Aloes
Source, Diagnostic
Characters, Constituents and Uses
Objectives
At the
end of this lecture, student will be able to
• Discuss
the source, diagnostic characters, constituents and uses of Aloes
Aloes
Synonym
• Aloe, Musabbar, Kumari
Source
• Dried juice of the leaves of Aloe barbadensis
(Curacao aloes), Aloe perry (Socotrine aloes), Aloe ferox, and
hybrid of this sps with Aloe Africana and Aloe spicata (cape aloes)
Family
• Liliaceae
Geographical source
• Indigenous to eastern and southern Africa, grown in cape
colony, Zanzibar and islands of Socotra
• Also cultivated in many parts of India
Preparation of Aloes
Barbados or curacao aloes (A. barbadensis)
• Islands of aruba and boniare in West Indies
• Transverse cut near the base
• Cut leaves kept along the sides of V shaped wooden troughs
• Collected juice- boiled, latex evaporates, and juice
thickens
• Thick juice poured into gourds or metal containers
Cape aloes (A. ferox)
• Transversely cut leaves kept in circular manner in basin
shaped depression dug in ground, covered with goat skin or canvas
• Leaves placed so that cut ends overlaps
• Kept for 5-6 hrs, juice collected in goat skin
• Juice transferred to large iron kettle, boiled with
continuous stirring
• Poured into wooden boxes
Zanzibar aloes
• Variety origin – not known
• Regarded as variety of Socotrine
• Juice in skin of small carnivorous animals, solidifies
then packed
• Monkey skin aloes – even though skin is not of monkey
Socotrine aloes (A. perryi)
• Island of Socotra and main land of East Africa
• Juice collected in goat skin, allowed to solidify
• Exported in pasty condition
Description of Aloes
Curacao aloes
• Occurs as cape Barbados and livery variety
• Both varieties- strong odour, resemble iodoform
• Intensely bitter
• Brownish black
• Opaque mass
• Waxy, somewhat resinous
• Uneven fractured surface
Cape aloes
• Dark brown or greenish brown to olive brown masses
• Nauseating and bitter taste
• Glassy fracture
• Distinct odour
Socotrine aloes
• Brownish yellow
• Opaque mass
• Pasty or semi-solid consistency
• Conchoidal fracture
• Extremely bitter
• Nauseating odour
• Totally soluble in 60 % alcohol
Zanzibar aloes
• Liver brown colour
• Dull and waxy
• Smooth and even fracture
• Characteristic and disagreeable odour
• Bitter
Powder of Aloes
• Studied in lactophenol (particles gradually solublises,
crystals are clearly seen)
Curacao
Fragments with large number of very small needles or slender
prisms
Cape
Transparent, brown, angular or irregular fragments
Socotrine
Fragments with large prisms in groups are in dispersed form
Zanzibar
Irregular lumps
Constituents of Aloes
Anthraquinone glycosides
• Principal component – Aloin – Mixture of glucosides,
Barbaloin– chief constituent
• Barbaloin – Aloe emodin anthrone C10 glucoside,
water soluble
• Not hydrolysed by heat with dilute acid or alkali
• Decomposed by ferric chloride to aloe –
emodin-anthrone, little aloe-emodin, glucose (oxidative hydrolysis)
Others
• Isobarbaloin, β Barbaloin, aloe emodin,
• Resin – Aloesin – purgative action
• Aloetic acid, saponins, mucopolysaccharides, glucosamines,
hexuronic acid, coniferyl alcohol etc
Tests For specific variety of Aloes
General
test
• 1 g boiled in 10 ml water, fliter with kieselghur,
filtrate used for bromine and Schoenteten’s test
Bromine test
• Filtrate + freshly prepared bromine solution – pale
yellow ppt (tetrabromaloin)
Schoenteten’s test (Borax test):
• Filtrate + Borax, shaken till borax dissolves
• Few drops added to test tube full of water – green
fluorescence
Special
tests
Nitrous acid test
Aq. Solution of aloes + sodium nitrite + Acetic acid
• Curacao aloes – sharp pink to carmine colour
• Cape aloes – faint pink
• Socotrine/Zanzibar aloes – very less change in colour (isobarbaloin)
Nitric acid test
Aq. Solution or drug + nitric acid
• Curacao aloes – deep brownish red colour
• Cape aloes – Brownish colour to green
• Socotrine aloes – Pale brownish to yellow colour
• Zanzibar aloes – Yellowish brown colour
Kupraloin test (klunge’s isobarbaloin test)
Dilute Aq. Solution + drop of saturated copper sulphate
solution + little of NaCl + excess of 90% alcohol
• Curacao aloes – wine red colour persistent for hours
• Cape aloes – Faint, rapidly changes to yellow
• Socotrine aloes – no colour
• Zanzibar aloes – no colour
Modified anthraquinone test
For C glycosides- aloe emodin
Aq. Solution + FeCl3
+ dil HCl – oxidative hydrolysis of aloe emodin
â
Add CCl4,
Organic layer separated and ammonia added
â
Ammoniacal layer
shows rose pink to cherry red colour
Uses of Aloes
• Purgative – colon
• Aloin is used instead of aloes
• To counter effect gripping action, given along with
carminatives
• Aloe gel- inner parenchyma of leaf
v Topical
and cosmetic products – moisturizing property
• Anti-inflammatory property
v Increases
the removal of dead tissues – Aloctine (stimulates macrophage production)
• Pain, itching, slow down ulceration, keratosis
Adulterants/Substitutes of Aloes
• Natal aloes – resemble cape aloe microscopically-
as substitute
v Natalion,
homonatalion, resin with nataloresinotannol
v Weak
purgative
• Mocha aloes –brittle, black, glassy, strong odour
• Adulterated with black catechu, stones, iron pieces
• Aloe alcohol extract- deep brown colour under UV, black
catechu- black colour under UV
Summary
• Aloes – Dried juice of the leaves of Aloe barbadensis
(Curacao aloes), Aloe perry (Socotrine aloes), Aloe ferox, and
hybrid of this sps with Aloe Africana and Aloe spicata (cape
aloes), Anthraquinone glycosides – Aloin, Barbaloin- chief constituent
• Bromine test (tetrabromaloin), Schoenteten’s test (Borax
test), Modified anthraquinone test, Purgative