Large‐scale preparation of five polar polyphenols including three isomers from Phyllanthus emblica Linn. by preparative high‐speed counter‐current chromatography

The separation of polar compounds is challenging work due to poor retention and insufficient selectivity. In the present study, an efficient strategy for large‐scale preparation of five polar polyphenols including three isomers from Phyllanthus emblica Linn has been established by preparative high‐speed counter‐current chromatography. Macroporous resin column chromatography was used for the enrichment of the polar polyphenols. However, sugar and other ultra‐polar impurities were co‐washed out with the targets. Liquid‐liquid extraction with ethyl acetate/water (1/1, v/v) solvent system was developed to remove the ultra‐polar impurities with a clearance rate of 95%. Finally, the targets were introduced to preparative high‐speed counter‐current chromatography for separation using ethyl acetate/n‐butanol/acetic acid/water (2/7/1/10, v/v/v/v) solvent system. As a result, 191 mg of Mucic acid 1,4‐lactone 5‐O‐gallate, 370 mg of β‐Glucogallin, 301 mg of Gallic acid, 195 mg of Mucic acid 1,4‐lactone 3‐O‐gallate and 176 mg of Mucic acid 1,4‐lactone 2‐O‐gallate with purity higher than 98% were obtained from 1.5 g of sample. Mucic acid 1,4‐lactone 3‐O‐gallate, Mucic acid 1,4‐lactone 3‐O‐gallate, and Mucic acid 1,4‐lactone 2‐O‐gallate are isomers. The results showed that high‐speed counter‐current chromatography could be well developed for the separation of polar compounds from natural products.