Aloe

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

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1 DEFINITION

Aloe is the dried latex of the leaves of Aloe vera (L.) Burm.f. (syn. Aloe barbadensis Mill.), known in commerce as aloe vera, Curaçao aloe, or Barbados aloe; or of the leaves of Aloe ferox Mill., or of hybrids of Aloe ferox Mill. with Aloe africana Mill. and Aloe spicata L.f., known in commerce as Cape aloe (Family Asphodelaceae) (USP 1-May-2023) Aloe vera contains NLT 16.0% of aloin A (USP 1-May-2023) and Cape aloe and its hybrids contain NLT 6.0% of aloin A (USP 1-May-2023), both calculated on the dried basis.

2 IDENTIFICATION

2.1 A

Sample: 1 g, finely powdered

Analysis: In a 100-mL volumetric flask, mix the Sample with 25 mL of cold water. Shake the mixture occasionally for 2 h, filter, and wash the filter and residue with sufficient cold water until the filtrate measures 100 mL.

Acceptance criteria: The color of the filtrate, viewed in the bulb of a 100-mL volumetric flask, is dark orange with Curaçao aloe and greenish-yellow with Cape aloe. The filtrate darkens on standing. [NOTE-Reserve the filtrate for Identification B.]

2.2 B

Sample: 5 mL of the filtrate obtained in Identification A

Analysis: Add 2 mL of nitric acid to the Sample, and mix.

Acceptance criteria: The mixture exhibits a reddish-orange color with aloe vera and a reddish-brown color that changes rapidly to green with Cape aloe.

Change to read:

2.3 C. HPTLC FOR ARTICLES OF BOTANICAL ORIGIN (203) (USP 1-MAY-2023)

Standard solution: 1.0 mg/mL of USP Aloin A RSA (USP 1-May-2023) in methanol

Sample solution: 0.5 g of finely powdered Aloe in 10 mL of methanol. Sonicate for 15 min, centrifuge or filter, and use the supernatant or the filtrate.

Chromatographic system (See standard parameters as defined in HPTLC for Articles of Botanical Origin (203), Table 1.) (USP 1-May-2023)

Application volume: 2 µL of the Standard solution and 5 µL of the Sample solution, as 8-mm bands (USP 1-May-2023)

Developing solvent system: Ethyl acetate, methanol, and water (100:17:13) (USP 1-May-2023)

Derivatization reagent: 10% potassium hydroxide solution in methanol. Prepare in an ice bath.

Analysis

Samples: Standard solution and Sample solution

Apply the Samples as bands to a suitable HPTLC plate. Use a saturated chamber. Develop the chromatograms, dry in air, derivatize with Derivatization reagent, and heat at 110° for 5 min. Examine under white light and long-wave UV light.

Acceptance criteria

Under white light: The Sample solution exhibits a brown band due to aloin A (USP 1-May-2023) at about the middle of the chromatogram, corresponding in color and R to the band exhibited by the Standard solution. The Sample solution containing aloe vera exhibits an additional violet band due to 7-hydroxyaloin right below the aloin A (USP 1-May-2023) band. The Sample solution containing Cape aloe lacks the violet band due to 7-hydroxyaloin.

Under long-wave UV light: The Sample solution exhibits a yellow fluorescence band due to aloin A (USP 1-May-2023), corresponding in color and R, to the band exhibited by the Standard solution, as well as a light blue fluorescence band due to aloesin (USP 1-May-2023) in the lower-third of the chromatogram.

3 COMPOSITION

3.1 CONTENT OF ALOIN (USP 1-MAY-2023)

Mobile phase: A mixture of acetonitrile and water (3:7)

Standard solution: 0.1 mg/mL of USP Aloin ARS (USP 1-May-2023) in methanol and water (1:1)

Sample solution: Transfer about 0.1 g of aloe vera or 0.2 g of Cape aloe, finely powdered and accurately weighed, to a 100-mL volumetric flask and add about 75 mL of methanol. Sonicate for 30 min, cool to room temperature, adjust with methanol to volume, and mix. Before injection, pass through a PTFE membrane filter of 0.45-µm pore size, discarding the first few milliliters of the filtrate.

