Here, our results showed that the DNA ladders of MCF-7, MDA-MB-468, MDA-MB-231 and L929 cells treated with Fraction CE were observed within seven days. In contrast, fragmented DNA was not observed in MCF-12A cells. Therefore, DNA ladder formation indicated that the cytotoxic effect of Fraction CE caused inhibition in the growth of breast cancer and normal fibroblast cells through apoptosis. Fraction CE also inhibited growth in normal breast cells, but not to the point of death through apoptosis. In the L929 cells, Fraction CE inhibited cell growth within six days and induced cell death on Day 7 after incubation. Although treated L929 cells showed DNA ladders at Day 7, the incubation time was longer and the dose was higher than in the breast cancer cell lines. Thus, our Fraction CE seemed to be safe for normal cells. However, further experiments are needed to evaluate the specific molecules in the apoptotic pathway. Our previous study showed that P. nigrum extract exhibited a cytotoxic effect and induced DNA fragmentation on a breast cancer cell line [19]. In addition, other studies have found that an ethanolic extract of Mimosa caesalpiniifolia leaves and an aqueous extract of Plinia edulis leaves caused cytotoxicity and induced cell death and DNA fragmentation in MCF-7 cells, via a mechanism that seemed to use the apoptosis pathway [36,37].
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