**2. Ginsenosides: structure, pharmacokinetics and mechanism**

Ginsenosides are specific types of triterpene saponin, a broad group of chemical compounds. Ginsenosides are found nearly exclusively in Panax species (ginseng) and up to now more than 150 naturally occurring ginsenosides have been isolated from different organs of ginseng [12]. Ginsenosides appear to be responsible for most of the activities of ginseng including anti-diabetic, anti-allergic, anticarcinogenic, anti-inflammatory, anti-atherosclerotic, antihypertensive, and immunomodulatory effects as well as anti-stress activity and effects on the central nervous system [6]. The structures of ginsenosides Rb1 and Rg1 are shown in **Figure 1**.

#### **2.1 Structure of ginsenosides**

Shi *et al*. [13] have reported that the seven major ginsenosides (Rg1, Re, Rb1, Rc, Rb2, Rb3 and Rd) were present in various parts of Chinese ginseng of various ages. Ginsenoside content is higher in the leaf and root hair but lower in the stem than that in other parts of the plant and that the total content of ginsenosides in the leaf decreases with age [1, 13]. Ginsenosides are divided into three main categories, the 20(S)-protopanaxadiol, 20(S)-proto- panaxatriol and oleanane families according

**Figure 1.** *Structures of ginsenosides Rb1 and Rg1. (Adapted from [5]).*

to the number and position of sugar moieties on the sterol chemical structure. it is difficult to clarify the influence of the sugar moiety at different positions on pharmacological actions [14].
