**2. A Tour d'Horizon of the Ginsenosides chemical diversity**

Initially, the term "ginsenosides" was used to design a series of tetracyclic triterpenoid saponins from *P. ginseng*. According to different aglycones, triterpenoid saponins may be classified into tetracyclic triterpene saponins (e.g., dammaranetype saponins, DAMS) and pentacyclic triterpene saponins (e.g., oleanolic-type (OT) and ocotillol-type (OA) saponins). The main aglycones of which are protopanaxadiol (PPD), protopanaxatriol (PPT), oleanolic acid, and ocotillol [1, 11]. A variety of saponins are biosynthesized with different types of glycosides groups and/or linkage orders. DAMS, such as PPTs and PPDs, generally contain 1 to 4 glycosyl groups linked with the aglycone structure. Sugar chains are usually linked to the C3 or C4 position of the aglycone in PPD type saponins, whereas regularly linked to the C6 or C20 position in PPT type saponins.

The ginsenoside chemical annotation is 'Rx', where 'R'stands for root and 'x' stands for chromatographic polarity in alphabetical order. To date, the Rb (protopanaxadiols) and the Rg groups (protopanaxatriols) are the most studied ones (**Figure 1**). With the availability of commercial standards, these ginsenosides Rb1, Rb2, Rc, and Rd from the Rb group (or PPD), and the ginsenosides Rg1, Rg2, Re, and Rf from the Rg group (or PPT) (**Figure 1**) were more readily analyzed during the extraction procedure, thus leading in greater available information on their biological activity.

Panax plant phytochemistry has been investigated since the mid-nineteenth century, mostly with *P. ginseng* or *P. quinquefolius* as starting materials. Samuel S. Garrigues isolated the first ginsenoside, "panaquilon," from *P. quinquefolius* roots in 1854 [19]. Due to the renewed interest in natural compounds and traditional medicines, various unique *Panax* species, such as *P. vietnamensis* Ha et Grushv. and *P. sokpayensis*, have piqued the interest of many phytochemists since 1970s [20, 21]. Between 1970 and 2000, owing to the development and democratization in laboratory techniques such as two-dimensional nuclear magnetic resonance (2D NMR) or quadrupole time of flight mass spectrometry (Q-TOF-MS) that were employed to detect *Panax* chemical components and clarify stereo configurations, it was found that the structures of many saponin compounds mostly belonged to C17 side-chain that varied for both PPD- and PPT-type ginsenosides [22–26]. But since the 2000s, an impressive and growing number of new saponins have been

#### **Figure 1.**

*Chemical structure of Panax species' common protopanaxadiol (PPD or Rb) and protopanaxatriol (PPT or Rg) ginsenosides.*

discovered owing to the significant advances in chromatography, spectroscopy and mass spectrometry methods that allow rapid and efficient screening of natural *Panax* products. The work of Yao et al. [27] perfectly illustrated this impressive progress by resolving 945 ginsenosides from the leaves of *P. notoginseng* by using two-dimensional liquid chromatography (2D-LC) separation technology, based on high-performance liquid chromatography coupled with high-resolution mass spectrometry (HPLC-HRMS) platform, 662 of which were novel.

From this brief historical background, it is indisputable that the emergence of more efficient analytical approaches has substantially improved our understanding of the chemical variety of ginsenosides. Here are some additional important observations on the chemical diversity to be taken into account for future development (beginning with the most well-known compounds):


*How Do Extraction Methods and Biotechnology Influence Our Understanding and Usages… DOI: http://dx.doi.org/10.5772/intechopen.103863*
