11-trideoxytetrodotoxin in Tetraodon nigroviridis and T. biocellatus collected from Southeast Asia, The proceedings of the 5th World Fisheries Congress (WFC), 2008.10.20-24 Yokohama. (Proceeding) 2008.

M. Carmen Louzao, Eva Cagide, Mari Yotsu-Yamashita, and Makoto Sasaki, Polycavernosides and Gambierol: Chemistry, Pharmacology, Toxicology, and Detection, in Seafood and Freshwater Toxins: Pharmacology, Physiology and detection (Food Science and Technology), Part VIIIE, Chaptor28, 597-628 (total 960 pages), Editor, Louis M. Botana, Crc Pr I Llc (Review), 2008.

Michiko Kono, Takashi Matsui, Kiyoshi Furukawa, Takuhiko Takase, Kunio Yamamori, Hideko Kaneda, Daisuke Aoki, Jun-Ho Jang, Mari Yotsu-Yamashita*, Examination of transformation among tetrodotoxin and its analogs in the living cultured juvenile puffer fish, kusafugu, Fugu niphobles by intramuscular administration, Toxicon, 52, 714-720, 2008.

Yuko Cho*, Noriyuki Ogawa, Miyako Takahashi, His-Pin Lin, Yasukatsu Oshima, Purification and characterization of paralytic shellfish toxin transforming enzyme, sulfocarbamoylase I, from Japanese bivalve, Peronidia venulosa. Biochimica et Biophysica Acta - Proteins and Proteomics, 1784 (2008), pp. 1277-1285.

Yuko Cho*, Kaori Hiramatsu, Motoo Ogawa, Takuo Omura, Takashi Ishimaru and Yasukatsu Oshima, Non-toxic and toxic subclones obtained from a toxic clonal culture of Alexandrium tamarense (Dinophyceae): Toxicity and molecular biological feature, Harmful Algae, 7 (2008), pp. 740-751. 

Michiko Kono*, Takashi Matsui, Kiyoshi Furukawa, Mari Yotsu-Yamashita, Kunio Yamamori, Accumulation of tetrodotoxin and@4,9-anhydrotetorodotoxin in cultured juvenile kusafugu Fugu niphobles by dietary administration of natural toxic komonfugu Fugu poecilonotus liver. Toxicon, 41, 1269-1273, 2008.

Satoshi Maruta, Kaoru Yamaoka and Mari Yotsu-Yamashita*, Two critical residues in p-loop regions of puffer fish Na+ channels on TTX-sensitivity, Toxicon, 51, 381-387, 2008.

Jun-Ho Jang and Mari Yotsu-Yamashita*, 6,11-Dideoxytetrodotoxin from the puffer fish, Fugu pardalis. Toxicon, 50, 947-851, 2007.

Leo A. Paquette and Mari Yotsu-Yamashita, Polycavernosides, In "Phycotoxins: chemistry and biochemistry", Captor 15, P275-296, 2007, Ames, Iowa, USA, Blackwell Publ. (Review)

Mari Yotsu-Yamashita, Dietrich Mebs*, Axel Kwet and Michael Schneider, Tetrodotoxin and its analogue 6-epitetrodotoxin in newts (Triturus spp.; Urodela, Salamandridae) from southern Germany, Toxicon, 50, 306-309, 2007.

Mari Yotsu-Yamashita*, Kazumi Abe, Tetsuya Seki, Kenshu Fujiwara, and Takeshi Yasumoto, Polycavernoside C and C2, the new analogs of the human lethal toxin polycavernoside A, from the red alga, Gracilaria edulis, Tetrahedron Lett. 48, 2255-2259 (2007)

Mari Yotsu-Yamashita, Dietrich Mebs* and Wolfgang Flachsenberger, Distribution of tetrodotoxin in the body of the blue-ringed octopus (Hapalochlaena maculosa) Toxicon, 49, 410-412 (2007).

E. Cagide1, M.C. Louzao1, I.R. Ares1, M.R. Vieytes2, M. Yotsu-Yamashita3, L.A. Paquette4, T. Yasumoto5 and L.M. Botana1,* EFFECTS OF A SYNTHETIC ANALOG OF POLYCAVERNOSIDE A ON HUMAN NEUROBLASTOMA CELLS, Cell Physiol. Biochem., 19, 185-194 (2007).

Mitsugu Akagawa, Yoshihisa Ishii, Takeshi Ishii, Takashiro Shibata, Mari Yotsu-Yamashita, Kyozo Suyama, and Koji Uchida*, Metal-catalyzed oxidation of protein-bound dopamine, Biochemistry, 2006, 45, 15120-15128.

