ALoes is a drug of great antiquity, for we find it mentioned by Dioscorides (50 A.D.). Till modern times, the source of the drug was the island of Socotra, but at present it is imported from various parts of the world. The chief varieties are distinguished by colour, smell, and fracture, and in the London market are: Socotrine aloes—derived from the Aloë perryi, not from the Aloë socotrina, which was till recently believed to be the source of the drug; Barbadoes aloes; Cape aloes; and Natal aloes.
These various forms of the drug are derived from several species of aloe, but they all agree in possessing a bitter taste, and having powerful purgative properties. Active principles, similar in nature but differing in composition, are found in the three chief varieties. These are Socaloin, , found in Socotrine aloes; Nataloin, , found in Natal aloes; Barbaloin, , found in Barbadoes aloes.
When employed in small doses as extract, tincture, pills, or otherwise, aloes exerts a tonic, and in larger doses, a cathartic action.