Lin Chen-Hsing, Fang Wei-Ru, Kuo Chia-Ming, Chang Wing-Yao, Liu Yu-Chih, Lin Wann-Yin, Wu Jong-Chang, Lin Ching-Erh
Department of Applied Chemistry, Fooyin University, Ta-Liao, Kaohsiung County 831, Taiwan.
J Chromatogr A. 2008 Apr 25;1188(2):301-7. doi: 10.1016/j.chroma.2008.02.074. Epub 2008 Feb 29.
Chiral separations of three hydroxyflavanone aglycones, including 2'-, 3'-, and 4'-hydroxyflavanone, in capillary zone electrophoresis (CZE) using randomly sulfate-substituted beta-cyclodextrin (S-beta-CD) or dual cyclodextrin (CD) systems consisting of S-beta-CD and a neutral CD at low pH were investigated. The results indicate that S-beta-CD is an excellent chiral selector for enantioseparation of 2'-hydroxyflavanone and is a good chiral selector for 3'-hydroxyflavanone. Depending on the concentration of S-beta-CD ranging from 2.0 to 0.75% (w/v), the enantioresolution values were 10.5-19.5 and 1.8-3.4 for 2'- and 3'-hydroxyflavanone, respectively. The enantiomers of 4'-hydroxyflavanone could be effectively separated with S-beta-CD at a concentration of 2.0% (w/v) within 20 min. The enantioselectivity and enantioresolution follow the order 2'-hydroxyflavanone>>3'-hydroxyflavanone>4'-hydroxyflavanone. Alternatively, with the addition of sodium dodecyl sulfate (SDS) monomers at low concentrations in the electrophoretic system, enantioselectivity of these hydroxyflavanone aglycones could be enhanced with dual CD systems. In this case, SDS monomer acted as a complexing agent probably first with S-beta-CD and then subsequently with the analytes for increasing the effective electrophoretic mobility of the analytes towards the anode and as a selectivity controller for affecting the selectivity of hydroxyflavanones. Better enantioseparation between 2'-hydroxyflavanone and 3'-hydroxyflavanone could be achieved with a dual CD system consisting of S-beta-CD and gamma-CD than that with S-beta-CD and beta-CD. In addition, possible chiral recognition mechanisms of hydroxyflavanones are discussed.
研究了在低pH值下，使用随机硫酸化的β-环糊精（S-β-CD）或由S-β-CD和中性环糊精组成的双环糊精（CD）体系，在毛细管区带电泳（CZE）中对三种羟基黄酮苷元（包括2'-、3'-和4'-羟基黄酮）的手性分离。结果表明，S-β-CD是2'-羟基黄酮对映体分离的优良手性选择剂，是3'-羟基黄酮的良好手性选择剂。根据S-β-CD浓度在2.0%至0.75%（w/v）范围内，2'-和3'-羟基黄酮的对映体分辨率分别为10.5 - 19.5和1.8 - 3.4。4'-羟基黄酮的对映体在20分钟内可被2.0%（w/v）浓度的S-β-CD有效分离。对映选择性和对映体分辨率遵循2'-羟基黄酮>>3'-羟基黄酮>4'-羟基黄酮的顺序。另外，在电泳体系中加入低浓度的十二烷基硫酸钠（SDS）单体，双环糊精体系可增强这些羟基黄酮苷元的对映选择性。在这种情况下，SDS单体可能首先作为络合剂与S-β-CD结合，然后与分析物结合，以增加分析物向阳极的有效电泳迁移率，并作为选择性控制器影响羟基黄酮的选择性。与由S-β-CD和β-CD组成的双环糊精体系相比，由S-β-CD和γ-CD组成的双环糊精体系能实现2'-羟基黄酮和3'-羟基黄酮之间更好的对映体分离。此外，还讨论了羟基黄酮可能的手性识别机制。
