Abstract: The objective of this study was to investigate the protective effect of tannins from Sanguisorba officinalis on myelosuppression in mice.The myelosuppression model was induced by peritoneal injection of cyclophosphamide (CTX).Then the myelosuppression mice were randomly divided into:model group,colony-stimulating factor group,three ziyuglycoside-I treatment groups (5,2.5,0.5 mg/kg),three ziyuglycoside-II treatment groups (5,2.5,0.5 mg/kg),three Burnet prosapogenins treatment groups (5,2.5,0.5 mg/kg) and normal group.The drugs were chronically administrated to myelosuppression mice once a day for 7 days.The counts of peripheral blood leukocytes,DNA contents and CD34+ expression of bone marrow cells and the O6-methyl guanine-DNA methyltransferase (MGMT) protein expression were used as main indexes and were determined.The results showed that  S.officinalis significantly increased peripheral WBC (P<0.05);significantly elevated bone marrow DNA content (P<0.05);significantly promoted the expression of CD34+ (P<0.05);also significantly promoted MGMT protein expression (P<0.05).Based on these results,it was concluded that S.officinalis can significantly antagonize CTX-induced myelosuppression in mice.

Key words: Sanguisorba officinalis, cyclophosphamide, myelosuppression, Paul marrow effect