Study of Convulsive Brasiliamides from Penicillium brasilianum Batista JV-379

从巴西青霉(Penicillium brasilianum Batista JV-379)土壤分离株发酵的欧卡拉中分离得到新的惊厥类化合物B和B。根据光谱和化学证据以及氢化产物的X-射线结晶学确定了它们的结构。在~1H和~1t；13~gt；C-核磁共振谱中，它们的信号很复杂，在室温下都在几种氢化溶剂中被倍增或展宽。通过不同温度下的核磁共振测量，确定了B的构象变化为酰胺键在溶液中的旋转异构化。在CdCl3中，在-60℃时，在两个酰胺键上出现了四个Brasiliamide B的旋转异构体，而在室温下，由于其中一个酰胺键的快速旋转，只有两个异构体出现。此外，还分离得到了3个新的巴西菊内酯同系物：巴西威廉内酯C、D和E，并确定了它们的结构。对家蚕有惊厥活性，ED_(50)为300、50和300μg/g饲料。

New convulsive compounds, brasiliamides A and B, were isolated by activity-guided fractionation from okara fermented with a soil isolate of Penicillium brasilianum Batista JV-379. Their structures were elucidated on the basis of spectral and chemical evidence and by X-ray crystallography of the hydrogenated product of brasiliamide B. In the ^1H- and ^<13>C-NMR spectra of brasiliamide B, the signals were complicated, all being doubled or broadened in several deuterated solvents at room temperature. The conformational change of brasiliamide B was clarified as the rotational isomerization of amide bonds in solution by NMR measurements at various temperatures. Four rotamers of brasiliamide B at two amide bonds were presented at -60℃ in CDCl_3, whereas only two isomers were apparent at room temperature, owing to rapid rotation of one of the amide bonds. Additionally, three new brasiliamides congeners, brasiliamides C, D and E were isolated and their structures were determined. Brasiliamides A, B and C respectively showed convulsive activity against silkworms with ED_<50> values of 300, 50 and 300 μg/g of diet.