Aloe
Aloe
Aloe is the dried juice of the
leaves mainly of Aloe ferox Miller, or of hybrids of the species with Aloe africana Miller or Aloe spicata Baker (Liliaceae).
It contains not less than 4.0z of
barbaloin, calculated on the basis of dried material.
Description:
Aloe occurs as blackish brown
to dark brown, irregular masses; sometimes the external surface covered with a
yellow powder; the fractured surface smooth and glassy.
Odor, characteristic; taste,
extremely bitter.
Identification:
(1) Dissolve 0.5 g of pulverized Aloe in 50 mL of water by warming.
After cooling, add 0.5 g of siliceous earth, and filter. Perform the following
tests using the filtrate as the sample solution.
(i) Dissolve 0.2 g of sodium
tetraborate decahydrate in 5 mL of the sample solution by warming in a water
bath. Add a few drops of this solution into 30 mL of water, and shake: a green
fluorescence is produced.
(ii) Shake 2 mL of the sample
solution with 2 mL of nitric acid: a yellow-brown color which changes gradually
to green is produced. Then warm this colored solution in a water bath: the
color of the solution changes to red-brown.
(2) To 0.2 g of pulverized Aloe add 10 mL of methanol, shake for 5
minutes, filter, and use the filtrate as the sample solution. Separately,
dissolve 1 mg of barbaloin for thin- layer chromatography in 1 mL of methanol,
and use this solution as the standard solution. Perform the test with these solutions
as directed under Thin-layer Chromatography. Spot 10 mL each of the sample
solution and standard solution on a plate of silica gel for thin-layer
chromatography. Develop the plate with a mixture of ethyl acetate, acetone,
water and acetic acid (100) (20:5:2:2) to a distance of about 10 cm, and
air-dry the plate. Examine under ultraviolet light (main wavelength: 365 nm):
one spot among several spots from the sample solution and a red fluorescent
spot from the standard solution show the same color tone and the same Rf
value.
Purity:
(1) Resin.Warm 0.5 g of pulverized Aloe with 10 mL of diethyl ether
on a water bath, and filter. Wash the residue and the filter paper with 3 mL of
diethyl ether. Combine the filtrate and the washing, and evaporate the diethyl ether
solution: the mass of the residue is not more than 5.0 mg.
(2) Ethanol-insoluble substances.Boil 1.0 g of pulverized Aloe with
50 mL of ethanol (95) on a water bath for 30 minutes under a reflux condenser.
Filter the warm mixture through a tared glass filter (G4), and wash the residue
on the filter with ethanol (95) until the last washing becomes colorless. Dry
the residue at 105oC for 5 hours, and weigh: the mass of the residue
is not more than 0.10 g.
Loss on drying:
Not more than 12.0z.
Total ash:
Not more than 2.0z.
Extract content:
Water-soluble extract: not less
than 40.0z. Assay Weigh accurately about 0.1 g of pulverized Aloe, add 40 mL of
methanol, and heat under a reflex condenser on a water bath for 30 minutes.
After cooling, filter, and add methanol to the filtrate to make exactly 50 mL.
Pipet 5 mL of the solution, add methanol to make exactly 10 mL, and use this solution
as the sample solution. Separately, weigh accurately about 10 mg of barbaloin
for assay, previously dried in a desiccator (in vacuum, phosphorus (V) oxide)
for 24 hours, add 40 mg of oxalic acid dihydrate, an issolve in methanol to
make exactly 100 mL. Pipet 5 mL of the solution, add methanol to make exactly
10 mL, and use this solution as the standard solution. Perform the test with exactly
5 mL each of the sample solution and standard solution as directed under Liquid
Chromatography according
to the following conditions, and determine the peak areas of barbaloin, AT and
AS, of both solutions.
Amount (mg) of barbaloin＝ MS × AT/AS
× 1/2
MS: Amount (mg) of
barbaloin for assay
Operating conditions.
Detector: An ultraviolet
absorption photometer (wave-length: 360 nm).
Column: A stainless steel
column 6 mm in inside diameter and 15 cm in length, packed with
octadecylsilanized silica gel for liquid chromatography (5 mm in particle
diameter).
Column temperature: A constant
temperature of about 30oC.
Mobile phase: A mixture of
water, acetonitrile and acetic acid (100) (74:26:1).
Flow rate: Adjust the flow rate
so that the retention time of barbaloin is about 12 minutes.
System suitability.
System performance: Dissolve 10
mg of barbaloin for assay add 40 mg of oxalic acid dihydrate, in methanol to make
100 mL. To 5 mL of the solution add 1 mL of a solution of ethenzamide in
methanol (1 in 2000) and methanol to make 10 mL. When the procedure is run with
5 mL of this solution under the above operating conditions except the wavelength
of 300 nm, barbaloin and ethenzamide are eluted in this order with the
resolution between these peaks being not less than 2.0.
System repeatability: When the
test is repeated 6 times with 5 mL of the standard solution under the above operating
conditions, the relative standard deviation of the peak area of barbaloin is
not more than 1.5z.
Containers and storage:
Containers.Well-closed containers.
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