Abstract: To explore the inhibitory effect of Paeonia ostii seed oil on transplanted H22 tumor in mice and its mechanism.H22 tumor bearing mouse models were established by transplanting H22 tumor into normal mice.48 mice were randomly divided into normal control,model,positive control,and low,medium,and high-dose P.ostii seed oil groups (at doses of 3.6,1.8,0.9 mL/kg,respectively) consisting of 8 mice each.Each mouse received intragastric administration for 10 consecutive days.The positive control group was administered intraperitoneally with 5-fluorouracil (5-FU) at doses of 20.0 mg/kg every day.After the last administration,all mice were sacrificed.The tumor growth inhibitory rate of low,medium and high-dose P.ostii  seed oil groups were 18.4%,26.9%,34.7% respectively with a good dose-effect relationship.Compared with model group,the low,medium,and high-dose groups increased spleen and thymus indices at different degrees,decreased aspartate transaminase (AST),alanine aminotransferase (ALT),alkaline phosphatase (ALP) while improved white blood cell (WBC);suppressed the activity of telomerase (TE) and the expression of B-cell lymphoma-2 (BCL-2) while raised the expression of Bcl-2 associated X protein (BAX) obviously.These results showed that high-dose P.ostii seed had significant anti-tumor effect on transplanted H22 tumor in mice and the possible mechanisms may be related to the regulation of immune function,inhibition of TE activity and up-regulating the expression of BAX and down-regulating the expression of BCL-2.

Key words: Paeonia ostii seed oil, H22 tumor-bearing mice, anti-tumor, mechanisms