Two-step chromatographic procedure for the preparative separation and purification of epigallocatechin gallate from green tea extracts

The preparative separation and purification of epigallocatechin gallate (EGCG) from green tea extracts was achieved by a two-step chromatographic procedure. In the first step, a preparative β-cyclodextrin (β-CD) bonded silica chromatography operated in the polar organic mode using methanol/acetonitrile/acetic acid as the mobile phase was applied. Due to a high selectivity for EGCG over epicatechin (EC) and caffeine (CA), an efficient separation of EGCG from EC and CA was achieved and the system could be scaled-up with high recovery of EGCG (>90%). The EGCG-rich fraction obtained from the first step was subjected to the second step where a preparative C-18 chromatography operated in the reversed-phase mode using water/methanol/acetic acid as the mobile phase was applied. The resolution of EGCG was significantly enhanced as the sample contained no EC and CA. The system could also be scaled-up and both the purity and recovery of EGCG reached about 90%. In summary, the chromatographic procedure consisting of two such complementary steps gave a satisfactory purification results: the purity and recovery of EGCG were >90% and >80%, respectively. Most significantly, the purification method could be more easily scaled-up, showing good potential for industrial applications.

► A two-step chromatographic procedure was used to purify EGCG from green tea extracts. ► The first step using polar-organic phase β-CD bonded silica provided a high selectivity for EGCG over EC and CA. ► The second step using reversed-phase C-18 provided a high resolution for EGCG over EGC and ECG. ► EGCG was obtained at a purity of >90% with a overall recovery of >80%. ► The purification method could be more easily scaled-up.