## 3 Results and Discussion
### Discrimination of PJ, PM, and PZ by a Multivariate Statistical Analysis  
The variations in the 16 major compounds among the three ginseng species were intuitively represented by a two-way hierarchical clustering analysis heat map. As shown in the heat map in Figure 5E, PZ could be clearly distinguished from PJ and PM by a hierarchical clustering analysis. In contrast, PJ and PZ were not well-discriminated, and their ginseng contents were much closer than that of PZ. Figure 5: The percentage contents of the 16 ginensosides **(A,** PJ; **B,** PM; **C,** PZ) and total ginensosides (**D**) in the three ginseng herbs; The content difference of 16 saponins by a two-way hierarchical clustering analysis heat map **(E)**. Ginensoside (G)-Rg1, G-Re, G-Rb1, G-Rc, G-Rb2, G-Rb3, G-Rf, G-Rd, G-Rg2, G-Rg3, G-F3, G-Rh1, G-Ro. Notoginsenoside (N)-R1 and chikusetsu saponin (CS) -IV and CS-Iva. In order to further reveal differences in the chemical composition among PJ, PM, and PZ, PLS-DA and OPLS-DA were also utilized to distinguish between different ginseng species. A total of 50 ginseng samples (20 batches of PJ; 20 batches of PM; 10 batches of PZ) were analyzed. Among them, 35 samples were randomly selected as the training set, and 15 were the prediction set. The result is shown in Figure 6. The established PLS-DA model showed good fitness (R2X = 0.699, R2Y = 0.897) and predictability (Q2 = 0.85). The PLS-DA score plot displayed that the three clusters representing the PJ, PM, and PZ groups were well-segregated, thereby indicating the remarkable differences of ginensoides among these three _Panax_ herbs. A chance permutation test suggested that the model was not over-fitted (as shown in Figure 6A-3). All samples in the prediction set are correctly identified, so the PLS-DA model has a classification accuracy of 100%. The VIP (variable importance in the projection) plot was used to find the important compounds. When the VIP cutoff was set at 1.0, nine important compounds for discriminating between PJ, PM, and PZ were discovered. G-Rf, G-F3, and CS-IV have the highest contribution that can distinguish the above three herbs (as shown in Figure 6A-4). The result of the OPLS-DA analysis based on pairwise comparison methods is shown in Figure 6B-D. The figure reveals that samples from the same species were tightly clustered together and that different species groups were discriminated from one another by the OPLS-DA score plot. Among those with a VIP value exceeding 1.0, seven important compounds for the discrimination between PJ and PM (in order of CS-IV, G-Rf, G-F3, G-Rd, G-Ro, G-Rb1, and G-Rg1), nine for PM and PZ (in order of G-Rh1, N-R1, G-F3, G-Rb1, CS-IVa, G-Rg1, G-Re, G-Rg3, and G-Rf), and nine for PJ and PZ (in order of G-Rh1, N-R1, G-Rg2, G-F3, G-Rg3, G-Rg1, G-Rb1, G-Re, and CS-IV) were obtained. In Chinese folk medicine, PJ and PM are historically and generally used as a herbal medicine for similar indications. These two herbs possess combined medicinal effects, which are _P. ginseng_'s \"conserving vitality\" activities and _P. notoginsnets_'s \"replenishing blood\" activities [10]. However, PJ and PM are considered to be two different herbal medicines, and are recorded as \"zhujieshen\" and \"zhuzishen\" in the Chinese Pharmacopoeia, respectively. Thus, investigation on the difference in their chemical constituents and biopharmaceutical effects is necessary and crucial. In our qualitative and quantitative analyses based on an LC-MS technique, PLS-DA and OPLS-DA clearly distinguished between the two herbs, even though they are very similar in composition. Furthermore, the average content of total ginensoides in PJ was conspicuously higher than that in PM, even though PM's content in PPDs and PPTs was more abundant. These chemical differences may contribute to the differences in clinical application.