Aloes - Source, Diagnostic Characters, Constituents and Uses


Source, Diagnostic Characters, Constituents and Uses 


At the end of this lecture, student will be able to

Discuss the source, diagnostic characters, constituents and uses of Aloes



• Aloe, Musabbar, Kumari


• 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)


• 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)


Fragments with large number of very small needles or slender prisms


Transparent, brown, angular or irregular fragments


Fragments with large prisms in groups are in dispersed form


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)


• 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


Add CCl4, Organic layer separated and ammonia added


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


• 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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