抄録
In the course of our studies on biologically active fungal metabolites, we obtained an isolate of Penicillium brasilianum Batista JV-379, which showed convulsive activity against silkworm (Bombvx mori), from soil samples collected around Sakai. By using a bioassay-guided separation, two active principles (1 and 2) were isolated from okara fermented with the strain. The structure of 1 was elucidated to be N^1, N ^2-diacetyl-N^2-(2-oxo-3-phenylpropy1)-3-(5-methoxy-3,4-methylenedioxyphenyl)-1,2-propenediamine by spectroscopic methods, and named brasiliamide A. In ^1H and ^<13>C NMR spectra of 2, signals were complicated with almost of all signals doubled in several deuterated solvents at room temperature. As the conformational change of 2 in solutions was revealed on NMR spectra at various temperatures, a major component of 2 in C_6D_6 was analyzed by 2D NMR methods. It was further proved that four conformational isomers of 2 existed as rotamers on two amide bonds at -60℃. The structure of 2 was presumed to be 1,4-diacetyl-2-benzyl-5-(5-methoxy-3,4-methylenedioxybenzyl)-1,2,3,4-tetrahydropyrazine and was finally determined by X-ray crystallography on a hydrogenation product of 2. Compounds 1 and 2 showed convulsion against silkworm, and their activity were evaluated as ED_<50> values 300 and 50μg/g of diet, respectively.
