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Synthesis of a Tricyclic Bisguanidine Compound Structurally Related to Saxitoxin and its Identification in Paralytic Shellfish Toxin‐Producing Microorganisms
Author(s) -
Tsuchiya Shigeki,
Cho Yuko,
Konoki Keiichi,
Nagasawa Kazuo,
Oshima Yasukatsu,
YotsuYamashita Mari
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201500064
Subject(s) - saxitoxin , toxin , tricyclic , chemistry , microorganism , paralytic shellfish poisoning , biochemistry , shellfish , stereochemistry , biology , bacteria , aquatic animal , fishery , fish <actinopterygii> , genetics
We recently reported the chemical synthesis and identification of the genetically predicted biosynthetic intermediates of saxitoxin (STX), including a 2‐aminoimidazole‐bearing monoguanidine compound (Int‐C′2) in two paralytic shellfish toxin (PST)‐producing microorganisms. In this study, we achieved the direct conversion of Int‐C′2 into a tricyclic bisguanidine compound (called Cyclic‐C′), which is structurally related to STX, through oxidative intramolecular guanidine transfer to 2‐aminoimidazole catalyzed by Pd/C under basic conditions in air. By using HPLC‐MS analysis, Cyclic‐C′ was also identified in the PST‐producing microorganisms, suggesting that Cyclic‐C′ is either another biosynthetic intermediate or a shunt product of PSTs. In addition, a weak inhibitory activity of Cyclic‐C′ to the voltage‐gated sodium channels was detected by using a cell‐based assay.