Abstract: Acetylated epigallocatechin gallate (EGCG) was chemically synthesized in ethyl acetate solvent system for improving the lipid solubility and bioavailability of EGCG. The effects of acetyl anhydride dosage, catalyst pyridine dosage, ethyl acetate dosage, reaction temperature and reaction time on the substitution degree of acetylated EGCG were studied. As a result, it was found that 0.04 mL of acetic anhydride, 0.02 mL of pyridine, 20–60 mL of ethyl acetate, a reaction temperature of 20–25 ℃ and a reaction time of 1–3 h were optimal for the synthesis of acetylated EGCG with a degree of substitution in the range from 1 to 3 from 0.19 g of EGCG. The optimal synthesis conditions for EGCG acetylation that provided a substitution degree between 4 and 6 were 0.12–0.20 mL of acetic anhydride, 0.06–0.20 mL of pyridine, 10–20 mL of ethyl acetate, a reaction temperature of 17–25 ℃, and a reaction duration of 5–9 h, while those for a substitution degree of 7–8 were 0.40–0.80 mL of acetic anhydride, 0.01–0.20 mL of pyridine, 5–10 mL of ethyl acetate, a reaction temperature of 25–40 ℃, and a reaction duration of 5–9 h.

Key words: epigallocatechin gallate (EGCG), acetylation, substitution degree, molecular modification, bioavailability