*2.2. Mouse Leydig Cells Proliferation Activity of Ten Fractions*

The proliferation activity of these 10 fractions was assessed using the MTT assay in TM3. All the 10 fractions were found to possess the proliferation activity (Figure 4).

**Figure 4.** Effects of the ten fractions on TM3 (a *p* < 0.01, b *p* < 0.05).

#### *2.3. Screening of Active Compounds by Using Partial Least Squares*

The selected initial data was further processed by PLS in order to establish a model for predicting the potential active components in *L. meyenii*. Parameters were set as follows: Confidence level was 95%, R2 = (0.0, 0.794), Q2 = (0.0, –0.285), and the parameters showed that the established PLS model was effective. We could use the PLS to carry on the weights analysis about the impact of the common peeks area exported from ten HPLC spectra of 10 fractions (x-axis) to the proliferative activity of TM3 (y-axis) and screening of major compounds which influenced bioactivity.

In our data set, the weights plot summarized the variables both to explain X and to correlate to Y. The results were shown in (Figure 5). The weights greater than one indicated important variables, and three potential biological markers of *N*-benzyl-hexadecanamide (**9**), *N*-benzyl-(9z,12z)-octadecadienamide (**6**) and *N*-benzyl-(9z,12z,15z)-octadecatrienamide (**2**) had high contributions to the proliferation activity of TM3. Meanwhile, they were considered to be potential active compounds for further study [19].

**Figure 5.** Model effect weights of the ten compounds on TM3.
