Suppressive effects of ginsenosides on U937 cells stimulated with TNF-α. (A) Nine ginsenosides were standardized to concentrations in the PGSE at 3 mg/ml according to Table 1. U937 cells were treated with ginsenosides for 24 hours following with 20 units/ml TNF-α stimulation for 2 hours, and the transcription of CXCL-10 was measured by quantitative RT-PCR as described in Methods. (B) Ginsenosides including Rb1, Rb2, Rc, Rd, Re, Rf, Rg1, Rg3 and Rh1 were pooled together to investigate the combinatorial effect of the nine ginsenosides on CXCL-10 transcription following TNF-α stimulation by using quantitative RT-PCR. (C) Comparable inhibitory effects of the ginseng extract (PGSE) and the mixture of individual ginsenosides on CXCL-10 transcription. U937 cells were treated with 3 mg/ml of PGSE or the mixture of GS (that is equivalent to 3 mg/ml of PGSE) for 24 hours following with 20 units/ml of TNF-α stimulation for another 2 hours. The transcription of CXCL-10 was measured by quantitative RT-PCR as described in Methods. Values represent the average ± SD of three independent experiments and statistically analyzed by two tailed, paired t-test. ψ: p < 0.005; †: p < 0.01; *: p < 0.05. GS, ginsenosides; PGSE, 70% ethanol-water extracts of ginseng.