Abstract: 【Aim】 To ascertain the toxic effect of momordicin I and a new compound (charantin B) from ethanol extracts of Momordica charantia leaves on larval Ostrinina furnacalis hemocytes (Ofh), and to illuminate its action mechanism as well. 【Methods】 The inhibition effects of momordicin I, momordicin II, charantin B and azadirachtin A on Ofh cells were compared by using CCK-8 assay. The effects of momordicin I and charantin B on Ofh cell morphology structure were observed by using inverted phase contrast microscopy and fluorescence microscopy, and the induced necrosis effects on Ofh cells were studied by using trypan blue staining and flow cytometry (FCM) technologies. 【Results】 Momordicin I, momordicin II and charantin B had apparent inhibition effects on Ofh cell proliferation, with the IC₅₀ values of 7.566, 24.340 and 8.514 μg/mL, respectively, at 36 h after treatment. The cytotoxicity of momordicin I and charantin B were significantly higher than that of momordicin II and azadirachtin A. Using inverted phase contrast microscopy, we found that after exposure to momordicin I and charantin B, Ofh cell shapes changed to circular and swelling increased, and the cellular membrane bubbled, suggesting that both momordicin I and charantin B could destruct cell morphology structure. Further research indicated that the mortality rates of cells in the groups treated with 8 μg/mL momordicin I and charantin B were significantly higher than that of the control group at 12-48 h after treatment, and in a time-dependent manner, indicating that the cytotoxicity of momordicin I is significantly higher than that of charantin B. Fluorescence microscopy observation revealed that nuclear morphology was irregular, the cell membrane dissolved and the nucleus appeared to be severely damaged after AO/EB staining, and cells exhibited a non-uniform orange-yellow fluorescence after treatment with 8 μg/mL momordicin I and charantin B, showing a typical characteristic of necrosis. Flow cytometry analysis showed that Ofh cells treated with momordicin I and charantin B were dramatically induced to undergo necrosis, and the total cell necrosis rates were 74.92%±2.02% and 49.77%±1.69%, respectively, after 36 h treatment with 8 μg/mL momordicin I and charantin B. 【Conclusion】 Momordicin I and charantin B have significant inhibition effects on cell proliferation and can induce necrosis, which may account for the antifeedant effect of momordicins on O. furnacalis and the inhibition of growth and fecundity of O. furnacalis treated by momordicins.

Key words: Ostrinina furnacalis, hemocyte, momordicin, charantin B, Ofh cell, necrosis