Effects of luteolin on the inhibition of proliferation and induction of apoptosis in human myeloid leukaemia cells.

Luteolin, a flavonoid isolated from the fruit of Vitex rotundifolia, has been examined with regard to the inhibition of proliferation and induction of apoptosis in human myeloid leukaemia HL-60 cells. The concentration required for 50% inhibition of the growth after 96 h was 15 +/- 1.1 microM. The mode of cell death induced by luteolin was found to be apoptosis, as judged by the morphologic alteration of the cells and by the detection of DNA fragmentation using agarose gel electrophoresis. The degree of apoptosis was quantified by a sandwich enzyme immunoassay and flow cytometric analysis. These results suggest that luteolin may be used as potential chemopreventive and chemotherapeutic agents.

Rotundifuran, a labdane type diterpene from Vitex rotundifolia, induces apoptosis in human myeloid leukaemia cells.

The inhibitory effect of rotundifuran, a labdane type diterpene isolated from the fruit of Vitex rotundifolia, on the proliferation of human myeloid leukaemia HL-60 cells was examined. The concentration required for 50% inhibition of the growth after 96 h was 22.5 microM. The mode of cell death induced by rotundifuran was found to be apoptosis, which was judged by the morphological alteration of the cells and by the detection of DNA fragmentation using agarose gel electrophoresis. The degree of apoptosis was quantified by a sandwich enzyme immunoassay and flow cytometric analysis. These results suggest that rotundifuran may be used as a potential chemopreventive and chemotherapeutic agent.

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 artemetin (Vx-6), were tested for their antiproliferative activity in human myeloid leukemia HL-60 cells. They showed a dose-dependent decrease in the growth of HL-60 cells. The concentrations required for 50% inhibition of the growth (IC50) after 96 h were 4.03 microM, 0.12 microM and 30.98 microM 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 judged the induction of apoptosis by the detection of DNA fragmentation in agarose gel electrophoresis and the degree of apoptosis was quantified by a double-antibody sandwich ELISA and by flow cytometric analysis. The C-3 hydroxyl 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 antiproliferative and apoptosis inducing activity. These results suggest that the polymethoxyflavonoids isolated from V. rotundifolia may be used as potential chemopreventive and chemotherapeutic agents.

Lavandulylflavonoids: a new class of in vitro apoptogenic agents from Sophora flavescens.

The root of Sophora flavescens has been reported to possess antitumor activity in Sarcoma 180, lymphoid leukemia 1210 and melanotic melanoma. We have isolated four cytotoxic flavonoids with a lavandulyl side-chain at C8 and tested for their effects on human myeloid leukemia HL-60 cells and human hepatocarcinoma HepG2 cells, in terms of inhibition of proliferation and induction of apoptosis. They showed potent antiproliferative effects with IC(50) values from 11.3 microM to 18.5 microM in HL60 cells and from 13.3 microM to 36. 2 microM in HepG2 cells. Treatment of HL-60 cells with the lavandulylflavonoids induced apoptosis in a dose-dependent manner. Apoptosis was judged by the detection of DNA fragmentation by agarose gel electrophoresis and the degree of apoptosis was quantified by a sandwich enzyme immunoassay. The hydration of C4"'C5"' double bond with or without C3 hydroxylation caused a complete loss of cytotoxicity. These results suggest that the lavandulyl side-chain is essential for the activity of the flavonoids isolated from S. flavescens which may be used as cancer chemotherapeutic and chemopreventive agents.

Induction of apoptosis by a novel intestinal metabolite of ginseng saponin via cytochrome c-mediated activation of caspase-3 protease.

Ginseng saponins exert various important pharmacological effects with regard to the control of many diseases including cancer. The novel intestinal bacterial metabolites of ginseng protopanaxadiol saponins have recently been found and isolated after the oral administration of ginseng extract in human and rats. 20-O-(beta-D-Glucopyranosyl)-20(S)-protopanaxadiol (IH-901) formed from ginsenosides Rb1, Rb2, and Rc is of particular interest in cancer chemoprevention and treatment. We investigated the effects of IH-901 on the human myeloid leukemia cell line HL-60 in terms of inhibition of proliferation and induction of apoptosis. IH-901 showed a significant cytotoxic activity in HL-60 cells (IC(50) = 24. 3 microM) following a 96-hr incubation. Treatment of HL-60 cells with IH-901 resulted in the formation of internucleosomal DNA fragments. The dose- and time-dependent induction of apoptosis by IH-901 was demonstrated in sandwich enzyme immunoassay and the results were confirmed by flow cytometric analysis. Morphological examination of IH-901-treated samples showed cells with chromatin condensation, cell shrinkage, and nuclear fragmentation, all typical characteristics of apoptotic cells. The treatment of HL-60 cells with IH-901 caused activation of caspase-3 protease and subsequent proteolytic cleavage of poly(ADP-ribose) polymerase. IH-901 did not affect the expression of antiapoptotic protein Bcl-2 but did cause a release of mitochondrial cytochrome c into cytosol. In conclusion, our results demonstrate that IH-901 dramatically suppresses HL-60 cell growth by inducing programed cell death through activation of caspase-3 protease, which occurs via mitochondrial cytochrome c release independently of Bcl-2 modulation. These results may provide a pivotal mechanism for the use of IH-901 in the prevention and treatment of leukemia.

Cytotoxic lavandulyl flavanones from Sophora flavescens.

Two new lavandulylated flavanones, (2S)-2'-methoxykurarinone (1) and (-)-kurarinone (2), were isolated from the root of Sophora flavescens, together with two known lavandulyl flavanones, sophoraflavanone G (3) and leachianone A (4), and two known isoflavonoids, formononetin and l-maakiain. The structures of 1 and 2 were determined on the basis of optical rotation and spectral evidence and by comparison with known compounds. Compounds 1-4 exhibited cytotoxic activity against human myeloid leukemia HL-60 cells.

5-Arylamino-2-methyl-4,7-dioxobenzothiazoles as inhibitors of cyclin-dependent kinase 4 and cytotoxic agents.

5-Arylamino-2-methyl-4,7-dioxobenzothiazoles were synthesized as inhibitors of cyclin-dependent kinase 4 (CDK4) and cytotoxic agents. Most of the 4,7-dioxobenzothiazoles exhibited selective inhibitory activities for the CDK4 and cytotoxic potential against human cancer cell lines.