Simultaneous preparation of naturally abundant and rare catechins by tannase-mediated biotransformation combining high speed counter current chromatography

•Simultaneous preparation of naturally rare EGC and EC.•Separation of the four catechins by HSCCC under normal and reversed phase modes.•Cooperative employment of tannase biotransformation and HSCCC separation. Simultaneous preparation of naturally rare catechins, EGC and EC, has been realized by tannase-mediated biotransformation combining high speed counter current chromatography. In addition, simultaneous preparation of the four catechins, EGCG, ECG, EGC, and EC in green tea extract has also been achieved by HSCCC under the normal phase and the reversed phase modes. The identity of the catechins was determined by HPLC-DAD-ESI-MS and quantification of the catechins was performed by HPLC-DAD. In a typical HSCCC separation, 27.2mg 98.8% EGCG, 14.1mg 94.7% EGC, and 9.3mg 97.5% EC were obtained. This new method is efficient, time-saving and valuable for biological studies.