Tayone Wilanfranco C, Kanamaru Saki, Honma Miho, Tanaka Kazuaki, Nehira Tatsuo, Hashimoto Masaru
The United Graduate School of Agricultural Sciences, Iwate University, Morioka, Japan.
Biosci Biotechnol Biochem. 2011;75(12):2390-3. doi: 10.1271/bbb.110621. Epub 2011 Dec 7.
A novel isochromanone, (S)-8-hydroxy-6-methoxy-4,5-dimethyl-3-methylene-isochromen-1-one (1), known 2 and previously reported metabolites from Leptosphaeria sp. KTC 727 (JCM 13076 = MAFF 239586) were isolated from the same source by culturing for a relatively long period. The results of the present study disclose their structures involving the absolute stereochemistry. The planar structures of these molecules were established by ESIMS and NMR spectral analyses. The absolute configuration of 1 was established by comparing its electronic circular dichroism (ECD) spectrum with that of structurally-related known compound 3. The relative stereochemistry of 2 was revealed by a combination of nuclear Overhauser effect (NOE) experiments and thermodynamic discussions. Successful transformation of 1 to 2 led us to assign the configuration of 2 after comparing their ECD spectra. These compounds exhibited weak antifungal activities against Cochliobolus miyabeanus.
一种新型异色满酮，(S)-8-羟基-6-甲氧基-4,5-二甲基-3-亚甲基异色满-1-酮（1），以及已知的化合物2和先前报道的来自小球腔菌属KTC 727（日本典型培养物保藏中心13076 = 日本农林水产省239586）的代谢产物，通过较长时间的培养从同一来源中分离得到。本研究结果揭示了它们的结构，包括绝对立体化学。这些分子的平面结构通过电喷雾离子化质谱（ESIMS）和核磁共振光谱分析得以确定。通过将化合物1的电子圆二色光谱（ECD）与结构相关的已知化合物3的ECD光谱进行比较，确定了化合物1的绝对构型。通过核Overhauser效应（NOE）实验和热力学讨论相结合的方法，揭示了化合物2的相对立体化学。在比较化合物1和2的ECD光谱后，成功地将化合物1转化为化合物2，从而确定了化合物2的构型。这些化合物对宫部旋孢腔菌表现出较弱的抗真菌活性。
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