Stereochemical Investigations of Isochromenones and Isobenzofuranones Isolated from Leptosphaeria sp. KTC 727
Stereochemical Investigations of Isochromenones and Isobenzofuranones Isolated from Leptosphaeria sp. KTC 727
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DOI：
10.1021/np100838j
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发表时间：
2011-03-01
影响因子：
5.1
通讯作者：
Hashimoto, Masaru
中科院分区：
文献类型：
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作者：
Tayone, Wilanfranco C.;Honma, Miho;Hashimoto, Masaru
从钩端螺旋体发酵液中分离得到两个新的代谢产物(R)-3，4-dihydro-4，6，8-trihydroxy-4，5-dimethyl-3-methyleneisochromen-1-one(1)和(R)-7-hydroxy-3，4(S)-1-hydroxyethyl)-5-methoxy-3，4-dimethylisobenzofuran-1(3H)-one(2)，以及两个结构已知的相关化合物(3和4)。KTC727(JCM 13076=MAFF 239586)。这些结构主要通过(1)H和(13)C核磁共振波谱分析来揭示。通过NOE研究确定了2的相对构型。通过改进的Mosher方法和衍生化后的CD光谱相结合，确定了该分子的绝对构型。理论上的光盘简介也支持这些任务。结构相关性使我们能够确定代谢物1、3和4的绝对构型，其中后两个的构型尚未建立。其中化合物2的抑菌活性最强，当浓度为0.5µg/mL时，对棉球菌丝生长的抑制作用最强。
Two new metabolites, (R)-3,4-dihydro-4,6,8-trihydroxy-4,5-dimethyl-3-methyleneisochromen-1-one (1) and (R)-7-hydroxy-3,4(S)-1-hydroxyethyl)-5-methoxy-3,4-dimethylisobenzofuran-1(3H)-one (2), were isolated along with two structurally known related compounds (3 and 4) from the culture broth of Leptosphaeria sp. KTC 727 (JCM 13076 = MAFF 239586). These structures were disclosed mainly with (1)H and (13)C NMR spectroscopic analyses. The relative configuration of 2 was established by NOE studies. The absolute configuration of this molecule was determined by a combination of the modified Mosher's method and CD spectra after derivatizations. The theoretical CD profiles also supported these assignments. Structural correlations enabled us to establish the absolute configurations of metabolites 1, 3, and 4, in which configurations of the latter two had not been established. Compound 2 exhibited the strongest antifungal activity among them, inhibiting the hyphal growth of Cochliobolus miyabeanus at about 0.5 mu g/mL.