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Maytenus is the largest genus of the family Celastraceae and the species Maytenus ilicifolia (popularly known as 'Espinheira Santa'). It is widely used in traditional Brazilian medicine to treat stomach conditions including nausea, gastritis, and ulcers. In this study, the apoptotic effects of a spray-dried extract of M. ilicifolia (SDEMI) was evaluated using human hepatocellular cells (HepG2), colorectal carcinoma cells (HT-29), and normal keratinocytes (HaCaT). Cells were treated with SDEMI for 4 and 24 h, then were assayed for levels of apoptosis, caspase-3, and Bcl-2 by flow cytometry, immunostaining, and Western blot, respectively. Significant differences between groups were determined using analysis of variance (P < 0.05). For HepG2 and HT-29 cells treated with SDEMI, various cytotoxic effects were observed compared with control cells at all timepoints assayed (P < 0.001). Furthermore, positive caspase-3 staining and down-regulation of Bcl-2 were observed, consistent with the induction of cell death detected in these cell lines. In contrast, treatment of HaCaT cells with SDEMI was associated with a protective effect compared with control cells at both timepoints (P < 0.001). For example, increased expression of Bcl-2 and negative caspase-3 staining were detected. Taken together, these results suggest that SDEMI protects normal cells, while SDEMI mediates induction of apoptosis via down-regulation of Bcl-2 and involvement of caspase-3 in human carcinoma cells.

The ability to induce apoptosis is an important marker for cytotoxic antitumor agents. Some natural compounds have been shown to modulate apoptosis pathways that are frequently blocked in human cancers, and therefore, these compounds provide novel opportunities for cancer drug development. Phyllanthus, a plant genus of the family Euphorbiaceae, exhibits multiple pharmacological actions. Of these, Phyllanthus niruri extracts exhibit significant antitumor activity, which is consistent with the traditional medicinal use of this plant. To examine the apoptotic effects of a spray-dried extract of P. niruri (SDEPN), human hepatocellular carcinoma cells (HepG2, Huh-7), colorectal carcinoma cells (Ht29) and keratinocytes (HaCaT) were exposed to the extract for 4, 8 and 24 h. Flow cytometry and caspase-3 immunostaining were used to detect apoptosis, while analysis of variance was applied to identify significant differences between groups (P < 0.05). At all timepoints, the SDEPN induced significantly different cytotoxic effects for HepG2 and Huh-7 cells compared with control cells (P < 0.001). In contrast, the SDEPN had a protective effect on HaCaT cells compared with control cells at all timepoints (P < 0.001). In caspase-3 assays, activation was detected after cell death was induced in Huh-7 and HepG2 cancer cells by the SDEPN. In combination, these results indicate that the SDEPN is selectively toxic towards cancer cell lines, yet is protective towards normal cells.