Growth inhibition and differential induction of human leukemic U937 cells by Chinese medicinal herbs

Abstract

Effects of boiling-water extracts and 80% (v/v) ethanol extracts from Chinese medicinal herbs on the antiproliferation and differentiation of human leukemic U937 cells were examined. Conditioned medium from peripheral blood monocytes (MNC-CM) stimulated with various levels (200-800 μg/mL) and types of herb extracts (MNC-CM mode) were used to screen the effective herbs. Results showed that among the herbs tested, MNC-CM from boiling-water extracts of Huang Gi (HG), Gan Cao (GC), Lian Zi (LZ), Da Zao (DZ), and Tang Shen (TS) showed remarkable (> 40%) growth inhibition on the U937 cells at high dosage, whereas mixtures of boiling-water extracts of tested herbs with culturing medium displayed insignificant results. Meanwhile, inferior inhibition on cell proliferation was observed when U937 cells were treated with ethanol extracts with MNC-CM or conventional mode. Assays for cytoplasmic superoxide production (NBT reducing ability) by U937 cells induced by ethanol precipitates of boiling-water extracts (100-400 μg/mL) from LZ indicated a dose-dependent positive percentage (31-49%), revealing the apparent differentiation-inducing effect of MNC-CM on U937 cells.