Aloe vera - herbal plant
Aloe vera has a history of use in folk medicine for skin and other disorders which goes back over thousands of years.
Aloe vera has a history of use in folk medicine for skin and other disorders which goes back over thousands of years. More recently, Aloe vera (A.vera) has established a place in homeopathy, herbalism and even conventional medicine. Commercial preparations of A.vera for medicinal and cosmetic use are available.
Aloe is derived from the A.vera plant, a green, succulent, cactus-like plant belonging to the lily family. The substance, A.vera, is derived from thin-walled mucilaginous cells of the inner central zone of the leaf. It is this gel that is thought to have emollient and moisturizing effects and therapeutic properties. A.vera is a complex plant that contains many biologically active substances. One tablespoon of A.vera contains over 75 different chemicals that have biological activity. Therefore it has proved difficult to isolate a single active ingredient, and it has been suggested that there is a synergistic relationship between the constituents . Any substance which can be safely used to treat wounds and inflammatory conditions in the foot would be beneficial to podiatric patient care.
Aloe barbadensis Mill., Aloe ferox Mill. and hybrids with Aloe africana Mill. and Aloe spicata Baker (Liliaceae)
Synonyms and Part Used
Aloe Gel, Aloe vera Tourn. ex L., Aloe vera (L.) Webb
Aloe vera is reported to contain mono- and poly saccharides, tannins, sterols, organic acids, enzymes (including
cyclooxygenase),saponins, vitamins and minerals.
Glucomannan and other polysaccharides containing arabinose, galactose and xylose.
Includes cholesterol, gamolenic acid and arachidonic acid.The polar, non–polar and fatty acid composition has been investigated.
Aloe vera is not used in foods.
Traditionally, aloe vera has been used in ointments and creams to assist the healing of wounds, burns, eczema
Aloe vera refers to the mucilaginous tissue located in the leaf parenchyma of Aloe vera or related Aloe species.However, many documented studies for Aloe vera have utilised homogenised leaf extracts which therefore combine aloe vera with aloes, the laxative preparation obtained from the bitter, yellow juice also found in the leaf.
Gel preparations have been reported to be effective against radiation burns, skin ulcers and peptic ulcers.However, the gel was also found to be ineffective against drug- and stress–induced gastric and peptic ulcers in rats.
Anti–inflammatory activity has been observed in various rat and mouse models that received subcutaneous injections of Aloe vera leaf extract.A positive response was noted in wound–healing, mustard oedema and polymorphonuclear leukocyte infiltration tests, although no activity was demonstrated in the antifibrosis test (cotton pellet granuloma).
Anti–arthritic and anti–inflammatory activity has been documented for a cream containing homogenised Aloe africana leaves, ribonucleic acid, and ascorbic acid, following topical application to rats which had been injected with Mycobacterium butyricum to cause adjuvant arthritis. This model is considered a good
experimental tool for studying rheumatoid arthritis. The cream was found to be active when applied both as a prevention and as a regression treatment. Subsequent work suggested that anthraquinone compounds (anthraquinone, anthracene and anthranilic acid) may be the active components in the aloe leaf mixture.These compounds are, however, constituents of aloes rather than aloe vera . Aloe vera juice (presumably containing the anthraquinones contained in aloe preparation) has been applied directly to open pressure sores to assist in their healing. The aloe vera extract exhibited an anaesthetic reaction, antibacterial action and increased local microcirculation.
Endogenous cyclo oxygenase in Aloe vera has been found to convert endogenous arachidonate to various prostanoids, namely PGE2 (major), TXB2, PGD2, PGF2α, and 6–keto-PGF1bα. The production of these compounds, especially PGE2, has been associated with the beneficial effect of an aloe extract on human bronchial asthma.
Enhancement of phagocytosis in adult bronchial asthma has been attributed to a non–dialysable fraction of the extract, consisting of active components that are a mixture of polysaccharide and protein or glycoprotein.Despite the nature of these proposed active components, it has been proposed that activity of the fraction may
be related to the previous observation that aloe vera synthesises prostaglandins from endogenous arachidonic acid using endogenous cyclooxygenase. In this current study,activity of the aloe vera extract required dark storage at 4–30°C for a period of 3–10 days. These conditions are reported to be favourable for the hydrolysis
of phospholipids, thus releasing arachidonic acid for synthesis of prostanoids. In addition, activity was dependent on patients not having received prior treatment with a corticosteroid.The gel has been reported to be effective in the treatment of mouth ulcers.
Hypoglycaemic activity has been documented for an aloe vera extract, although it is unclear whether this is associated with the true aloe vera gel or aloes extract.
Pregnancy and lactation
The external application of aloe vera gel during pregnancy is not thought to be any cause for concern. However, products stated to contain aloes extracts or aloe vera may well contain gastrointestinal stimulant anthraquinone components that are well recognised as the active constituents in aloes (laxative). As such, ingestion of such
preparations during pregnancy and lactation should be avoided.
Aloe vera is obtained from the mucilaginous tissue in the centre of the Aloe vera leaf and consists mainly of polysaccharides and lipids. It should not be confused with aloes, which is obtained by evaporation of water from the bitter yellow juice that is drained from the leaf. Unlike aloes, aloe vera does not contain any anthraquinone
compounds and does not, therefore, exert any laxative action. Studies have reported an anti–inflammatory and anti–arthritic action for total leaf extracts but the activity seems to be associated with anthraquinone compounds. Hypoglycaemic activity has been reported for aloe vera extract. Aloe vera is a source of gamolenic acid. The literature on burn management with aloe vera gel preparations is confused and further studies are required.