P-7 Cryptosporiopsis abietinaの生産する新規ステロド : Abscisterol類の構造(ポスター発表の部)

抄録

The resinous stem canker of Chamaecyparis obtusa Sieb. et Zucc., which has long been well-known among Japanese foresters but whose cause was unknown, and recently Kobayashi et. al. reported that Cryptosporiopsis abietina causes this disease. We isolated some sterols which indicate the abscisic activity against C. obtusa leaves, from the n-hexane extract of acetone soluble fraction of cultured C. abietina mycelium. We report here, the structure elucidation of abscisterol A-F (1-6) and 21-oic acid type sterol (7) by a series of 1D and 2D NMR experiments and an advanced Mosher method. The major component 1 has novel 21-nor-Δ^<17(20)>-double bond and 4β,19-ether bond. 2,4,5 also have 21-nor-Δ^<17(20)>-double bond. Only 7 has 21-carbon in abscisterol family as carboxyl group. Though a few naturally occurring Δ^<17(20)>-unsaturated sterols have been described, all of them possess 21-carbon. It is assumed that 21-nor-Δ^<17(20)>-double bond of abscisterols is formed from 21-oic acid precursor with decarboxylation. It is the first report of nor-21-Δ^<17(20)>-sterols from nature.