Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa-ku, Nagoya 464-8601, Japan.
Bioorg Med Chem. 2012 Jan 15;20(2):687-92. doi: 10.1016/j.bmc.2011.12.012. Epub 2011 Dec 14.
A new 10-membered-ring diterpene, cyclolobatriene (1), along with three other known diterpenes, lobatriene (2), eunicol (3), and fuscol (4), were isolated from the Okinawan soft coral Lobophytum pauciflorum. Their structures were established by extensive NMR spectroscopic analyses. Cyclolobatriene (1) is an additional example of rare prenylated germacrenes. Although 1, due to a 10-membered-ring structure, exists as an equilibrium mixture of three conformers, the NMR measurement in CDCl(3) at 7°C enabled us to assign the NMR signals of the three, which is the first example of the complete NMR assignment of all the existing conformers of germacrene-type compounds. Cyclolobatriene (1) was thermally unstable and converted into 2 through Cope rearrangement upon heating at 70°C. Eunicol (3) also possesses the same prenylated germacrene structure as 1, showing similar physico-chemical properties to 1. All four compounds 1-4 showed cytotoxic effect with IC(50)'s of 0.64, 0.41, 0.35 and 0.52 μM, respectively, against human epidermoid carcinoma A431 cells.
从冲绳软珊瑚 Lobophytum pauciflorum 中分离得到了一种新的 10 元环二萜环洛巴烯（1），以及另外三种已知的二萜洛巴烯（2）、艾里醇（3）和 Fuscol（4）。通过广泛的 NMR 光谱分析确定了它们的结构。环洛巴烯（1）是罕见的prenylated germacrenes 的另一个例子。尽管 1 由于 10 元环结构，存在三种构象的平衡混合物，但在 CDCl3 中于 7°C 的 NMR 测量使我们能够分配三种构象的 NMR 信号，这是首次对所有存在的 Germacrene 型化合物的构象进行完整的 NMR 分配。环洛巴烯（1）在 70°C 加热时通过 Cope 重排不稳定，并转化为 2。艾里醇（3）也具有与 1 相同的prenylated germacrene 结构，表现出与 1 相似的物理化学性质。四种化合物 1-4 对人表皮癌细胞 A431 均具有细胞毒性作用，IC50 分别为 0.64、0.41、0.35 和 0.52 μM。
