Objective To explore the possible mechanism of Anchang Decoction treating ulcerative colitis（ UC）adopting the method of metabolism. Methods Seventy-six Wistar rats were randomized into the blank group（ n =4）

the model group（ n = 12）

the Lizhu Changle（ 丽珠肠乐） group（ n = 12）

the mesalazine group

the low

medium and high dose Anchang Decoction groups（ n = 12 in each group）. Rats in other groups were given anal injection of 2 4 6-three nitrobenzene sulfonic acid solution（ 90 mg / kg） to establish UC rat models except the blank group.Rats in the blank group and the model group were given normal saline 3 ml by gavage. The Lizhu Changle group was given Lizhu Changle solution 50 million viable organism / ml by gavage

0. 12 ml each time. The mesalazine group was given mesalazine suspension 5 mg / ml by gavage

0. 35 ml each time. The low

medium and high dose Anchang Decoction groups were respectively given Anchang Decoction concentrate 1

5 and 10 ml /（ kg· d） by gavage. Rats in each group were given 3 ml of liquid medicine and normal saline by gavage

once every day. For 15 days. On the 5 th

10 th and 15 th day

rats’ colonic mucosa tissues were examined by the method of metabolism which adopted gas chromatography / mass spectrometry（ GC-MS） technology. The data collected were made multivariate statistical analysis

including principal component analysis（ PCA）

ciscriminant analysis by partial least squares（ PLS-DA） and orthogonal partial least squares discriminant analysis（ OPLS-DA）. T-test combined with VIP value of OPLS-DA model first principal component were adopted to find the differentially expressed metabolites and to analyze its relative amount and the metabolic pathway. Results The obtained chromatogram map and the mass spectra database were made matching identification. At last

48 accurately characterized compounds were got. After multivariate statistical analysis

score plot showed that the difference of colonic tissue metabolic phenotype of rats in the model group and the blank group was significant. Sample points showed complete separation. The most significant difference was on the 10 th day. Compared with the Lizhu Changle group and the mesalazine group

the difference between the Anchang Decoction groups and the blank group was not significant. The difference in the medium dose Anchang Decoction group was less significant than in the low and high dose Anchang Decoction groups. After analysis

11 potential metabolic markers were found at last

which were uridine

ethylamine sulfonic acid

glycocoll

threonine

lactic acid

β-alanine

methyl glycosine

seminose

xylopyranose

glucose and kestose. Compared with the model group

11 metabolin in the Anchang Decoction groups all showed expression callback（ P < 0. 05）. The callback range in the medium dose Anchang Decoction group was the best. Conclusion The regulating effect of Anchang Decoction on 11 metabolin might be the pathway and mechanism to treat UC.