Red American ginseng: ginsenoside constituents and antiproliferative activities of heat-processed Panax quinquefolius roots

Abstract

Red Asian ginseng ( Panax ginseng C. A. Meyer, Araliaceae) is used in many Oriental countries. In this study, the saponin constituents and anticancer activities of steamed American ginseng ( Panax quinquefolius L.) roots were evaluated. The contents of 12 ginsenosides in the roots were determined using high performance liquid chromatography (HPLC). After the steaming treatment (100 - 120 degrees C for 1 h and 120 degrees C for 0.5 - 4 h), the quantity of 7 ginsenosides decreased and that of 5 others increased. The content of ginsenoside Rg3, a previously recognized anticancer compound, increased significantly when the root was steamed at 120 degrees C for 0.5 - 3 h. The antiproliferative effects of unsteamed and steamed (120 degrees C for 1 h and 2 h) American ginseng root extracts were assayed by the modified trichrome stain (MTS) method using three cancer cell lines (SW-480, HT-29, NSCLC). Heat-processing increased the antiproliferative effect of American ginseng significantly, and the activity of the extract from roots steamed for 2 h was greater than that of roots steamed for 1 h. Chemical constituents and antiproliferative activities of white and red Asian ginseng have also been evaluated. Five representative ginsenosides, Rb1, Rd, Re, Rg2 and Rg3, were studied. Ginsenoside Rg3 had the most potent effect. The antiproliferative activities of red American ginseng are augmented when ginsenoside Rg3 is increased.

Fig. 1

Chemical structures of the assayed ginsenosides.

Fig. 2

HPLC analysis of ginsenosides in unsteamed and steamed American ginseng roots. Chromatograms of unsteamed (A), or steamed at 120 °C for 2 h (B) and 4 h (C) are shown. Ginsenoside peaks: (1) Rg1, (2) Re, (3) Rh1, (4) Rg2, (5) 20R-Rg2, (6) Rb1, (7) Rc, (8) Rb2, (9) Rb3, (10) Rd, (11) Rg3, (12) Rh2. Peak numbers are not shown if the saponins were not detected.

Fig. 3

Antiproliferative effects of Asian ginseng root extract on HT-29 cells. Cancer cells were exposed to white ginseng and red ginseng extract (0.1, 0.25, 0.5, 1 mg/mL) for 72 h and cell proliferation was determined by the MTS assay. The results are expressed as the mean ± SD of three independent experiments. * p < 0.05, red ginseng vs. white ginseng.

Fig. 4

Antiproliferative effects of unsteamed and steamed (120 °C for 1 h or 2 h) American ginseng root extract on cancer cells determined by the MTS assay. Four doses (0.1, 0.25, 0.5 and 1 mg/mL) were used and the treatment time for SW-480 (A) and HT-29 (B) cells was 72 h; for NSCLC cells (C), it was 48 h. The results are expressed as the mean ± SD of three independent experiments.

Fig. 5

Antiproliferative effects of ginsenosides on SW-480 cells. Cancer cells were exposed to ginsenosides (30, 100, and 300 μM) for 72 h and cell proliferation was determined by the MTS assay. At the concentration of 300 μM, the antiproliferative effects of Rg3 were 99.0 ± 1.3%, respectively. The results are expressed as the mean ± SD of three independent experiments. * p < 0.05; ** p < 0.01 vs. control.