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      Aloes is the solid residue obtained by evaporating the juice which drains from the leaves cut from various species of Aloe (Family Asphodelaceae).

BARBADOS ALOES
Curaçao Aloes
       Barbados Aloes is the aloes obtained from Aloe vera (L.) Burm. f. (A. barbadensis Miller). It contains not less than 16.0 per cent of aloin (C₂₁H₂₂O₉), calculated on the dried basis.

Constituents Barbados Aloes contains anthraquinone glycosides, the principal one of which is aloin (aloe-emodin anthrone C-10 glucoside). It also contains chromones such as aloeresin A and aloesin, and anthraquinones.

Description Dark brown masses, slightly shiny or opaque with a conchoidal fracture, or brown powder. Odour, strong and characteristic; taste, nauseous and bitter.

Solubility Partly soluble in boiling water; soluble in hot ethanol.

Packaging and storage Barbados Aloes shall be kept in tightly closed containers and stored at a temperature not exceeding 25°.

Identification
       A. Mix 1 g, in fine powder, with 25 mL of cold water. Shake the mixture occasionally for 2 hours, filter, and wash the filter and residue with sufficient cold water to make 100.0 mL: a dark orange colour is observed when viewed in a bulb of a 100-mL volumetric flask.
       B. To 5 mL of the filtrate obtained in the test for Identification A, add 2 mL of nitric acid and mix: a reddish orange colour is produced.
       C. Carry out the test as described in the “Thin-Layer Chromatography” (Appendix 3.1).
       Standard solution A solution containing 1.0 mg per mL of Aloin RS in methanol.
       Test solution Dissolve 500 mg, in fine powder, in 10 mL of methanol. Sonicate for 15 minutes, centrifuge or filter, and use the supernatant or the filtrate.
       Adsorbent Silica gel GF254 (HPTLC plate)
       Mobile phase Ethyl acetate, methanol, and water (100:17:13)
       Application Apply 2 μL of Standard solution and 5 μL of Test solution as 8-mm bands.
       Development and drying Allow the solvent front to ascend 6 cm above the line of application. Dry the developed plate in air.
       Detection Spray the plate with a 10 per cent w/v solution of potassium hydroxide in methanol (prepared in an ice-bath), heat at 110° for 5 minutes and observe the result. Examine the plate under visible light and ultraviolet light (366 nm).
       Results When examined under visible light, the test solution shows a brown band due to aloin at about the middle of the chromatogram, corresponding in colour and Rf to the band shown by the standard solution. The test solution shows a violet band due to 7-hydroxyaloin just below the band due to aloin.
       When examined under ultraviolet light (366 nm), the test solution shows a yellow fluorescent band due to aloin at about the middle of the chromatogram, corresponding in colour and Rf to the band shown by the standard solution and a light blue fluorescent band due to aloesin at about the upper third of the chromatogram.
       Loss on drying Not more than 12.0 per cent w/w, determined on 2 to 5 g, in No. 425 powder, by drying at 105 for 5 hours (Appendix 4.15).
       Total ash Not more than 4.0 per cent w/w (Appendix 7.7).
       Ethanol-insoluble substance Not more than 10.0 per cent w/w. Boil about 1 g of powdered Barbados Aloes, accurately weighed, with 50 mL of ethanol on a water-bath for 30 minutes under a reflux condenser. Filter through a small dried and tared filter paper or a suitable dried and tared filtering crucible, and wash the residue on the filter with ethanol until the last washing is colourless. Dry the residue at 105 to constant weight and weigh.

Water-soluble extractive Not less than 50 per cent w/w (Appendix 7.12).

Assay Carry out the determination as described in the “Liquid Chromatography” (Appendix 3.5).
       Standard preparation A solution containing 0.1 mg per mL of Aloin RS in a mixture of equal volumes of methanol and water. (Note The standard preparation is stable for 8 hours at a temperature of 25.)
       Assay preparation: Transfer about 100 mg, in fine powder, accurately weighed, to a 100-mL volumetric flask, and add 75 mL of methanol. Sonicate for 30 minutes, cool to room temperature, adjust with methanol to volume, and mix. Filter. (Note The assay preparation is stable for 8 hours at a temperature of 25°.)
       Mobile phase: Acetonitrile and water (3:7)
       Chromatographic system
       DETECTOR Ultraviolet light (295 nm)
       COLUMN A stainless steel column (25 cm × 4.6 mm), packed with octadecylsilane chemically bonded to porous silica or ceramic microparticles (5 μm), end-capped.
       COLUMN TEMPERATURE 43°±1°
       FLOW RATE 1.0 mL per minute
       System Suitability
       SAMPLE Standard preparation
       Suitability requirements
       COLUMN EFFICIENCY Not less than 2000 theoretical plates for the aloin peak
       SYMMETRY FACTOR Not more than 2.0 for the aloin peak
       Relative standard deviation Not more than 2.0 per cent determined from the aloin peak.
       Procedure Separately inject equal volumes (about 20 μL) of Standard preparation and Assay preparation into the chromatograph and measure the responses for the major peaks.
       Calculation Calculate the content of C₂₁H₂₂O₉ in the Barbados Aloes taken, using the declared content of C₂₁H₂₂O₉ in Aloin RS.

