Aloes – Source, Diagnostic Characters, Constituents and Uses

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

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