Fig. 2

a Bivariate Annexin V and propidium iodide (PI) staining of THP-1cells treated with total plant extract (RTE) (63 μg/ml), saponin fraction extract (SE) (63 μg/ml), rutin (R) (25 and 125 μM), kaempferol (K) (29 and 40 μM), mixture of catechin, epicatechin, and epicatechin gallate (CEEG) (28 and 100 μM) for 48 h. The untreated cells, CTRL(−) and cells treated with camptothecin 2 μM as CTRL(+) are reported. The x-axis showed Annexin V-FITC-A (area) binding and the y-axis staining of PI labeled population (phycoerytrin PE emission signal detector). The lower left (LL) quadrant contains the viable (Annexin V- /PI-) population; the lower right (LR) quadrant contains the damaged (Annexin V+ /PI-) cells, early apoptotic cells; the upper right (UR) quadrant contains the late apoptotic cells (Annexin V+ /PI+); the upper left quadrant (UL) contains the necrotic cells and debris (Annexin V- /PI+). b Late apoptotic cell proportion (%). Data were presented as the mean ± standard deviation. Statistical analysis was performed using the unpaired Student’s t-test and data compared with the CTRL(−) cells (*: p < 0.05; **: p < 0.01; ***: p < 0.001) and CTRL(+) cells (°: p < 0.05; °°: p < 0.01; °°°: p < 0.001)