## 3 Results  
### Effect of Herbal Extracts on LPS-Induced NO Production in RAW 264.7 Cells  
NO plays many important roles in the immune system. Specially, NO is produced in high amounts in macrophages to respond to stimulation. To investigate the anti-inflammatory effect of the 10 extracts, the inhibitory effect of the extracts 1-10 on NO production in LPS-activated RAW 264.7 macrophages was measured. In addition to evaluating their cytotoxicity in RAW 264.7 cells, cell viability was observed. At non-cytotoxic concentrations, 8 out of the 10 extracts caused a significant reduction in NO production in LPS-activated RAW 264.7 cells. These eight extracts included the herbal extracts _Lizhongtang_ and _M. officinalis_. Compared to those in the LPS-treated group (9.48 \(\pm\) 0.30 \(\upmu\)M), the NO levels in the co-culture with _Lizhong-tang_ (12.5, 25, 50, and 100 \(\upmu\)M) and LPS were significantly lower, at 7.81 \(\pm\) 0.26 \(\upmu\)M, 8.48 \(\pm\) 0.13 \(\upmu\)M, 7.59 \(\pm\) 0.13 \(\upmu\)M, and 2.70 \(\pm\) 0.10 \(\upmu\)M, respectively (Figure 2). Similarly, _M. officinalis_ (50 \(\upmu\)M and 100 \(\upmu\)M) extracts significantly reduced the NO levels to 6.59 \(\pm\) 0.10 \(\upmu\)M and 1.15 \(\pm\) 0.10 \(\upmu\)M, respectively, as compared to those in the LPS-treated group (9.48 \(\pm\) 0.30 \(\upmu\)M). These results suggest that _Lizhong-tang_ and _M. officinalis_ may have anti-inflammatory activities in LPS-activated RAW 264.7 cells. Considering the cell viability results after treatment with _Lizhong-tang_ and _Mofficinalis_, it was observed that the inhibitory effect on NO levels in LPS-activated RAW 264.7 cells was not due to cytotoxicity. Evaluation of the Inhibitory Activity of the Active Compounds of Lizhong-Tang on LPS-Induced NO Production in RAW 264.7 Cells  
To determine the NO-inhibitory effects of the active compounds of _Lizhong-tang_, NO assays were carried out post-treatment of RAW 264.7 cells with the six compounds from _Lizhong-tang_, including liquiritin, ginseng Rb1, ginseng Rg1, glycerrhizin, and 6-gingerol. Liquiritin, ginseng Rg1, glycerrhizin, and the NO levels in the LPS-stimulated RAW 264.7 cells. Of these compounds, liquiritin and 6-gingerol were the most effective at non-cytotoxic concentrations. No cytotoxicity was observed at all the tested concentrations of liquiritin (12.5, 25, 50, and 100 \(\upmu\)M), similar to that in the untreated group. In the group stimulated with 100 ng/mL LPS, the NO levels were 21.52 \(\pm\) 0.42 \(\upmu\)g/mL, while in the experimental group treated with 12.5 \(\upmu\)M liquiritin, the NO levels decreased compared to those in the group stimulated with LPS to 20.19 \(\pm\) 0.34 \(\upmu\)g/mL; this decrease, however, was not significant. In the group treated with 25 \(\upmu\)M, 50 \(\upmu\)M, and 100 \(\upmu\)M liquiritin, NO levels were 19.33 \(\pm\) 0.27 \(\upmu\)g/mL, 14.33 \(\pm\) 0.13 \(\upmu\)g/mL, and 7.19 \(\pm\) 0.14 \(\upmu\)g/mL, respectively, which represented an inhibition (\(p\) < 0.001) of the NO levels in the LPS-stimulated group (Figure 3). For ginseng Rb1, no cytotoxicity was observed at the 12.5, 25, 50, and 100 \(\upmu\)M, concentrations similar to that seen in the untreated group. In the group stimulated with 100 ng/mL LPS, the NO levels were 21.52 \(\pm\) 0.42 \(\upmu\)g/mL, while that in the experimental groups treated with 12.5, 25, 50, and 100 \(\upmu\)M ginseng Rb1 were 21.48 \(\pm\) 0.05 \(\upmu\)g/mL, 21.57 \(\pm\) 0.25 \(\upmu\)g/mL, 21.24 \(\pm\) 0.17 \(\upmu\)g/mL, and 22.33 \(\pm\) 0.05 \(\upmu\)g/mL, respectively (Figure 3). Thus, no significant change was observed in the NO levels, after treatment with Rb1 at any of the concentrations tested. No cytotoxicity was observed at all concentrations of ginseng Rg1 (12.5, 25, 50, and 100 \(\upmu\)M), similar to that seen in the untreated group.