Panax ginseng: More Than an Adaptogen Remedy

Ginseng is considered one of the oldest remedies for improving human health. Its uses and "magical" effects in China have been known for 5000 years (Nag et al., 2012). Ginseng includes numerous plant species belonging to the Panax species, such as Panax ginseng C.A. Meyer and Panax quinquefolius, L. P. ginseng, the most popular, can be found in the vast territory between China, Russia, Korea, and Mongolia. Its botanical name expresses its beneficial properties; in fact, ginseng derives from the Chinese words (jen shen) that mean human-like form, while panax (Latin word for panacea) means "cures all diseases" (Anonymous, 2009). Several active components are present in the Panax genus, including ginsenosides, polysaccharides (Ru et al., 2015), and polyacetylenes (Knispel et al., 2013). Ginsenosides are the major components possessing biological activities with differences regarding their aglycone moieties, as showed in Fig. 3.20.1. There are several ginseng products on the market, with Korean red ginseng (KRG) undoubtedly the most popular. KRG is obtained by steaming, using conventional methods, while white ginseng is obtained by drying the fresh plant. KRG produces new constituents, not present in white ginseng, such as Rg3, Rg5, and RK1 (Kim et al., 2007; Fig. 3.20.1). When ginseng is eaten, the ginsenosides present undergo a chemical transformation, which limits their bioavailability. In the gut, Rb1 is transformed into compound K, by intestinal microbiota, operating progressive deglycosylation (Wang et al., 2011). This chemical modification is an important process aimed to increase the bioavailability of ginsenoside metabolites and to enhance their biological effects (Qian et al., 2006). In fact, compound K, but not Rb1, possesses chemopreventive effects (Wang et al., 2012; Yang Hsu et al., 2013). However, the bioavailability of ginsenoside metabolites is limited, because of extensive biliary excretion (Liu et al., 2009) or efflux processes regulated by P-glycoprotein (Xie et al., 2005). Even diet, influencing the intestinal microbiota, causes changes in the levels of ginsenoside metabolites (Wan et al., 2017).