Chiral separation of catechin and epicatechin by reversed phase high-performance liquid chromatography with , ?-cyclodextrin stepwise and linear gradient elution modes

Catechin and epicatechin were enantioseparated by high-performance liquid chromatography (HPLC) with a phenyl column and aqueous mobile phases containing 0.05% (w/v) and 0.6% (w/v) of ,B-cyclodextrin for catechin and epicatechin, respectively. ,B-Cyclodextrin was found to be scarcely retained on a phenyl column. Consequently, it was suggested that catechin, which was eluted earlier than epicatechin, formed more stable inclusion complex with ,B-cyclodextrin than epicatechin and earlier eluted enantiomers, (-)-catechin and ( + )-epicatechin, formed more stable diastereomer complexes with ,B-cyclodextrin than the respective enantiomers. This was confirmed by ,B-cyclodextrin-modified micellar electrokinetic chromatography and Benesi -Hildebrand plots by fluorescence spectrophotometry. Effect of sugars (D-sucrose, D-glucose, and D-fructose) on the epimerization of ( + )-catechin and ( + )-epicatechin by heating was investigated by HPLC with a ,B-cyclodextrin stepwise elution mode, in which two kinds of aqueous eluents containing different concentrations of ,B-cyclodextrin were used by turns. The epimerization of the two enantiomers was suppressed only when D-fructose was added. Separation of ten kinds of catechins including catechin and epicatechin enantiomers was investigated by a ,B-cyclodextrin linear gradient HPLC elution mode without using organic solvents, where two kinds of aqueous eluents containing different concentrations of ,B-cyclodextrin were used with changing their ratio gradually. These catechins in a green tea infusion could be separated successfully by this method.(C) 2022 Elsevier B.V. All rights reserved.

Automated summary

Catechin and epicatechin were separated by HPLC using a phenyl column and aqueous mobile phases containing β-cyclodextrin. The interaction between the compounds and β-cyclodextrin was confirmed, and the effect of fructose on the epimerization of the enantiomers was investigated. Additionally, a successful separation of catechins in green tea infusion was achieved using a gradient HPLC elution mode with β-cyclodextrin.