Abstract: We observed cytotoxicity, apoptosis, the expression of Fas protein, growth state and recovery of damaged cells produced by botanical insecticide piperine on C6/36 cell strain of Aedes albopictus using MTT, Annexin-V/PI double staining and inverted microscope observation. The results indicated that piperine caused the morphological change in the treated cells at the concentration of above 0.035 mmol/L. The cells showed pantomorphia under the inverted microscope. They became swollen or shrunk, and the space between cells was widened. A large number of cells assembled into conglobations, and then ablated, disaggregated and died. The IC₅₀ of C6/36 cell 24 hours after treatment by piperine was 0.32 mmol/L. Moreover, the cytotoxicity increased with the raising of concentration of piperine. The results of Annexin-V/PI double staining showed that the apoptosis was apparent in treatments of the piperine concentration above 0.28 mmol/L, while the rate of apoptosis was 19.4% in the treatement of the piperine concentration of 0.56 mmol/L. The expression of Fas protein increased in the treatments of  the piperine concentration above 0.28 mmol/L but not apparently, and the total death rate was 72.7%. Treated with high concentration of piperine (0.56 mmol/L) for 24 hours and 48 hours respectively, following a period of growth retardation, the cells of 24-hour-group could recover slowly while the 48-hour-group showed inconvertibility. The results suggest that there is time dependence of the effect on C6/36 by piperine. Apoptosis, however, is not the main mechanism. The cytotoxicity would be increased with the treating time prolonged.

Key words: Aedes albopictus, piperine, C6/36 cell line, apoptosis