Growth inhibitory effects of crude pomegranate peel extract on chronic myeloid leukemia, K562 cells

Pomegranate (Punica granatum) is currently a member of Lythraceae family which has potentially cytotoxic activities. Numerous studies have been done on cytotoxic components of pomegranate's juices, barks and leaves. The peels, which considered as a waste, contain higher antioxidant components compared with other parts of the plant.

To investigate the potential anti-cancer activity of pomegranate peel on growth and cell death mechanisms of chronic myeloid leukemic (CML) cells, K562.

Punica granatum peels extract (PGPE) was extracted by successive ethanol extraction, 80% (v/v), freeze dried, diluted to 20 mg/mL working concentration and was subjected to phytochemical screening. K562 cell was treated with crude PGPE for 72 h. Following IC50 concentration, the apoptosis, cell cycle and protein analysis were evaluated. Cell growth inhibition assay was performed by conventional trypan blue exclusion assay. Apoptosis and cell cycle were analyzed by flow-cytometry using BD apoptosis and cell cycle kits and protein analysis by western blotting. All the results are expressed as mean ± standard error of mean of three independent experiments. Statistical analysis was performed by nonparametric Mann-Whitney U-test.

Results demonstrated that PGPE promotes growth inhibition of K562 cells mainly via G2/M phase arrest while still conserving apoptosis induction, but at a lower rate. Apoptosis activities were proposed by the up-regulation of caspases and cytochrome c with an elevated level of p21 and p53.

PGPE caused an inhibition in cell proliferation of CML cell mainly by cell cycle arrest.