TLC separation of methylated (–)-epigallocatechin-3-gallate

Abstract

Methylated EGCG was separated from the crude extract using Sephadex LH-20 column chromatography with methanol as the mobile phase, and a semi-preparative HPLC method with water-dimethylformamide-methanol-acetic acid (157:40:2:1, v/v/v/v) as the mobile phase. The chemical structure of the separated catechin was confirmed by ESI-MS in the negative-ion mode. Three different mobile phases were used for silica gel and reversed phase TLC of EGCG and methylated EGCG. R_fvalues of both catechins were calculated and are reported. In the normal phase, the best condition of separation was with chloroform-methanol-water (65:35:10; v/v/v; lower phase) being used as the mobile phase. On octadodecylsilanised silica gel plates, the phase water-acetonitrile-methanol-acetic acid (79.5:18:2:0.5; v/v/v/v) offered the best separation of catechins.