CAPE ALOES

       Cape Aloes is the aloes obtained from Aloe ferox Miller, and hybrids of this species with A. africana Miller or A. spicata Baker. It contains not less than 6.0 per cent of aloin (C₂₁H₂₂O₉), calculated on the dried basis.

Constituents Cape Aloes contains anthraquinone glycosides, the principal one of which is aloin (aloe-emodin anthrone C-10 glucoside). It also contains chromones such as aloeresin A and aloesin.

Description Dark brown masses, tinged with green, with a shiny conchoidal fracture, or a greenish brown powder. Odour, strong and characteristic; taste, nauseous and bitter.

Solubility Partly soluble in boiling water; soluble in hot ethanol.

Packaging and storage Cape Aloes shall be kept in tightly closed containers and stored at a temperature not exceeding 25°.

Identification
       A. Mix 1 g, in fine powder, with 25 mL of cold water. Shake the mixture occasionally for 2 hours, filter, and wash the filter and residue with sufficient cold water to make 100.0 mL: a greenish yellow colour is observed when viewed in a bulb of a 100-mL volumetric flask.
       B. To 5 mL of the filtrate obtained in the test for Identification A, add 2 mL of nitric acid: a reddish brown colour that changes rapidly to green is produced.
       C. Carry out the test as described in the “Thin-Layer Chromatography” (Appendix 3.1).
       Standard solution, Adsorbent, Mobile phase, Application, Development and drying, and Detection Proceed as directed in the Identification under Barbados Aloes.
       Test solution Dissolve 500 mg, in fine powder, in 10 mL of methanol. Sonicate for 15 minutes, centrifuge or filter, and use the supernatant or the filtrate.
       Results When examined under visible light, the test solution shows a brown band due to aloin at about the middle of the chromatogram, corresponding in colour and Rf to the band shown by the standard solution. The test solution shows no violet bands due to 7-hydroxyaloin just below the band due to aloin.
       When examined under ultraviolet light (366 nm), the solution shows a yellow fluorescent band due to aloin at about the middle of the chromatogram, corresponding in colour and Rf to the band exhibited by the standard solution and a light blue fluorescent band due to aloesin at about the upper third of the chromatogram.

Loss on drying Not more than 10.0 per cent w/w, determined on 2 to 5 g, in No. 425 powder, by drying at 105° for 5 hours (Appendix 4.15).

Total ash Not more than 4.0 per cent w/w (Appendix 7.7).

Ethanol-insoluble substance Not more than 10.0 per cent w/w. Boil about 1 g of powdered Cape Aloes, accurately weighed, with 50 mL of ethanol on a water-bath for 30 minutes under a reflux condenser. Filter through a small dried and tared filter paper or a suitable dried and tared filtering crucible, and wash the residue on the filter with ethanol until the last washing is colourless. Dry the residue at 105° to constant weight and weigh.

Water-soluble extractive Not less than 50.0 per cent w/w (Appendix 7.12).

Assay Carry out the determination as described in the “Liquid Chromatography” (Appendix 3.5).
       Standard preparation, Mobile phase, Chromatographic System, System Suitability, Suitability requirements, Procedure, and Calculation Proceed as directed in the Assay under Barbados Aloes.
       Assay preparation Transfer about 200 mg, in fine powder, accurately weighed, to a 100-mL volumetric flask, and add 75 mL of methanol. Sonicate for 30 minutes, cool to room temperature, adjust with methanol to volume, and mix. Filter.

ALOES, POWDERED

Powdered Aloe
Thai name ยาดาผง (YA DAM PHONG)

       Complies with the requirements for content of aloin, Identification, Loss on drying, Total ash, Ethanol-insoluble substance, and Water-soluble extractive stated under Barbados Aloes or Cape Aloes, and with the following requirements.

Description Yellowish brown to dark reddish brown powder. Odour, strong and characteristic; taste, nauseous and bitter. When mounted in lactophenol and examined under a microscope, it is seen to consist of yellowish to reddish brown angular or irregular fragments, which are composed of masses of small acicular crystals (Barbados Aloes) or either amorphous and structureless (Cape Aloes); the powder ultimately dissolves in the mountant.
Solubility Almost entirely soluble in ethanol (60 per cent).
Packaging and storage Powdered Aloes shall be kept in tightly closed containers and stored at a temperature not exceeding 25°.