Study of Convulsive Brasiliamides from Penicillium brasilianum Batista JV-379

以巴西青霉Batista JV-379土壤分离物发酵的豆渣为原料，采用活性引导分离的方法分离得到了新的惊风化合物巴西利亚酰胺A和B。根据光谱和化学证据以及巴西酰胺B氢化产物的x射线晶体学对其结构进行了分析。巴西酰胺B的^1H-和^<13>C-NMR谱显示，信号复杂，在室温下，在几种氘化溶剂中均被加倍或展宽。通过不同温度下的核磁共振测量，阐明了巴西利亚酰胺B的构象变化为酰胺键在溶液中的旋转异构化。在CDCl_3中，在-60℃下，巴西酰胺B的两个酰胺键上有四个旋构象，而在室温下，由于其中一个酰胺键的快速旋转，只出现了两个异构体。此外，还分离得到了3个新的巴西利亚酰胺同源物——巴西利亚酰胺C、D和E，并确定了它们的结构。巴西木酰胺A、B和C分别对ED_<50>值为300、50和300 μg/g的家蚕具有惊厥活性。

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.