CYCLODEXTRINS AND THEIR DERIVATIVES IN THE RESOLUTION OF CHIRAL NATURAL PRODUCTS: A REVIEW

Many natural compounds of biological and pharmacological interest are asymmetric and show optical activities; for example, optical isomers of ephedrine produce different amphetamine-like stimulus effects, and (S)-(-)-alpha-ionone (woody-like taste) and (R)-(-)-alpha-ionone (violet taste) possess different olfactory properties, etc. Consequently, the need for enantiomerically pure natural compounds is a growing concern for active research in pharmacology, biochemistry, and the quality control of chiral natural compounds. Different kinds of chiral selectors including crown ether, macrocyclic antibiotics, cellulose, and cyclodextrins (CDs) have been investigated to resolve optical natural products. Among them, cyclodextrins and their derivatives are the most frequently employed chiral selectors and are used as stationary phase or additives in the separation of natural products for their powerful ability in chiral resolution and the various available products in the market. This review first summarizes the utility of CDs and their derivatives as stationary or additives in the chiral resolution of natural products, typically flavanones, alkaloids, lignans, coumarins, terpenoids, amino acids, peptides, etc. In addition, analytical techniques of gas chromatography (GC), high-performance liquid chromatography (HPLC), capillary electrophoresis (CE), and capillary zone electrophoresis (CZE) applied in separation of optical natural products using CDs or their derivatives as chiral selectors are also summarized.