Abstract: In order to study the regulative and preventive effects of tea polyphenol on intestinal flora imbalance of mice caused by antibiotics,ZnCl₂ precipitation,ethyl acetate extraction method was used to extract tea polyphenols,high performance liquid chromatography (HPLC) method was used to detect extraction results;BALB/c mice were randomly divided into 4 groups:normal control group,imbalanced model group,preventive group and treatment group,regularly to keep feces.The independently improved method was adopted to extract faecal total bacterial genome DNA and PCR-DGGE technique was used to obtain the intestinal flora molecular fingerprint.Similarity analysis,diversity analysis and sequence analysis of the different bands were then carried out.The results demonstrated that the content of epigallocatechin gallate (EGCG) as an active ingredient in extract of tea polyphenols was 42.67%;The improved lysozyme method can effectively extract faecal bacteria total DNA and ensure the downstream analysis technology to carry out smoothly;In the DGGE analysis,bands in treatment group,preventive group and control group had small degrees of difference (P<0.05).All above results indicated that tea polyphenol had certain adjustment and preventive effects on intestinal flora imbalance caused by antibiotics and the preventive effect was proved to be better than the adjustment effect.

Key words: tea polyphenols, EGCG, HPLC, PCR-DGGE, intestinal flora