Chemical Constituents
Aloe contains a mixture of crystalline glycosides known as aloin 4-5% in cape Aloe 18-25% in Curacao Aloe, resin(16-37%),emodin and volatile oil. It also possess the anthraquinone glycoside like barbaloin(aloe-emodin anthrone C-10 glucoside),chrysophanic acid,B-barbaloin and iso-barbaloin.
The active constituents of aloe vary qualitatively and quantitatively according to the species from which the drug is obtained.
Analyses have elevated that Curacao also is superior to cape aloe because it contains two and one half times as much aloe emodin.Curacao aloe also contains an noticeable amount of free and combined chrysophanic acid not present in the other types.

The principal constituents of aloin are barbaloin,isobarbaloin,B-barbaloin,aloe emodin and resins.
During storage of aloin the content of the aloe-emodin inreases.In additin to these flavonoids oxanthraquniones,courmarins,aminoacids,monosaccharides,polysaccharides oils,sterols,triterpenes,vitamin c and group B vitamins citric,c-malic and formic acids are present in all aloes.
Presence of minerals,B,P.Al,Mg,Ca,Si,Fe,Pb,Cr,Ba,Ag,Zn and Sr have been confirmed.
Chemical Tests
General test
Bromine Test:
To 2ml of solution of aloes add 2ml of freshly prepared solution of bromine.A pale yellow precipitate if tetrabarbromaline is produced.This test is not specific for aloes.
Special Test:
Nitric acid test to 5 ml of solution of aloes gives a brownish color rapidly changing to green.
Barbados a deep brownish-red.
Socotrine a pale brownish-yellow.
Zanzibar a yellow brown color.
Nitric acid can also applied direct to the powdered drugs with similar results.
Uses of Aloe Vera
Aloe is Pharamaceutic aid for compound benzoin tincture and a cathartic.When used as a cathartic it acts chiefly on the large intestine. Aloe glycoside elicit a relatively advocate a preferential use of other cathartic substances. Aloe available with cascara sagrada in nature’s Remedy.
Aloe Vera Gel
The fresh mucilagenious gel contained in the parenchymeatous tissue in the center of the leaves of Aloe barbadensis(A.vera) has been used for years in the treatment of burns, abrasions and other skin irritations.
1935 the juice was recommended in treating third degree x-rays burns and more recently has been advocated for its moisturizing and emollient effects.
The plant is valued to cure snake bite, enlarged spleen. It is used as hair tonic
ALLIED DRUG
INDIAN ALOE
It is obtained from Aloe Vera var officialis.It is found on the coasts of Bombay,Gujarat and Madras.It is widely used in cosmetic.