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Ginseng: Chemical Identification

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Ginseng and Ginsenosides
50647-08-0

CHEMICAL IDENTIFICATION

CAS Registry No.: 50647-08-0
Chemical Abstracts Service Names:Prosapogenin (Ginseng) (9CI)
Synonyms:Ginseng, ginseng root extract, ginseng root neutral saponins, ginseng root tincture, ginsengwurzel extract, panax, panax ginseng, panax schinseng, prosapogenin
Botanical Names: The Panax genus contains about six species native to eastern Asia and two native to eastern North America (Foster, 1996a,b). Panax ginseng C.A. Meyer (Asian, Chinese, Korean, or Oriental ginseng) and Panax quinquefolius L. (American ginseng) are most commonly used in nutraceuticals.

Description:

Ginseng is a perennial aromatic herb with a short underground stem (rhizome) associated with a fleshy white root. Its root system consists of the primary root and its branches and of some adventitious roots developed from the rhizome. The above-ground part of the plant is a 30-70 cm single stem that dies annually (Sticher, 1998). The plant blooms after two years, reaches maturity after five and is harvested in its sixth year (Hook, 1979). True ginsengs are members of the genus Panax in the Araliaceae family. In addition to Panax ginseng and Panax quinquefolius, other ginsengs include Panax japonicus (Japanese ginseng), Panax notoginseng (Sanqui or Tienqi ginseng), Panax elegantior (Pearl ginseng), Panax pseudoginseng (Himalayan ginseng), and Panax zingiberensis (ginger ginseng) (Ocollura, 1997).

Some plants are not a true ginseng (i.e., different genus or family), but they have the term ginseng in their common names. These include Siberian ginseng (Eleutherococcus senticosus) which is widely used in dietary supplement preparations, Prince ginseng (Pseudostellaria heterphylla), Indian ginseng (Ashwangdha), and Brazilian ginseng (Pfaffia paniculata) (Ocollura, 1997). Except where it is impossible to distinguish the form of ginseng, these products are not discussed further.

Technical Products and Impurities:

Despite the growing market for extracts and powders, the most popular ginseng products remain the white and red roots. Ginseng roots may be graded by size. For example, Heaven 15 is a grade of Korean ginseng which means 15 roots fit into a standard ginseng container. Heaven 30 means 30 roots fit into the same container. The larger the number, the smaller and less valuable the root (Ocollura, 1997). Table 1 lists various ginseng products and their availability.

Ginseng is an expensive crop to produce so adulteration or substitution with cheaper products occurs (Ocollura, 1997). Some products sold as ginseng have contained Mandragora officinarum, with hyoscine, Rauwolfia serpentina, with reserpine, and Cola, with caffeine; other commercial preparations were found to be adulterated with phenylbutazone and aminopyrine (Chandler, 1988). To protect its interests in the Hong Kong market, the Ginseng Board of Wisconsin organized a labeling system for genuine American ginseng products (Proctor, 1996). A comprehensive ginseng evaluation program of hundreds of commercial ginseng products was initiated by the American Botanical Council to determine if adulteration has occurred; in June 1998, the American Botanical Council confirmed that the results will not be available for another year (Proctor, 1996; Ocollura, 1997; American Botanical Council, 1998).

Chemical Composition:

Several classes of compounds have been isolated from ginseng root. These include triterpene saponins, essential oil-containing polyacetylenes and sesquiterpenes, polysaccharides, peptidoglycans, nitrogen-containing compounds, and various ubiquitous compounds such as fatty acids, carbohydrates, and phenolic compounds (Sticher, 1998).

The chemical constituents of ginseng believed to contribute to its pharmacological effects are triterpene saponins. These compounds are named ginsenosides Rx according to their mobility on thin-layer chromatography plates, with polarity decreasing from index "a" to "h". This property is a function of the number of monosaccharide residues in the sugar chain. The aglycons are protopanaxadiol and protopanaxatriol; both have a dammarane skeleton. So far, 31 ginsenosides have been isolated from the roots of white and red ginseng. They can be categorized into three groups depending on their aglycons: protopanaxadiol-type ginsenosides, protopanaxatriol-type ginsenosides, and oleanolic acid-type saponins (Sticher, 1998).

Nearly all dammarane ginsenosides isolated from white ginseng root are derivatives of 20S protopanaxadiol and 20S protopanaxatriol (see table on page 6). Almost all the ginsenosides isolated from white ginseng are also found in red ginseng; however, some ginsenosides (20R Rg2.; 20R Rh1 ; Rh2, Rs1, Rs2, Q-R1, and NG-R1) are characteristic saponins for red ginseng.

The 20R compounds are degradation products formed by heating and hydrolysis during steaming (Sticher, 1998).

 The structures of the more common ginsenosides are shown below.

20(S)-protopanaxadiols

Ginsenoside

R1

R 2

R3

Rb1

glc-glc

H

glc-glc

Rb2

glc-glc

H

glc-ara(p)

Rc

glc-glc

H

glc-ara(f)

Rd

glc-glc

H

glc

20(S)-protopanaxatriols
Ginsenoside R1 R2 R3
Re H -O-glc-rha glc
Rf H -O-glc-glc H
Rg1 H -O-glc glc
Rg2 H -O-glc-rha H
Rh1 H -O-glc H
glc = glucose; ara(p) = arabinose in pyranose form; ara(f) = arabanose in furanose form; rha = rhamnose

Sources: Gillis, 1997; Sticher, 1998

Panax ginseng, Panax quinquefolium, and Panax notoginseng are closely related chemically and taxonomically. Generally, they contain total ginseng saponin below 0.1 percent, and the sapogenins constitute chiefly dammarane-type triterpenes, with a higher content of panaxadiol and panaxatriol, but a very low content of oleanolic acid as sapogenin. Panax notoginseng contains no oleanolic acid sapogenin. The total saponin content of the remaining Panax species is 10-20 percent, and oleanolic acid is the major sapogenin (Peigen, 1989).

The stems, leaves, flowers, flower-buds, and fruits contain more ginseng saponins than the ginseng root. The underground part contains higher amounts of ginsenosides Rb1, Rc, and Rg1, while the above-ground parts contain higher amounts of ginsenosides Rd, Re, and Rg1 (Peigen, 1989).

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Web page last updated on August 15, 2005