Powdered Centella asiatica Extract
DEFINITION
Powdered Centella asiatica Extract is prepared from Centella asiatica by extraction with alcohol, methanol, acetone, or a mixture of these solvents. The ratio of plant material to extract is between 65:1 and 30:1. It contains NLT 90.0% and NMT 110.0% of the labeled amount of triterpene derivatives; the labeled amount of triterpene derivatives is NMT 40%, calculated on the dried basis as the sum of madecassoside, asiaticoside B, asiaticoside, madecassic acid, terminolic acid, and asiatic acid. It may contain suitable added substances as carriers.
IDENTIFICATION
•  A. Thin-Layer Chromatographic Identification Test
Standard solution A:  0.5 mg/mL of USP Asiaticoside RS in methanol
Standard solution B:  10 mg/mL of USP Powdered Centella asiatica Extract RS in methanol. Sonicate for about 10 min, centrifuge, and use the supernatant.
Sample solution:  Transfer an amount of Powdered Centella asiatica Extract equivalent to about 5 mg of triterpene derivatives to a centrifuge tube. Add 5 mL of methanol, sonicate for 10 min, centrifuge, and use the supernatant.
Adsorbent:  Chromatographic silica gel with an average particle size of 10–15 µm (TLC plates) or with an average particle size of 5 µm (HPTLC plates)
Application volume:  10 µL (TLC plates) or 4 µL (HPTLC plates)
Developing solvent system:  A mixture of methylene chloride, methanol, and water (14:6:1)
Spray reagent:  A solution of 10% sulfuric acid in methanol. [Note—Prepare fresh. ]
Analysis 
Samples:  Standard solution A, Standard solution B, and Sample solution
Apply the samples as bands to a suitable thin-layer chromatographic plate (see Chromatography 621). Use a saturated chamber. Develop the chromatograms until the solvent front has moved up about three-fourths of the plate. Remove the plate from the chamber, dry, spray with the Spray reagent, heat for 3 min at 120, and examine under visible light.
Acceptance criteria:  The Sample solution chromatogram exhibits a violet band in the lower third of the plate due to asiaticoside, corresponding in color and RF to that in Standard solution A; a violet band due to madecassoside at an RF lower than that of asiaticoside; and two additional violet bands in the upper third of the plate due to asiatic acid and madecassic acid. Bands detected in the Sample solution correspond in position and color to bands in Standard solution B. Other minor bands may be observed in the Sample solution and Standard solution B.
•  B. HPLC Identification Test: The Sample solution chromatogram from the test for Content of Triterpene Derivatives shows a peak at the retention time corresponding to that of asiaticoside in Standard solution A. Identify other triterpene derivative peaks in the Sample solution by comparison with the chromatogram of Standard solution B and the reference chromatogram provided with the lot of USP Powdered Centella asiatica Extract RS being used. The Sample solution shows additional peaks corresponding to madecassoside and asiaticoside B (these two peaks may co-elute), madecassic acid, terminolic acid, and asiatic acid.
COMPOSITION
•  Content of Triterpene Derivatives
Solution A:  Dilute 3 mL of phosphoric acid with water to 1000 mL, mix, filter, and degas.
Solution B:  Acetonitrile
Mobile phase:  See the gradient table below.
Time
(min)
Solution A
(%)
Solution B
(%)
0 78 22
65 45 55
66 5 95
75 5 95
76 78 22
85 78 22
Standard solution A:  0.1 mg/mL of USP Asiaticoside RS in methanol
Standard solution B:  Sonicate a portion of USP Powdered Centella asiatica Extract RS in methanol to obtain a solution with a concentration of about 5.0 mg/mL. Before injection, pass through a membrane filter of 0.45-µm or finer pore size, discarding the first few mL of the filtrate.
Sample solution:  Sonicate a portion of Powdered Centella asiatica Extract in methanol to obtain a solution with a concentration of about 5.0 mg/mL. Before injection, pass through a membrane filter of 0.45-µm or finer pore size, discarding the first few mL of the filtrate.
