14 β-グルカン阻害剤の真菌類からの検索(口頭発表の部)

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The cell wall of plant pathogenic fungi Phytophthora is mainly composed of highly branched β-(1,3)glucan. We realized that this typical cell wall composition should be useful to investigate the inhibitor of β-(1.3)glucan synthesis. The culture filtrates derived from fungi were screened with the objective of detecting any morphological change that might be occurring in hyphae. On the basis of our screening, four strains of fungi, Hemicarpenteles acanthosporus, Hemicarpenteles paradoxus, Bipolaris sp. and Acremonium strictum, were found to produce active compounds which induced highly branched and noded hyphae to P. capsici The active principles isolated from the culture filtrates of H. acanthosporus, H. paradoxus and Bipolaris sp. were identified as (+)-isoepoxydon(2)(minimum dose activity inducing morphological change 100 μg/disc), brefeldin A(2)(50 μg/disc) and ophiobolin A(4)(10 μg/disc) respectively. Accompanied with brefeldin A, 7-oxobrefeldin A(3) was also isolated, however, it only showed growth inhibitory activity. (+)-Isoepoxydon and ophiobolin A showed equivqlent activity of ID50 at a concentration of 50 μg/ml and 25 μg/ml respectively with the regard to inhibition test using UDP-glucose and β-(1,3)glucan synthase prepared from baker's yeast. A yellow coloured compound was isolated from the culture filtrate of A. strictum and its molecular formula was determined by HR-FABMS as C28H32O9. This compound was revealed to be identical to bisvertinolone(6), however, we revised the structure as (5). Using NOE experiment and CD spectrum, we determined the absolute stereochemistry of this compouned as (7). This compound showed strong activity in vivo(10 μg/disc), however, it showed weak inhibitory activity in vitro(400 μg/ml). Therefore, we are now investigating the inhibitory activity to β-(1,6)glucan synthesis.
天然有機化合物討論会の論文
1990-09-25

14 β-グルカン阻害剤の真菌類からの検索(口頭発表の部)

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