10 Barrantes E, Guinea M. Inhibition of collagenase and metalloproteinases by aloins and aloe gel. Life Sci. January 3, 2003;72(7):843-850.
Source: American Botanical Council
Aloe - Research 2
The laxative effects of Aloe are due primarily to the 1, 8-dihydroxyanthracene glycosides, aloin A and B (formerly designated barbaloin) (23, 24). After oral administration aloin A and B, which are not absorbed in the upper intestine, are hydrolysed in the colon by intestinal bacteria and then reduced to the active metabolites (the main active metabolite is aloe-emodin-9-anthrone) (25, 26), which like senna acts as a stimulant and irritant to the gastrointestinal tract (27). The laxative effect of Aloe is not generally observed before 6 hours after oral administration, and sometimes not until 24 or more hours after.
As with other stimulant laxatives, products containing Aloe should not be used in patients with intestinal obstruction or stenosis, atony, severe dehydration with electrolyte depletion, or chronic constipation (28). Aloe should not be administered to patients with inflammatory intestinal diseases, such as appendicitis, Crohn disease, ulcerative colitis, irritable bowel syndrome, or diverticulitis, or to children under 10 years of age. Aloe should not be used during pregnancy or lactation except under medical supervision after evaluating benefits and risks. Aloe is also contraindicated in patients with cramps, colic, haemorrhoids, nephritis, or any undiagnosed abdominal symptoms such as pain, nausea, or vomiting (28, 29).
Aloe-containing products should be used only if no effect can be obtained through a change of diet or use of bulk-forming products. Stimulant laxative products should not be used when abdominal pain, nausea, or vomiting are present. Rectal bleeding or failure to have a bowel movement within 24 hours after use of a laxative may indicate a serious condition. Chronic use may cause dependence and need for increased dosages, disturbances of water and electrolyte balance (e.g. hypokalaemia), and an atonic colon with impaired function (28).
The use of stimulant laxatives for more than 2 weeks requires medical supervision.
Chronic abuse with diarrhoea and consequent fluid and electrolyte losses (mainly hypokalaemia) may cause albuminuria and haematuria, and may result in cardiac and neuromuscular dysfunction, the latter particularly in the case of concomitant use of cardiac glycosides (digoxin), diuretics, corticosteroids, or liquorice root.
23. Tyler VE, Bradley LR, Robbers JE, eds. Pharmacognosy, 9th ed. Philadelphia, Lea & Febiger, 1988:62–63.
24. Tyler VE. Herbs of choice. New York, Pharmaceutical Products Press, 1994:155–157.
25. Che QM et al. Isolation of human intestinal bacteria capable of transforming barbaloin to aloe-emodin anthrone. Planta medica, 1991, 57:15–19.
26. Aloe caoensis, Cape aloes: proposal for the summary of product characteristics. Elburg, Netherlands, European Scientific Committee of Phytotherapy, 1995.
27. Reynolds JEF, ed. Martindale, the extra pharmacopoeia, 30th ed. London, Pharmaceutical Press, 1993:903.
28. Goodman and Gilman's the pharmacological basis of therapeutics, 8th ed. New York, McGraw Hill, 1990.
29. Bisset NG. Sennae folium. In: Max Wichtl's herbal drugs & phytopharmaceuticals. Boca Raton, FL, CRC Press, 1994:463–469.
Source: WHO Monographs Vol 1, 1999 -2010