Objective To evaluate the effect of betanin on the ultrastructural changes of mitochondria and nuclei of the human cervical carcinoma HeLa cells, human hepatoma HepG2 cells and human lung adenocarcinoma A549 cells.

Methods The experiment was performed on three cell lines cultured for 36 h after exposing to betanin at a dose of 0, 62.5 and 500 ppm respectively. The effect of betanin on the mitochondria, nuclear and other parts of the cells was observed under the field of magnified 8 000-30 000 times electron microscope, and the number and cross-sectional area of mitochondria were calculated.

Results The normal HeLa, HepG2 and A549 cells showed typical nuclear characteristics of the tumor cells, with the swelling and cristae membrane disappearance of the mitochondria. Compared with betanin(0 ppm) group, the mitochondria number of the HeLa, HepG2 and A549 cells were increased by 10.9%, 25.0% and 12.6% respectively, and the cross-sectional area of mitochondria were reduced by 38.9%、70.1% and 65.3% respectively in betanin(62.5 ppm) group; the mitochondria numbers of the HeLa, HepG2 and A549 cells were increased by 15.2%, 79.7% and 40.0% respectively, while the cross-sectional areas of mitochondria were reduced by 67.8%, 77.6% and 81.9% respectively in betanin(500 ppm) group, moreover, the cristae membrane of the mitochondria was tended to intact. When betanin was added up to 500 ppm, all cells showed a necrotic phenomenon with the nuclear division, condensation and dissolution. After adding the betanin, the apoptotic bodies were found in Hela and A549 cells; and the autophagy appeared in HepG2 and A549 cells.

Conclusion Betanin could promote the recovery of the mitochondria morphology and structure of the tumor cells, and induce the nuclear necrosis and cell death.