34 らん藻Anabaena flos-aguaeのコリンエステラーゼ阻害物質anatoxin-a(s)(口頭発表の部)  [in Japanese] 34 Anatoxin-a(s), a Potent Anticholinesterase from Anabaena flos-aquae  [in Japanese]

Anatoxin-a(s) is a neurotoxic alkaloid associated with the blue-green alga Anabaena flos-aquae. Its potent toxicity (LD_<50> 20-40μg/kg mice) is attributed to exceptional anticholinesterase activity. Acidic alcoholic extract of the freeze-dried alga was subjected to patitioning and extraction with acidic alcoholic solutions to give a toxic concentrate. Gel filtration on Toyopearl HW40F (Supelco) followed by HPLC on CN and ODS columns gave pure anatoxin a(s) as a colorless solid in 0.05% yield. The gross structure of anatoxin a(s) was determined by spectroscopic method on the toxin itself and on the degradation products. NMR data of the ^<13>C and ^<15>N enriched toxin were indispensable for the work. The absolute configuration of anatoxin a(s) was elucidated by synthesizing one of the degradation products from L-Asn.