Isolation and antioxidative activity of EGCG from green tea leftovers

The EGCG were extracted with 95% ethanol under ultrasound.The ethanol extract were concentrated and separated and purified by polyamide resin column chromatography to obtain EGCG monomer, and these EGCG were tracked and inspected with TLC and HPLC.The EGCG purity was more than 97% and yield reached 12%.The antioxidative activity of EGCG in vitro for scavenging l, 1-dipheny-2-picryhydrazyl free radical ( DPPH·) and O-2·was studied using ultraviolet-visible spectrophotometry.It was shown the EGCG had stronger ability than that of VC for elimination free radicals.The activities for scavenging DPPH·and O-2·were tea polyphenols > EGCG > VC, and the corresponding IC50 ( half of suppression rate) values were 12 and 5.9μg/mL, respectively.The above results suggest that EGCG is one kind of good natural oxidation inhibitor.