Tomoko Aoki, Daisuke Sasaki, Mitsugu Akagawa, Kyozo Suyama, and Mari Yotsu-Yamashita*, Application of Lysyl Oxidase Activity in Egg Shell Membrane of Hen to Selective Oxidation of e-Amino Group in Lysine to Aldehyde in Short Peptides, Peptide Science 2006, 126. H. Ishida and H. Mihara (Ed.) The Japanese peptide society

Akagawa, M*., Sasaki, D., Ishii, Y., Kurota, Y., Yotsu-Yamashita, M., Uchida, K., and Suyama, K. Chem. Res. Toxicol.19, 1059-1065 (2006).

Junho Jang and Mari Yotsu-Yamashita*, Distribution of tetrodotoxin, saxitoxin, and their analogs among tissues of the puffer fish Fugu pardalis. Toxicon 48, 980-987 (2006).

Louzao, M. C., Vieytes, M. R., Yasumoto, T., Yotsu-Yamashita, M., and Botana, L. M.,* Changes in membrane potential: An early signal triggered by neurologically active phycotoxins. Chem. Res. Toxicol., 19, 788-793 (2006) .

MariYotsu-Yamashita, Spectroscopic study of the structure of zetekitoxin AB, Marine Natural Products Series: Topics in Heterocyclic Chemistry, Vol. 5, 53-65 Kiyota, Hiromasa (Ed.), Publisher: Springer-Verlag GmbH (2006).

Toshio Nakagawa, Junho Jang, and Mari Yotsu-Yamashita*, Hydrophilic interaction liquid chromatography-electrospray ionization mass spectrometry of tetrodotoxin and its analogs, Anal. Biochem., 352, 142-144 (2006).

Raphael Ritson-Williams*, Mari Yotsu-Yamashita, and Valerie Paul, Ecological functions of tetrodotoxin in a deadly polyclad flatworm, Proc. Natl. Acad. Sci. USA, 103 (9) 3176-3179 (2006).

Mari Yotsu-Yamashita* and Daisuke Sasaki, Identification of the cyclic aminal forms of a-aminoadipic and g-glutamic semialdehydes as the major forms in aqueous solution, Peptide Science 2004: Y. Shimohigashi (Ed.) The Japanese peptide society 435-436 (2005).

Mari Yotsu-Yamashita*, Ayako Goto, and Toshio Nakagawa, Isolation of 4-S-cysteinyltetrodotoxin from the liver of the puffer fish Fugu pardalis, and formation of the adducts of 4,9-anhydrotetrodotoxin with thiols, Chem. Res. Toxicol. 18, 865-871(2005).

Mari Yotsu-Yamashita*,  Takeshi Yasumoto, Shunichi Yamada , Fe Farida A. Bajarias, Mirriam A. Formelozsa|, Marc Lawrence Romero, and Yasuo Fukuyo|| Identification of polycavernosides A as the causative agent of the fatal food poisoning resulting from ingestion of the red alga Gracilaria edulis in Philippines, Chem. Res. Toxicol. 17, 1265-1271 (2004).

Mari Yotsu-Yamashita, "Possible mechanism for resistibility of puffer fish against tetrodotoxin", Jpn. J. Physiol., 54, Suppl., S13 (2004).

Mari Yotsu-Yamashita*, Yong H. Kim*, Samuel C. Dudley Jr., Gaurav Choudhary, Arnold Pfahnl, Yasukatsu Oshima and John W. Daly, Ҽ/span>The structure of zetekitoxin AB, a saxitoxin analog from the golden frog Atelopus zeteki:: a potent sodium channel blockerӼ/span>. Proc. Natl. Acad. Sci. USA, 101 (13), 4346-4351 (2004).

Yong Hae Kim and Mari Yotsu-Yamashita, Ҽ/span>Potent neurotoxins: Tetrodotoxin, chiriquitoxin, and zetekitoxin from Atelopus frogs of Central AmericaӼ/span>, J. Toxicol. Toxin Reviews, 22 (4), 521-532, 2003.

Mari Yotsu-Yamashita and Dietrich Mebs*, Ҽ/span>Occurrence of 11-oxotetrodotoxin in the red-spotted newt, Notophthalmus viridescens, and further studies on the levels of tetrodotoxin and its analogues in the newt eftsӼ/span>, Toxicon, 41, 893-897, 2003.

Mari Yotsu-Yamashita*, Daisuke Urabe, Masanori Asai, Toshio Nishikawa and Minoru Isobe, Ҽ/span>Biological activity of 8,11-dideoxytetrodotoxin: Lethality to mice and the inhibitory activity to cytotoxicity of ouabain and veratridine in mouse neuroblastoma cells, Neuro-2aӼ/span>, Toxicon, 42, 557-560, 2003.

