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  Subject Portals: Phytomedicine
   
Aloe ferox
Asphodelaceae

Common names
Bitteraalwyn, Kaapse aalwyn, Bergaalwyn (Afrikaans); bitter aloe, Red Aloe (English); umhlaba ( Sotho); iNhlaba (Zulu); iKhala (Xhosa)
 
Family
Asphodelaceae
 
Description
Aloe - derived from the Greek word for the dried juice of aloe leaves ferox - "fierce" or "war-like" referring to the spiny edged leaves. This aloe is a robust plant with persistent dry leaves on the lower portion of the single stem. The broad, fleshy leaves are dull green or reddish-green, with dark brown spines along the edges and sometimes on the lower surface. The old leaves remain after they have dried, forming a "petticoat" on the stem. Bright red or orange flowers (rarely yellowish or white) appear from May to August. The flowers are carried in a large candelabra-like flower-head.
 
Parts Used
The bitter yellow juice which exudes from just below the surface of the leaf is dried by an age-old method to form a dark brown resin¬ous solid, known commercially as aloe lump or Cape aloes. This product should not be confused with aloe gel, which originates from the inner fleshy part of the leaf. Aloe gel is a watery mixture of pectic sub¬stances, amino acids, minerals, trace elements, or¬ganic acids and various minor compounds. It is used in hair and skin care products.
 
Medicinal Uses
Cape aloes is still an important commercial laxative medicine. The larger part of the annual production is exported, but substantial quan¬tities are marketed and used locally. It is also taken for arthritis. The popular self¬care remedies "Lewensessens" and "Schweden bitters" contain Cape aloes and is found in many pharmacies. A. Ferox and other spe¬cies are used to a great extent in traditional human and livestock medicines. The leaves or roots, boiled in water, are taken as a laxative, but also for arthri¬tis, eczema, conjunctivitis, hypertension and stress. Leaf sap of several species such as A. arborescens and A. greatheadii is applied externally to treat skin irritations, bruises and burns. The dry leaves of A. marlothii are popular in snuff mixtures. Bitters: laxative, tonic; gel: tonic, wound healing. The gel-like flesh from the inside of the leaves is used in cosmetic products and is reported to have wound healing properties
 
Preparation and Dosage
A small crystal of the crude drug, about twice the size of a match head, is taken orally as a laxative. The product should not be used during pregnancy. Half the laxative dose is taken for arthritis. The fresh bitter sap is instilled directly for conjunctivitis and sinusitis.
 
Active Ingredients
The main purgative princi¬ple is the anthrone C-glucoside aloin (=barbaloin). The aloin content in exudate varies between 8,5 and 32%, but 18% is the minimum requirement for export. The wound-healing properties of aloe gel are ascribed to glycoproteins (see Bulbine) and to hy¬drating, insulating and protective effects.
 
Pharmacological Effects
The bitter crystal of the Aloe contains aloin and other anthraquinones. At therapeutic doses, the anthraquinone derivatives act as stimu¬lant laxatives". Aloin is only a prodrug while aloe-¬emodin anthrone, formed in the colon under the influence of bacterial enzymes, is responsible for the laxative action. It is said to increase peristalsis and to affect the absorption of water and electrolytes.

Molecular targets include a chloride channel and less importantly the Na+, K+-ATPase. Anthranoids enhance peristalsis and the secretion of water and in¬hibit its resorption in the colon. Aloe extracts have antimicrobial, antiviral and cytotoxic properties.

The product has a griping and abortifa¬cient effect and should therefore not be used during pregnancy. Laboratory studies indicate that an¬thraquinones may be carcinogenic. Anthraquinone ¬containing laxatives should not be taken for prolonged periods, since K+ homoeostasis will be changed.

 
Distribution
A.Ferox is widely distributed along the eastern parts of South Africa. It is a tall single stemmed aloe which has a wide distribution, ranging over 1000km from the south western Cape through to southern Kwazulu-Natal. It is also found in the south eastern corner of the Free State and southern Lesotho.
 
Bibliography
1. Medicinal plants of South Africa. Ben-Erik van Wyk, Bosch van Oudshoorn, Nigel Gericke. Pretoria: Briza, 1997.
2. Medicinal plants of the world: an illustrated scientific guide to important medicinal plants and their uses. Ben-Erik van Wyk, Michael Wink. Pretoria: Briza, 2004.
 

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