Background and purpose: Recently

a large number of researches have shown that cruciferous plants have the chemopreventive effect on tumor. Mechanisms of antitumorigenesis were investigated on antioxidation

antimutation

immunity and inducing apoptosis

and so on. Mustard seeds (MS) are the seeds belong to the cruciferous plants. This study aimed to investigate antioxidation and immune deviation of MS on colorectal tumor in rats induced by 1

2-dimethylhydrazine (DMH). Methods: A total of 48 male Wistar rats were randomly divided into four groups: DMH alone

DMH+5%MS

DMH+7.5%MS

and the untreated control group(Saline). Colorectal tumorigenesis was induced by intraperitoneal injecting 30 mg/kg DMH once a week for 20 weeks. At the end of 32 weeks

the rats were sacrificed

then colorectal tumor incidence was observed and histological type was determined by HE staining. A colorimetric assay was used to detect levels of the lipid peroxidation product malondialdehyde (MDA) and the activity of antioxidant enzymes in the serum of all rats. The levels of Th1 and Th2 cytokines were detected with Luminex200. Results: No tumorous lesion was found in the untreated control group. However

the total tumor incidence in DMH+5%MS group and DMH+7.5%MS group was significantly decreased 33.3% and 58.3% respectively

compared with the DMH group’s (100%

P0.05). As DMH induced colorectal tumorigenesis

MDA and Th2 cytokines in the serum were significantly higher in the DMH group than those in the untreated control group (P0.05)

but the activities of antioxidant enzymes were significantly lower (P0.05). While the MS treatment

compared with the DMH group

significantly suppressed the MDA level but enhanced the activities of antioxidant enzymes and levels of Th1 cytokines (P0.05). Conclusion: MS significantly decrease prevalence rates of DMH-induced colorectal tumor in rats. The mechanism may be related with the antioxidation and immune balance deviation.