Gaurav Choudhary, Mari Yotsu-Yamashita, Lisa Shang, Takeshi Yasumoto and Samuel C. Dudley, Jr.*, Ҽ/span>Interactions of C-11 Hydroxyl of Tetrodotoxin with the Sodium Channel Outer VestibuleӼ/span>, Biophys. J., 84, 287-294, 2003.

Misako Tagiri-Endo, Kaori Ono, Kiyotaka Nakagawa, Mari Yotsu-Yamashita and Teruo Miyazawa,* Ҽ/span>Ozonation of phosphatidylcholine in ethanol: separation and identification of a novel ethoxyhydroperoxideӼ/span>, Lipids, 37 (10), 1007-1012, 2002.

Mari Yotsu-Yamashita, Sodium Channels of Puffer Fish, Nippon Suisan Gakkaishi, 68 (6), 925-926, 2002.

Mari Yotsu-Yamashita, Yuki Shoji, Takahiro Terakawa, Shunichi Yamada, Teruo Miyazawa and Takeshi Yasumoto, Ҽ/span>Mutual inhibition of tetrodotoxin and saxitoxin binding to their binding protein from plasma of the puffer fish, Fugu pardalisӼ/span>, Biosci. Biotechnol. Biochem., 66 (11), 2520-2524, 2002. 

Mari Yotsu-Yamashita, Atsuko Sugimoto, Takahiro Terakawa, Yuki Shoji, Teruo Miyazawa and Takeshi Yasumoto, Ҽ/span>Purification, chracterization, and cDNA cloning of a novel soluble saxitoxin and tetrodotoxin binding protein from plasma of the puffer fish, Fugu pardalisӼ/span>, Eur. J. Biochem, 268 (22), 5937-5946, 2001.

Mari Yotsu-Yamashita, Ҽ/span>Chemistry of puffer fish toxinӼ/span>, J. Toxicol. Toxin Reviews, 20 (1), 51-66, 2001. 

Mari Yotsu-Yamashita and Dietrich Mebs, Ҽ/span>The levels of tetrodotoxin and its analogue 6-epitetrodotoxin in the red-spotted newts, Notophthalmus viridescens, Toxicon, 39, 1261-1263, 2001.

Yuki Shoji, Mari Yotsu-Yamashita, Teruo Miyazawa and Takeshi Yasumoto, Ҽ/span>Electrospray Ionization Mass Spectrometry of Tetrodotoxin and its Analogs: Liquid Chromatography/ Mass Spectrometry, Tandem Mass Spectrometry, and Liquid Chromatography/Tandem Mass SpectrometryӼ/span>, Anal. Biochem., 290 (1), 10-17, 2001.

Mari Yotsu-Yamashita, Katsuhiko Nishimori, Yoko Nitanai, Masako Isemura, Atsuko Sugimoto and Takeshi Yasumoto, Ҽ/span>Binding Properties of 3H-PbTx-3 and 3H-saxitoxin to Brain Membranes and to Skeletal Muscle Membranes of Puffer Fish Fugu pardalis, and the Primary Structure of a Voltage-Gated Na+ Channel a-Subunit (fMNa1) from Skeletal Muscle of F. pardalisӼ/span>, Biochem. Biophys. Res. Commun., 267 (1), 403-412, 2000. 

E. J. Nunez-Vazquez, M. Yotsu-Yamashita, A. P. Sierra-Beltran, T. Yasumoto and J. L. Ochoa, "Toxicities and distribution of tetrodotoxin in the tissues of puffer fish found in the coast of the Baja California Peninsula, Mexico", Toxicon, 38, 729-734, 2000.

Charles T. Hanifin, Mari Yotsu-Yamashita, Takeshi Yasumoto, Edmund D. Broodie III and Edmund D. Broodie Jr., "Toxicity of dangerous prey:variation of tetrodotoxin levels within and among populations of the newt Taricha granulosa ", J. Chem. Ecology, 25, 2161-2175, 1999.

Louis Barriault, Serge L. Boulet, Kenshu Fujiwara, Akio Murai, Leo A. Paquette and Mari Yotsu-Yamashita, "Synthesis and biological evaluation of analogs of the marine toxin polycavernoside A", Bioorg.& Med.Chem. Lett., 9, 2069-2072, 1999.

Mari Yotsu-Yamashita, Atsuko Sugimoto, Akira Takai and Takeshi Yasumoto, "Effects of Specific Modifications of Several Hydroxyls of Tetrodotoxin on its Affinity to Rat Brain Membrane", J. Pharmacol. Exp. Ther., 289 (3), 1688-1696, 1999.

Mari Yotsu-Yamashita, Bernhard Schimmele and Takeshi Yasumoto, "Isolation and Structural Assignment of 5-Deoxytetrodotoxin from the Puffer Fish, Fugu poecilonotus ", Biosci. Biotechnol. Biochem., 63, 961-963, 1999.