Antitumor Action of Amygdalin on Human Breast Cancer Cells by Selective Sensitization to Oxidative Stress

The treatment of MCF-7 and T47D human breast cancer cell lines with amygdalin was able to reduce the growth of both cells, in concentration and time-dependent manners. The potency of this inhibition against MCF-7 and T47D cells produced IC50 values of 39 and 45 mM, respectively. To investigate the correlation of this inhibition with oxidative stress, an amygdalin treatment of both cell lines was capable of inducing the generation of malondialdehyde (MDA) and oxidized glutathione levels. Also, this treatment caused the decrease of total glutathione and glutathione reductase activity. The proportional survival of tumor cells from this inhibition was positively correlated with the total glutathione, but it was inversely correlated with amygdalin or MDA levels (P < 0.001). In MCF-7 cells, the production of total glutathione was six times higher in the untreated than in amygdalin-treated cells, whereas this difference was reduced to 2.1 times in the T47D cells. Similarly, the production of MDA in MCF-7 cells was 2.4 times higher in the amygdalin-treated than in the untreated cultures, which were lowered to 1.3 times in the T47D cells. These data support a mechanism of amygdalin antitumor action against breast cancer cells based on the induction of oxidative stress.