An Analysis of Ginseng Root in Relation to Anatomy, Botany, Pharmacognosy, Macroscopy and Microscopy

Definition of Ginseng Root

According to the Ph Eur. monograph 1523, the definition of ginseng is a “Whole or cut dried root, designated white ginseng; treated with steam and then dried, designated red ginseng, of Panax ginseng C. and must contain at least a sum total of 0.4% ginsenosides Rg and Rb(1)

The United States Pharmacopoeia 32 distinguishes between American Ginseng and Asian Ginseng, where American Ginseng has a requirement only relating to total ginsenosides, as opposed to the Asian Ginseng requirement of ginsenosides Rg and Rb(1)(2).

It is noteworthy that dried substance is used in both definitions, the process by which the sample is to be adequately dried will be outlined further on in the report.

Asian Ginseng as Defined by the USP

• Asian Ginseng consists of the dried roots of Panax ginseng C.A. Meyer (Fam. Araliaceae). It contains not less than 0.2% of ginsenoside Rg1 and not less than 0.1% of ginsenoside Rb1, both calculated on the dried basis.(1)

American Ginseng as Defined by the USP

• American Ginseng consists of the dried roots of Panax quinquefolius L. (Fam. Araliaceae). It contains not less than 4.0 percent of total ginsenosides, calculated on the dried basis.(2)

Identifying a Suspected Sample as Being Containing Ginseng

The parameters which the British Pharmacopoeia 2008 uses for the assay of Ginseng are as follows

1. Foreign Matter(3) — Free from moulds/insects and other animal contamination(4)
2. Foreign matter:
3. Foreign organs from the plant which are not drug
4. Foreign elements from other sources, which can be of vegetable or other origin.(4)
5. Loss on drying (3) — Maximum of 10% loss on drying
6. Dry 1.000g of powdered drug by heating in an oven at 100–105 °C.
7. Total Ash
8. Incinerate 2.000–3.000g of drug in dish at temperature not exceeding 450 °C, until the sample is free from carbon.
9. Cool sample, weigh.
10. If no carbonless sample obtained, filter with hot water and collect residue on clean filter paper
11. Evaporate at temperature not exceeding 450°C
12. A sample containing ginseng should not contain more than 7% m/m ash (5)
13. Ash Insoluble in Hydrochloric Acid
14. Boil ash for 5 minutes with 25 mL 2 mol/L hydrochloric acid.
15. Collect insoluble matter in clean filter paper
16. Wash with hot water, ignite.
17. Calculate percentage mass in % w/w

From a microscopic point of view, a suspected ginseng sample is ruled as not being negative for presence of ginseng should there be the presence of the following as defined by the British Pharmacopeia.

The powder is pale yellow. Examine under a microscope using chloral hydrate solution R. The powder shows the following diagnostic characters (Figure 1523.-1): abundant fragments of parenchymatous cells with thin or slightly thickened walls, some of which contain cluster crystals of calcium oxalate; fragments of large secretory canals containing yellowish-brown resin in granular masses; non-lignified tracheids and partially lignified vessels with spiral or reticulate thickening, isolated; fragments of xylem (longitudinal section, transverse section) consisting of vessels and thin-walled parenchymatous cells; isolated cluster crystals of calcium oxalate; fragments of cork (surface view, transverse section) often associated with phelloderm having slightly thickened cells and with the outer layers of the cortical parenchyma.

TLC Analysis for the Presence of Ginsenosides in Ginseng Root

According to the British Pharmacopeia, the appropriate test for the qualitative analysis of ginsenosides Rb and Rg are as follows.

Preparation of the Sample to be Tested

1. Boil 1.0g of powdered sample under reflux for 15 minutes with 10 mL of 70% v/v methanol.
2. Filter after cooling
3. Dilute to 10.0 mL with methanol.

Preparation of the Mobile Phase:

A mobile phase of ethyl acetate, water, butanol 25:50:100 was used.

The mixture was allowed to seperate for 10 minutes.

The upper layer of this mixture is used.

Preparation of a Reference Solution

Reference solution used:

• Aescin — 5.0 mg
• Arbutin — 5.0 mg
• Methanol — 1.0 mL

Staining of the Resulting Plate

The resulting TLC plate is sprayed with anisaldehyde and heated at 105–110 °C for 5–10 min.

Determination of the Resulting Plate for Presence of Ginsenosides

British Pharmacopeia — Figure 1523.-2

Anatomical Features — Macroscopic

In appearance, the root of ginseng is similar to that of liquorice.

When the root is dried, the root is pale yellow in colour and wrinkled.

A white bark surrounds the entirety of the root. There are two to three portions connected to the upper part of the root. The root has at least one scar at its termini.

The “main root” is considerably thicker in diameter in comparison to the rhizome. The rhizome is the part of the root from which the bud stems. The main root is the most important portion of the plant for the extraction of ginsenosides, given its size.

From the main root, the fibre roots and the tail roots extend. These are small roots which have roles in anchorage and nutrition.

Anatomic Features — Microscopic

The cellular structures of the ginseng root are primarily the calcium oxalate, which are druses. The root of ginseng stores calcium oxalate for a variety of biosynthetic pathways.

In a Japanese study, Immunofluorescence and Immunoelectron Microscopic Localization of Medicinal Substance, Rb1, in Several Plant Parts of Panax ginseng by Sadaki Yokota et al. ginseng root was analysed under means of immunoelectron microscopy for the presence of ginsenoside Rb. In attached figures one and two the localization of Rb is illustrated in the cortical parenchymal cells and pith parenchymal cells of a sample of Panax ginseng root.

The procedure for preparing samples for IEM was as follows.

Various parts of Panax ginseng, including the 1) tip region, 2) middle portion, 3) region of root emergence, 4) rhizome, 5) middle portion of the leaf stem, and 6) middle portion of the leaf, were used (Fig. 2). The tissue slices of each part (200 μm thick) were fixed in a fixative comprising 4% paraformaldehyde, 5% glutaraldehyde and 0.05 M HEPES KOH buffer (pH 7.2) for 1 h at 4°C. The fixed tissue slices were cut into small blocks and dehydrated with graded ethanol series at -20°C. Finally the tissue blocks were embedded in LR White. The resin is polymerized under UV light overnight at -20°C and for 6 h at room temperature. (7)

Works Cited

(1) — United States Pharmacopoeia 32-NF27 Page 1026

Pharmacopeial Forum: Volume №30(2) Page 569

(2) — United States Pharmacopoeia 32–NF27 Page 1022

Pharmacopoeial Forum: Volume №30(2) Page 563

(3) — Ph. Eur. monograph 1523

(4) — British Pharmacopoeia IV — Appendices

Appendix XI D. Foreign Matter — Ph. Eur. method 2.8.2

(5) — British Pharmacopoeia IV — Appendices

Appendix XI J. Total Ash — B.P method I

(6) — British Pharmacopoeia IV — Appendices

Appendix XI K. Acid-Insoluble Ash — B.P method I

(7) — Immunofluorescence and Immunoelectron Microscopic Localization of Medicinal Substance, Rb1, in Several Plant Parts of Panax ginseng

Current Drug Discovery Technologies, 2011, 8, 51–59 — Yokota et al.