Induction of Apoptosis in Human Leukemic Cell Lines U937, K562 and HL-60 by Litchi chinensis Leaf Extract Via Activation of Mitochondria Mediated Caspase Cascades

The apoptogenic activity of Litchi chinensis leaf extract (LCLE) was investigated against three human leukemic cell lines-U937, K562 and HL-60. LCLE inhibited cell growth and metabolic activity of the leukemic cells and showed characteristic features of apoptosis. Flow cytometric analysis showed appreciable number of cells in early and late apoptotic stages. While U937 and K562 cell populations were arrested in the G2-M phase, the HL-60 cell population was arrested in the G1 phase of cell cycle. LCLE induced apoptosis is mediated through mitochondrial intrinsic pathway involving the release of cytochrome c into the cytosol and activation of caspase-9 and caspase-3.