Sprogøe Kennett, Staek Dan, Ziegler Hanne L, Jensen Thomas Høgh, Holm-Møller Søren B, Jaroszewski Jerzy W
Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark.
J Nat Prod. 2008 Apr;71(4):516-9. doi: 10.1021/np800010r. Epub 2008 Feb 14.
Despite recent demonstration of the power of HPLC-PDA-MS-SPE-NMR (high-performance liquid chromatography-photodiode-array detection-mass spectrometry-solid-phase extraction-nuclear magnetic resonance) in structure determination of natural products directly from minute amounts of crude extracts, this technique leaves chirality of the compounds uncharacterized. In this work we demonstrate that postcolumn SPE is a useful method of analyte concentration and accumulation not only for NMR but also for CD (circular dichroism) spectroscopy. Thus, use of HPLC-PDA-MS-SPE-NMR in combination with CD allowed rapid detection of ( R)-(-)-gossypol [( R)- 1] in Thespesia danis, providing a very rare example of the predominance of the levorotatory enantiomer of gossypol. Enantioselectivity of the in vitro antiplasmodial activity of gossypol was also demonstrated; the IC50 value of ( R)- 1 was 4.5 +/- 0.2 microM, with the eudismic ratio of about 2.5. No gossypol was detected in Gossypioides kirkii.
尽管最近已证明高效液相色谱 - 光电二极管阵列检测 - 质谱 - 固相萃取 - 核磁共振（HPLC - PDA - MS - SPE - NMR）技术在直接从微量粗提物中测定天然产物结构方面的强大功能，但该技术无法确定化合物的手性。在本研究中，我们证明柱后固相萃取不仅是一种用于核磁共振分析物浓缩和富集的有用方法，而且对圆二色光谱（CD）也很有用。因此，将HPLC - PDA - MS - SPE - NMR与CD联用，能够快速检测出丹宁桐（Thespesia danis）中的（R）-（ - ）-棉酚[（R）-1]，这是左旋对映体棉酚占优势的一个非常罕见的例子。同时也证明了棉酚体外抗疟活性的对映体选择性；（R）-1的半数抑制浓度（IC50）值为4.5±0.2微摩尔，优级比约为2.5。在基氏棉葵叶棉（Gossypioides kirkii）中未检测到棉酚。
