79(PB2-9) 下痢性貝毒に関連した新有毒成分yessotoxinの単離と構造(ポスター発表の部)

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Previously we isolated the causative agents and determined their structures to be okadaic acid derivatives and novel polyether lactones, pectenotoxin. From the scallop, Patinopecten yessoensis collected in Mutsu Bay, 1986, a new toxic constituent was isolated and named yessotoxin (YTX, I). The toxin exceed the known diarrhetic shellfish toxins in toxicity (100μg/kg, mice, i.p.). The structure was determined mainly by modern NMR techniques, including COLOC, PS-NOESY and ROESY. The connectivities of the protons were established with use of ^1H-^1H COSY and RELAY although the spin system was disconnected by five quaternary carbons. The COLOC sequence was effective to assemble the fragments into a single carbon chain because ^<13>C-^1H two- and three-bond couplings between terminal protons and/or carbons of the fragments, and the quaternary carbons and/or the adjacent methyls are detectable by the sequence. Positions of ether-bonds were determined by the COLOC and NOE measurements with use of phase sensitive (PS) NOESY and ROESY. Three-bond couplings across ether linkages of rings E, G and K were observed in the COLOC spectra. The other ether rings were assigned mainly by NOE's detected on the axial protons or methyls adjacent to juncture carbons. Stereochemistry of YTX was deduced as shown in Fig. 6 mainly by NOE experiments. Detailed analyses of NOE's around seven- and eight-membered rings enabled us to deduce that their conformations take the boat and the boat-chair forms, respectively. Stereo-chemistry of an acyclic asymmetric carbon at 41 is also speculated on the basis of the NOE's observed between protons on rings J or K, and CH_3-C41 or H-41.
天然有機化合物討論会の論文
1987-07-25

79(PB2-9) 下痢性貝毒に関連した新有毒成分yessotoxinの単離と構造(ポスター発表の部)

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