New lamellarin alkaloids from the Australian ascidian, Didemnum chartaceum
New lamellarin alkaloids from the Australian ascidian, Didemnum chartaceum
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DOI：
10.1021/np9803530
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发表时间：
1999-03-01
影响因子：
5.1
通讯作者：
Quinn, RJ
中科院分区：
文献类型：
--
作者：
Davis, RA;Carroll, AR;Quinn, RJ
从大堡礁海鞘(Didemnum Chartaceum)中分离得到5个新的片层素类生物碱。通过对光谱数据的解释，确定了薄层蛋白B、C和L的20-硫酸酯衍生物(1-3)，薄层多糖G的8-硫酸酯衍生物(4)，以及非硫酸酯化合物薄层多糖Z(5)的结构。片麻素G 8-硫酸盐(4)是这类化合物的第一个在C-8位硫化的例子，而片麻素Z(5)是二甲氧基化的片麻素的第一个例子。已知的薄层菌素A、B、C、E、G和L(6-11)，以及薄膜菌素D(12)和N(13)的三乙酸酯衍生物也被分离出来。薄层蛋白B、C和L(1-3)的20-硫酸基衍生物的H-1核磁共振谱中信号积分的异常导致了核磁共振弛豫研究。计算了硫酸盐化的片层蛋白(1-4)及其相应的非硫酸盐衍生物(7、8、10、11)中所有质子的T-1值。有趣的是，化合物(1-4)中与硫酸盐基团相邻的质子的T-1值比其非硫酸盐衍生物(7，8，10，11)中相应的质子大五倍。
Five novel lamellarin-class alkaloids have been isolated from a Great Barrier Reef ascidian, Didemnum chartaceum. The structures of the 20-sulfated derivatives of lamellarins B, C, and L (1-3); the 8-sulfated derivative of lamellarin G (4), plus a nonsulfated compound, lamellarin Z (5), were identified by interpretation of spectroscopic data. Lamellarin G 8-sulfate (4) is the first example of this class of compounds sulfated at the C-8 position, while lamellarin Z (5) is the first example of a dimethoxylated lamellarin. The known lamellarins A, B, C, E, G, and L (6-11), plus the triacetate derivatives of lamellarins D (12) and N (13), were also isolated. An aberration in the integration of signals in the H-1 NMR spectra of the 20-sulfated derivatives of lamellarins B, C, and L (1-3) led to NMR relaxation studies. T-1 values were calculated for all protons in the sulfated lamellarins (1-4) and their corresponding nonsulfated derivatives (7, 8, 10, 11). Interestingly, the protons ortho to the sulfate group in compounds (1-4) had T-1 values up to five times larger than the corresponding protons in their nonsulfated derivatives (7, 8, 10, 11).