33 チモシーがまの穂病病徴部の抗菌物質(口頭発表の部)  [in Japanese] 33 ANTIFUNGAL COMPOUNDS FROM STROMATA OF EPICHLOE TYPHINA ON PHLEUM PRATENSE  [in Japanese]

Choke disease fungus Epichloe typhina is associated with resistance to leaf spot disease in timothy plants (Phleum pratense). We have proposed the hypothesis that this resistance is caused by antifungal compounds existing in infected plants. We investigated the fungitoxic constituents of the stromata of E. typhina. Seventy-eight compounds were isolated, including twenty novel sesquiterpenoids chokols (1,2,7-17,19-21,23-26), five novel oxygenated fatty acids(27-31), gamahonolide A(34) and B(37), gamahorin(38) and non-fungitoxic chokorin(71) and an anthrasteroid(80). Their structures were determined by spectroscopic methods. The absolute configuration of chokol E(2) was elucidated by its CD spectrum with Eu(fod)_3 and a chemical correlation with epicyclonerodiol oxide(5). Phytol(81), phytyl acetate(82) and phytyl palmitate(83) were identified as an inducer of aerial hyphae formation of Cladosporium herbarum. Pinoresinol(60) and diosmetin(73) were metabolized in cultures of E. typhina. Pinoresinol(60) was transformed into C6 norlignan(59) and α-ribofuranoside(87). Diosmetin(73) was transformed into 7-O-α-ribofuranoside(88). Antifungal activities of the isolated compounds were investigated.