Licorice
(lik' o rish).
DEFINITION
Licorice consists of the roots, rhizomes, and stolons of Glycyrrhiza glabra L. or Glycyrrhiza uralensis Fish. ex DC. (Fam. Fabaceaeae). It contains NLT 2.5% of glycyrrhizic acid (C42H62O16), calculated on the dried basis.
IDENTIFICATION
• A. Thin-Layer Chromatographic Identification Test
Standard solution:
5 mg/mL of USP Glycyrrhizic Acid RS in a mixture of alcohol and water (7:3)
Sample solution:
2 g of pulverized Licorice in 10 mL of a mixture of alcohol and water (7:3). Heat by shaking on a water bath for 5 min, cool, and filter.
Chromatographic system
Adsorbent:
0.25-mm layer of chromatographic silica gel mixture
Application volume:
2 µL
Developing solvent system:
Butyl alcohol, glacial acetic acid, and water (7:1:2)
Analysis
Samples:
Standard solution and Sample solution
Develop the chromatogram in an unsaturated chamber to a length of 10 cm. Examine the plate under 254-nm light.
Acceptance criteria:
The chromatograms show a dark purple zone, among other spots, due to glycyrrhizic acid at an RF value of 0.4.
COMPOSITION
• Content of Glycyrrhizic Acid
Diluent:
Alcohol and water (1:1)
Solution A:
Diluted acetic acid (1 in 15)
Mobile phase:
Acetonitrile and Solution A (2:3)
Standard solution:
0.25 mg/mL of USP Glycyrrhizic Acid RS in Diluent
Sample solution:
Transfer 500 mg of Licorice, reduced to a powder, to a suitable flask. Add 70 mL of Diluent, shake for 15 min, centrifuge, and decant the supernatant into a 100-mL volumetric flask. Mix the residue with 25 mL of Diluent, shake for 15 min, centrifuge, and add the supernatant to the volumetric flask. Dilute with Diluent to volume, and filter.
Chromatographic system
Mode:
LC
Detector:
UV 254 nm
Column:
4.6-mm × 15-cm; packing L1
Flow rate:
0.6 mL/min
Injection size:
20 µL
System suitability
Sample:
Standard solution
Suitability requirements
Column efficiency:
NLT 5000 theoretical plates determined from glycyrrhizic acid
Tailing factor:
NMT 2.0 for the glycyrrhizic acid peak
Relative standard deviation:
NMT 2.0%
Analysis
Samples:
Standard solution and Sample solution
Calculate the percentage of glycyrrhizic acid (C42H62O16) in the portion of Licorice taken:
Result = (rU/rS) × CS × (V/W) × 100
| rU | = | = peak area of glycyrrhizic acid from the Sample solution |
| rS | = | = peak area of glycyrrhizic acid from the Standard solution |
| CS | = | = concentration of USP Glycyrrhizic Acid RS in the Standard solution (mg/mL) |
| V | = | = final volume of the Sample solution (mL) |
| W | = | = weight of Licorice taken to prepare the Sample solution (mg) |
Acceptance criteria:
NLT 2.5% on the dried basis
CONTAMINANTS
• Heavy Metals, Method III 
231
:
NMT 30 µg/g
231:
NMT 30 µg/g
• Articles of Botanical Origin, Pesticide Residues 561:
Meets the requirements
561:
Meets the requirements
SPECIFIC TESTS
• Botanic Characteristics
Macroscopic:
The terrestrial stem is nearly cylindrical, 0.5–3.0 cm in diameter, and over 1 m in length; it is externally dark brown to red-brown and longitudinally wrinkled. It often has lenticels, small buds, and scaly leaves. The transverse section reveals a rather clear border between the phloem and the xylem, and a radial structure that often has radiating splits.
Microscopic:
The transverse section reveals several yellow-brown cork layers, and a layer of phelloderm that is 1–3 cells thick. The cortex exhibits medullary rays, and obliterated sieve portions radiate alternately. The phloem exhibits groups of phloem fibers, which are surrounded by crystal cells, with thick but incompletely lignified walls. The vessels are accompanied by xylem fibers, which are surrounded by crystal cells, and by xylem parenchyma cells. The parenchyma cells contain starch grains, and often contain single crystals of calcium oxalate.
• Loss on Drying 731:
Dry a sample at 105
for 6 h: it loses NMT 12.0% of its weight.
731:
Dry a sample at 105 for 6 h: it loses NMT 12.0% of its weight.
• Articles of Botanical Origin, Total Ash 561:
NMT 7.0%
561:
NMT 7.0%
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Preserve in well-closed containers. Store in a cool, dry place.
• Labeling:
The label states the Latin binomial and, following the official name, the part of the plant contained in the article.
• USP Reference Standards 11
11
USP Glycyrrhizic Acid RS 
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Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Maged H. Sharaf, Ph.D.
Principal Scientific Liaison 1-301-816-8318 |
(DS2010) Monographs - Dietary Supplements |
| Reference Standards | RS Technical Services 1-301-816-8129 rstech@usp.org |
USP35–NF30 Page 1362