A CALLUNA-VULGARIS EXTRACT 5-LIPOXYGENASE INHIBITOR SHOWS POTENT ANTIPROLIFERATIVE EFFECTS ON HUMAN LEUKEMIA HL-60 CELLS

A water-Calluna vulgaris extract (water-CVE) was found to be a relatively specific arachidonate 5-lipoxygenase inhibitor and showed potent anti-proliferative effects on human leukemic HL60 cells. Water-CVE completely inhibited potato 5-lipoxygenase activity at 250-mu-g/ml, partially inhibited soybean 15-lipoxygenase at pH 7.4 and had no effect either on this 15-lipoxygenase at its optimal activity pH (pH9) or on Lupinus albus 5-, 8-, 15-lipoxygenase. In culture, the proliferation and DNA synthesis of HL60 cells were decreased by water-CVE in a dose-dependent manner with an IC50 of 200-mu-g/ml at day 4. This effect of water-CVE is related to the starting density of HL60 cells. These results suggest that arachidonate 5-lipoxygenase metabolites and/or leukotrienes could play an essential role in cellular functions of leukemic cells and may explain the success of the use of Calluna vulgaris as tea and baths in folk medicine.