ABSTRACT
Toxic Principle and Mechanism of Action Only the genus Aloe is known to be toxic, and only a few species in the genus have been studied for their toxicity. Aloes contain varying concentrations of anthraquinone glycosides, the most important of which are barbaloin and homonatoloin.2 These bitter tasting compounds that are concentrated in the latex of the new leaves are potent purgatives. The anthracene glycosides are not particularly toxic, but are metabolized by intestinal bacteria into more potent compounds such as aloe-emodin.3 Aloe candelabrum and Aloe ferox have found commercial use as a purgative known as bitter aloes, or cape aloes. The purgative effects of aloes has been attributed to the production of prostaglandins, and increased activity of colonic mucosal adenyl cyclase. This increases mucus secretion and water content of the colon, which stimulates peristalsis and a resulting diarrhea.4 In addition to their purgative effects, aloes also have carcinogenic and abortifacient properties.5,6 The compounds responsible for the supposed beneficial effects of aloe preparations for treating burns and other superficial skin diseases have not been determined. There is evidence that Aloe vera gel when applied topically to second degree burns in guinea pigs actually delayed healing of the burns.7 The cytotoxic effects of low molecular weight compounds in Aloe vera warrant caution in its indiscriminant use.8