Chromatographic system 
Mode:  LC
Detector:  UV 200 nm
Column:  4.6-mm × 25-cm; 5-µm packing L1
Flow rate:  1.0 mL/min
Injection size:  10 µL
System suitability 
Samples:  Standard solution A and Standard solution B
Suitability requirements 
Chromatogram similarity:  The chromatogram from Standard solution B is similar to the reference chromatogram provided with the lot of USP Powdered Centella asiatica Extract RS being used.
Tailing factor:  Between 0.8 and 2.0 for the asiaticoside peak, Standard solution A
Resolution:  NLT 1.5 between the madecassic acid and terminolic acid peaks, Standard solution B
Relative standard deviation:  NMT 2.0% determined from the asiaticoside peak in repeated injections, Standard solution A
Analysis 
Samples:  Standard solution A, Standard solution B, and Sample solution. [Note—Standard solution A, Standard solution B, and the Sample solution are stable for 48 h at room temperature. ]
Using the chromatograms of Standard solution A, Standard solution B, and the reference chromatogram provided with the lot of USP Powdered Centella asiatica Extract RS being used, identify the retention times of the peaks corresponding to different triterpene derivatives. The approximate relative retention times of the different triterpene derivatives are provided in the following table.
Analyte Approximate Relative
Retention Time
Madecassoside 0.71
Asiaticoside B 0.72
Asiaticoside 1.00
Madecassic acid 2.40
Terminolic acid 2.44
Asiatic acid 3.12
Separately calculate the percentages of the sum of madecassoside and asiaticoside B (these two peaks may co-elute), asiaticoside, the sum of madecassic acid and terminolic acid, and asiatic acid in the portion of Powdered Centella asiatica Extract taken:
Result = (rU/rS) × (CS/CU) × F × 100
rU== peak response(s) of the triterpene derivative(s) from the Sample solution
rS== peak response of asiaticoside from Standard solution A
CS== concentration of USP Asiaticoside RS in Standard solution A (mg/mL)
CU== concentration of Powdered Centella asiatica Extract in the Sample solution (mg/mL)
F== conversion factors for analytes: 1.00 for asiaticoside, 1.017 for the sum of madecassoside and asiaticoside B, 0.526 for the sum of madecassic acid and terminolic acid, and 0.509 for asiatic acid
Acceptance criteria:  Add the percentages of different triterpene derivatives: NLT 90.0% and NMT 110.0% of the labeled amount of triterpene derivatives; the labeled amount of triterpene derivatives is NMT 40%, calculated on the dried basis.
CONTAMINANTS
•  Heavy Metals, Method III 231: NMT 20 ppm
•  Microbial Enumeration Tests 2021: The total aerobic microbial count does not exceed 104 cfu per g. The total combined yeast and mold count does not exceed 103 cfu per g.
•  Microbiological Procedures for Absence of Specified Microorganisms 2022: Meets the requirements of the tests for absence of Salmonella species and Escherichia coli
SPECIFIC TESTS
•  Loss on Drying 731: Dry 1.0 g of Powdered Centella asiatica Extract at 105 for 2 h: it loses NMT 5% of its weight.
•  Other Requirements: Meets the requirements of the test for Residual Solvents under Botanical Extracts 565
ADDITIONAL REQUIREMENTS
•  Packaging and Storage: Preserve in well-closed containers, protected from light and moisture, and store at controlled room temperature.
•  Labeling: The label states the Latin binomial and, following the official name, the part of the plant from which the article was derived. It meets other labeling requirements under Botanical Extracts 565.
•  USP Reference Standards 11
USP Asiaticoside RS Click to View Structure
USP Powdered Centella asiatica Extract RS
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Monograph Maged H. Sharaf, Ph.D.
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2021 Radhakrishna S Tirumalai, Ph.D.
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2022 Radhakrishna S Tirumalai, Ph.D.
Principal Scientific Liaison
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