Aloins

Aloins are a group of bitter yellow glycosides found in the latex of certain Aloe species, most notably Aloe vera. The two principal constituents are aloin A (barbaloin) and aloin B (isobarbaloin). They belong to the class of anthraquinone glycosides, with the aglycone aloe-emodin linked to a glucose moiety. The two forms differ in stereochemistry around their sugar attachment.

Aloins occur predominantly in the yellow latex that lies between the outer rind and the fleshy inner leaf. This latex is distinct from the mucilaginous gel that is commonly used in cosmetics and skin products, which generally contains little or no aloin.

Historically, aloin has been used as a stimulant laxative. It remains present in some over-the-counter laxatives and traditional remedies, though many modern aloe products intended for internal use are processed to reduce or remove aloin content. Some manufacturers market “aloin-free” aloe preparations for internal use, while keeping aloe gel products for topical applications.

Safety and regulation around aloin-containing products vary by jurisdiction. Ingested aloins can cause abdominal cramping, diarrhea, and electrolyte disturbances, and chronic high intake has raised safety concerns. Regulatory agencies have increasingly scrutinized aloe latex products, and the International Agency for Research on Cancer has assessed aloe-derived products with latex content as potentially carcinogenic in certain contexts, leading to labeling and use restrictions in some regions. As a result, many contemporary aloe preparations distinguish between latex-derived aloins and aloe gel components.

See also: Aloe vera, Anthraquinones, Laxatives.