Dear Sayeda,

Extraction: -

A crude extract using a two-step extraction procedure, tea leaves was first brewed in water at 50◦C for 10 minutes. The extracted leaf was then separated and re-extracted with water at 80◦C for 10 minutes. The infusion from each step was finally freeze-dried for 24 hours to obtain the tea extract in powder form. The extract from the first step was rich in EGC and the extract of the second step was rich in EGCG .The purity of catechins obtained from this method was lower however, this method uses water for the extraction process rather than potentially harmful organic solvents like ethyl acetate, methanol.

Purification:-

Isolation of individual Epigallocatechin (enzymes) from their mixture was a challenge because their structures and molecular weights were very similar. Countercurrent chromatography and column chromatography have been used to isolate individual catechins from their mixtures. Countercurrent chromatography has been done using two different solvent mixtures flowing in opposite directions, and column chromatography includes a number of solid support phases that include silica gel, alumina, and Sephadex. Based on the different affinities of the individual catechins for the column material, they were separated by differentially eluting the catechins with various solvents.