The cells were divided into blank control group and different concentrations of PD treatment groups.The cell viabilities of undifferentiated 3T3-L1 adipocytes and differentiated mature adipocytes after treated 0－100 μmol·L^－1 with PD were determined by CCK-8 method.After the 3T3-L1 preadipocytes were treated with different concentrations （0， 5， 25，and 50 μmol·L^－1） of PD， DAPI staining was used to observe the morphology of apoptosis. Flow cytometry was used to detect the apoptotic rates and the percentages of 3T3-L1 preadipocytes in different cell cyeles. The protein expression levels of phosphatidylinositol 3-kinase （PI3K），phosphorylated phosphatidylinositol 3-kinase （p-PI3K），protein kinase B （AKT）， phosphorylated protein kinase B （p-AKT）， B-cell lymphoma-2 （Bcl-2），Bcl-2 associated X protein （Bax） and cleaved-Caspase 3 in each group were detected by Western blotting method， and the ratios of p-PI3K/ PI3K and p-AKT/AKT were calculated.

The CCK-8 results showed that compared with blank control group， the cell viabilities of 3T3-L1 preadipocytes in treatment groups were decreased （P<0.05 or P<0.01）， but the cell activity of mature adipocytes had no significant differences（P>0.05）. The DAPI staining results showed that compared with blank control group， the contour of 3T3-L1 preadipocytes in different concentrations of PD treatment became irregular and nuclear fragmentation was observed；the apoptotic bodies and chromatin fragments were observed.The results of flow cytometry showed that compared blank control group，the apoptotic rates of 3T3-L1 preadipocytes in different concentrations of PD treatment groups（P<0.01）， and the percentages of cells in S phase were increased （P<0.05 or P<0.01）.The Western blotting results showed that compared with blank control group， the expression levels of Bax and cleaved-Caspase 3 in different concentrations of PD treatment groups were increased （P<0.05 or P<0.01），and the expression levels of Bcl-2 were decreased （P<0.05 or P<0.01）；the ratios of p-PI3K/PI3K and p-Akt/Akt were decreased （P<0.05 or P<0.01）.

PD can significantly induce the apoptosis of 3T3-L1 preadipocytes， and its mechanism may be related to its influence in the expression levels of apoptosis-related proteins.