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 295 nm

Column: 4.6-mm x 25-cm; end-capped 5-um packing L1

Column temperature: 43 ± 1°

Flow rate: 1.0 mL/min

Injection volume: 20 µL

System suitability

Sample: Standard solution

Suitability requirements

Column efficiency: NLT 2000 theoretical plates for the aloin A (USP 1-May-2023) peak

Tailing factor: NMT 2.0 for the aloin A (USP 1-May-2023) peak

Relative standard deviation: NMT 2.0% for the aloin A (USP 1-May-2023) peak in repeated injections

Analysis

Samples: Standard solution and Sample solution

[NOTE-The Standard solution and Sample solution are stable for 8 h at room temperature.]

Using the chromatogram of the Standard solution, identify the retention time of the peak corresponding to aloin A (USP 1-May-2023) in the Sample solution.

Calculate the percentage of aloin A (USP 1-May-2023) in the portion of Aloe taken:

Result = (r_U/r_S) x C_S x (V/W) x 100

r_U = peak area of aloin A (USP 1-May-2023) from the Sample solution

r_S = peak area of aloin A (USP 1-May-2023) from the Standard solution

C_S = concentration of USP Aloin A RS (USP 1-May-2023) in the Standard solution (mg/mL)

V = final volume of the Sample solution (mL)

W = weight of Aloe taken to prepare the Sample solution (mg)

Acceptance criteria: Aloe vera contains NLT 16.0% of aloin A (USP 1-May-2023) and Cape aloe or its hybrids contain NLT 6.0% of aloin A (USP 1-May-2023), both on the dried basis.

3.2 WATER-SOLUBLE EXTRACTIVE

Sample: 2 g of powdered Aloe

Analysis: Macerate the Sample in 70 mL of water in a suitable flask. Shake the mixture for 8 h at 30-min intervals and allow it to stand for 16 h without shaking. Filter, and wash the flask and residue with small portions of water, passing the washings through the filter until the filtrate is 100.0 mL. Evaporate a 50-mL aliquot of the filtrate in a tared dish on a steam bath to dryness, and dry at 110° to constant weight.

Acceptance criteria: The weight of water-soluble extractive is NLT 50% of the weight of Aloe taken.

4 CONTAMINANTS

ARTICLES OF BOTANICAL ORIGIN (561), Pesticide Residue Analysis: Meets the requirements

5 SPECIFIC TESTS

5.1 LOSS ON DRYING (731).

Sample: Use a powdered sample. If the Aloe is not powdered, crush it in a mortar until it passes through a no. 40 sieve, and mix the ground

material before weighing the sample.

Analysis: Dry the Sample at 105° for 5 h.

Acceptance criteria: NMT 12.0%

5.2 ARTICLES OF BOTANICAL ORIGIN (561), Methods of Analysis, Total Ash

NMT 4.0%

5.3 ALCOHOL-INSOLUBLE SUBSTANCES

Sample: 1 g of powdered Aloe

Analysis: Add the Sample to 50 mL of alcohol in a flask. Heat the mixture to boiling, and maintain at incipient boiling for 15 min, replacing any loss due to evaporation. Remove from the heat and shake at intervals for 1 h. Pass through a small dried and tared filter paper or a dried and tared filtering crucible, and wash the residue on the filter with alcohol until the last washing is colorless. Dry the residue at 105° to constant weight.

Acceptance criteria: The weight of the residue is NMT 10.0% of the weight of Aloe taken.

5.4 BOTANICAL CHARACTERISTICS

Curaçao aloe: Brownish-black, opaque masses. Its fractured surface is uneven, waxy, and somewhat resinous.

Cape aloe: Dusky to dark brown irregular masses, the surfaces of which are often covered with a yellowish powder. Its fracture is smooth and glassy.

Powdered Aloe: Yellow, yellowish brown to olive-brown in color. When mounted in olive oil, it appears as greenish-yellow to reddish-brown irregular fragments, the hues of which depend to some extent upon the thickness of the fragments.

6 ADDITIONAL REQUIREMENTS

USP REFERENCE STANDARDS (11).

USP Aloin A RSA (USP 1-May-2023)