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Combination of capillary electrophoresis and molecular modeling to study the enantiomer affinity pattern between β‐blockers and anionic cyclodextrin derivatives in a methanolic and water background electrolyte
Author(s) -
Guo Jialiang,
Wang Jincai,
Lin Hang,
Feng Ying,
Shen Huanqi,
Huang Ruoshi,
Liu Lian,
Zhao Zhixiong
Publication year - 2019
Publication title -
journal of separation science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.72
H-Index - 102
eISSN - 1615-9314
pISSN - 1615-9306
DOI - 10.1002/jssc.201800884
Subject(s) - capillary electrophoresis , chemistry , enantiomer , cyclodextrin , acebutolol , affinity electrophoresis , aqueous solution , electrolyte , chromatography , organic chemistry , affinity chromatography , enzyme , medicine , electrode , blood pressure , radiology
In order to have deep insights into the mechanisms of enantiomer affinity pattern in both aqueous and non‐aqueous systems, an approach combining capillary electrophoresis and molecular modeling was undertaken. A chiral β ‐blocker; acebutolol, was enantioseparated in aqueous capillary electrophoresis and non‐aqueous capillary electrophoresis using two anionic β ‐cyclodextrin derivatives. The enantiomer affinity pattern of acebutolol was found to be opposite when an aqueous background electrolyte was replaced with non‐aqueous background electrolyte in the presence of heptakis(2,3‐di‐O‐acetyl‐6‐sulfo)‐ β ‐cyclodextrin but remained the same in the presence of heptakis(2,3‐di‐O‐methyl‐6‐sulfo)‐ β ‐cyclodextrin. Molecular docking of acebutolol into two β ‐cyclodextrin derivatives indicated two distinct binding modes called ‘up’ and ‘down’ conformations. After structure optimization by molecular dynamics and energy minimization, both enantiomers of acebutolol were preferred to the ‘up’ conformation with heptakis(2,3‐di‐O‐methyl‐6‐sulfo)‐ β ‐cyclodextrin while ‘down’ conformation with heptakis(2,3‐di‐O‐acetyl‐6‐sulfo)‐ β ‐cyclodextrin. The further calculation of the complex energy with solvent effect indicated that heptakis(2,3‐di‐O‐acetyl‐6‐sulfo)‐ β ‐cyclodextrin had higher affinity to S ‐acebutolol than R ‐acebutolol in non‐aqueous capillary electrophoresis while it showed better binding to R ‐acebutolol in aqueous capillary electrophoresis. However, the heptakis(2,3‐di‐O‐methyl‐6‐sulfo)‐ β ‐cyclodextrin bound better to R ‐acebutolol in both aqueous and non‐aqueous capillary electrophoresis, implying that the binding mode played more important role in chiral separation of heptakis(2,3‐di‐O‐methyl‐6‐sulfo)‐ β ‐cyclodextrin while the solvent effect had prevailing impact on heptakis(2,3‐di‐O‐acetyl‐6‐sulfo)‐ β ‐cyclodextrin.