Separation of epigallocatechin gallate and epicatechin gallate from tea polyphenols by macroporous resin and crystallization

Epigallocatechin gallate (EGCG) and epicatechin gallate (ECG) are the most abundant ester catechins of green tea polyphenols (GTPs) with numerous potential bioactivities, which have wide application prospects in the fields of medicine and functional foods. In this study, a new method using macroporous resin and crystallization was established to separate and purify EGCG and ECG. Two resins with high adsorption and desorption capacities for EGCG and ECG were screened through static adsorption/desorption tests, and the LX-20B resin was selected through column chromatography due to its best separation effect. Moreover, the column separation parameters of LX-20B resin (sample amount, ethanol elution concentration, elution volume, and elution flow rate) were optimized. After resin purification, the EGCG and ECG purity were 70.08 +/- 2.55% and 74.97 +/- 2.66%, respectively, and the recovery rates were 68.07 +/- 2.43% and 74.28 +/- 2.24%, respectively. After crystallization, the EGCG purity reached 95.87 +/- 0.89%, with a total recovery rate of 58.66%, and the ECG purity reached 95.55 +/- 1.30%, with a total recovery rate of 62.45%. The separation efficiency of the resin showed no significant change after 6 cycles. These results show the proposed method to be a simple, eco-friendly, and cost-effective separation method for the industrial separation and purification of EGCG and ECG from GTPs.

Automated summary

A new method using resin and crystallization was developed to separate and purify EGCG and ECG from green tea polyphenols. After resin purification and crystallization, high purities of EGCG and ECG were achieved, with stable separation efficiency of the resin over multiple cycles.