Polymethoxyflavonoids from Vitex rotundifolia inhibit proliferation by inducing apoptosis in human myeloid leukemia cells

Three polymethoxyflavonoids from the fruit of Vitex rotundifolia, namely 2' ,3',5-trihydroxy-3,6,7-trimethoxyflavone (Vx-1), vitexicarpin (Vx-5) and ar temetin (Vx-6), were tested for their antiproliferative activity in human m yeloid leukemia HL-60 cells. They showed a dose-dependent decrease in the g rowth of HL-60 cells. The concentrations required for 50% inhibition of the growth (IC50) after 96 h were 4.03 mu m, 0.12 mu m and 30.98 mu m for Vx-1 , Vx-5 and Vx-6, respectively. Treatment of HL-60 cells with the flavonoids induced morphological changes that are characteristic of apoptosis. We jud ged the induction of apoptosis by the detection of DNA fragmentation in aga rose gel electrophoresis and the degree of apoptosis was quantified by a do uble-antibody sandwich ELISA and by flow cytometric analysis. The C-3 hydro xyl and C-8 methoxyl groups were found not to be essential for the activity , but the C-3' methoxyl instead of hydroxyl group lowered the antiprolifera tive, and apoptosis inducing activity. These results suggest that the polym ethoxyflavonoids isolated from V. rotundifolia may he used as potential che mopreventive and chemotherapeutic agents. (C) 2000 Elsevier Science Ltd. Al l rights reserved.