Aloe.(Drug overview)

Aloe barbadensis/capensis/vera

TRADE NAMES

Aloe Vera (available from numerous manufacturers), Herbal Sure Aloe Vera, Aloe Vera Mild Stimulant Laxative, Aloe 99 Gel, Sundance Aloe Vera Gel, Chantal Aloe Vera Cream, Palmers Aloe Vera Formula Cream, Aloe Vera Super Strength, Herbal Sure Aloe Vera

DESCRIPTION

Medicinal Parts: The medicinal part of the plant is dried juice of the leaves.

Flower and Fruit: The inflorescence is forked once or twice and is 60 to 90 cm high. The raceme is dense, cylindrical and narrows toward the top. The terminal raceme is up to 40 cm high while the lower ones are somewhat shorter. The bracts are almost white, and the flowers are yellow, orange or red, and are 3 cm long.

Leaves, Stem, and Root: The lilylike succulent-leafed rosette shrub has a 25-cm stem or none at all. The stem has about 25 leaves in an upright dense rosette. The lanceolate leaf is thick and fleshy, 40 to 50 cm long and 6 to 7 cm wide at the base. The upper surface is concave, gray-green, often with a reddish tinge, which sometimes appears in patches in the young plants. The leaf margin has a pale pink edge and 2 mm long pale teeth.

Habitat: Aloe is thought to have originated in the Sudan and the Arabian Peninsula. Today the species is cultivated and found in the wild in northern Africa, the Near East, Asia, and in the southern Mediterranean region. The plant is cultivated in subtropical regions of the United States and Mexico, and on the Dutch Antilles, as well as coastal regions of Venezuela.

Production: Curacao Aloe consists of the dried latex of the leaves of Aloe barbadensis (syn. Aloe vera), as well as its preparations. Aloe is harvested from August until October. The juice is dried using various methods.

Not to be Confused With: Confusion sometimes arises with Agave americana, known as American Aloe, which is not a true Aloe.

ACTIONS AND PHARMACOLOGY

COMPOUNDS: ALOE BARBADENSIS

Anthracene derivatives: particularly anthrone-10-C-glycosyls, including aloin A, aloin B, 7-hydroxyaloins A and B, and 1,8-dihydroxy ions, including Aloe-emodin, and 6'cinnamic acid esters of these compounds

2-alkylchromones: including Aloe resins B, C and D

Flavonoids

COMPOUNDS: ALOE CAPENSIS

Anthracene derivatives: particularly anthrone-10-C-glycosyls, including aloin A, aloin B, 5-hydroxyaloin, and 1,8-dihydroxy anthraquinones, including Aloe-emodin, and mixed anthrone-C- and O-glycosides, including aloinosides A and B

2-alkylchromones: including Aloe resins A, B, C and D

Flavonoids

EFFECTS

Antibacterial/Antiviral Effects: Aloe-emodin exerts dose-dependent growth inhibition of Heliobacter pylori through inhibition of arylamine N-acetyltransferase (NAT) activity (Wang, 1998). Aloe-emodin has shown antibacterial effects on four strains of methicillin-resistant Staphylococcus aureus (Hatano, 1999). Aloe emodin inactivates enveloped viruses and is directly viracidal to herpes simplex virus type 1 and type 2, varicella-zoster virus, pseudorabies virus, and influenza virus (Sydiskis, 1991).

Anti-inflammatory effects: The anti-inflammatory effect of the Aloe gel may be due to the salicylates, inactivation of bradykinin (via carboxypeptidases), and inhibition of histamine formation (Briggs, 1995; Natow, 1986). It appears that various nonspecified components in the gel reduce the oxidation of arachidonic acid, thereby reducing prostaglandin synthesis and inflammation (Davis et al, 1987; Pennys, 1982).

Antineoplastic Effects: Emodin suppresses tyrosine kinase activity of HER-2/neu-encoded p185neu receptor tyrosine kinase resulting in antineoplastic effects. This is beneficial in controlling HER-2/neu overexpressing cancer cells (Zhang, 1998).

Laxative (Cathartic) Effects: Anthraquinones such as Aloe are colonic-specific stimulant laxatives that have a direct action on intestinal mucosa, increasing the rate of colonic motility, enhancing colonic transit time, and inhibiting water and electrolyte secretion (Klinik et al, 1993; Godding, 1988). In addition, the laxative effect is due to irritation and stimulation of the colon. Other ingredients include Aloe-emodin, Aloesin, Aloetic acid, anthracene, anthranol, barbaloin, beta-or isobarbaloin, chrysophanic acid, cinnamic acid ester, emodin, an ethereal oil, resins (resistannol), and saponins (Shelton, 1991; Holdsworth, 1971; McCarthy & Haynes, 1967). There is some evidence that endogenous nitric oxide modulates the diarrhea effect of Aloe. Studies demonstrate a laxative effect 9 hours after ingestion (Izzo, 1999).

Anthraquinones may also have stool softening properties and do not disrupt the usual pattern of defecation (Gilman et al, 1990; Godding, 1988). The onset of action may be in 6 to 12 hours, or delayed for up to 24 hours (Koch, 1993; Cohen, 1992). Aloe vera latex, the pericyclic cells of the leaf produce a bitter yellow latex which is dried to give a dark brown solid material called "ALOEs" in many older pharmacy texts. This material is a strong cathartic containing various anthraquinones usually designated as aloin, which is primarily 1,8-dihyroxy-3-(hydroymethyl)-p,10-anthracenedione (Briggs, 1995).

A partial purification (via ethanolic and aqueous extracts) of Aloe vera leaves was strongly antibacterial and inhibited the growth of Bacillus subtilis. The action of the antibiotic substance was thought to be inhibition of nucleic acid synthesis and subsequent protein synthesis (Levin et al, 1988).

The sugar and polysaccharide content of the Aloe gel may be …