Aloe Vera – Basic Review

Aloe barbadensis/capensis/vera
TRADE NAMES
Aloe Vera Herbal Products are available in markets: Herbal Sure Aloe Vera, Aloe Vera Mild Stimulant Laxative, Aloe99 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.
Arabian Peninsula and Sudan I thought as place where the aloevera was originated. Today, the species has been cultivating in many country and can be found in the wild in Mediterranean, Asia, Near East and Northern Africa

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 lily-like succulent-leafed rosette shrub either does not have a stem or has a 25 cm stem. 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, graygreen,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 an throne- 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
Laxative Effects
Aloe anthranoids such as 1,8-dihydroxy-anthracene derivatives exert a laxative effect. The laxative action is due to g* anti-absorption osmotic properties. The compounds induce active secretion of electrolytes and water in the lumen of the bowel. Absorption of electrolytes and water from the colon is inhibited resulting in a volume increase. The volume increase of the bowel content leads to an increase in pressure and stimulates intestinal peristalsis. 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).

Antibacterial/Antiviral Effects
Aloe-emodin exerts dose-dependent growth inhibition of H. 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,<(�P pseiidorabies virus, and influenza virus (Sydiskis. 1991).

Antineoplastic Effects
Emodin suppresses tyrosine kinase activity of HER-2/neuencoded pl85neu receptor tyrosine kinase resulting in antineoplastic effects. This is beneficial in controlling HER- 2/neu overexpressing cancer cells (Zhang, 1998).

Effects of topical Aloe plants
Aloe vera depresses action potential generation and conduction at neuromuscular junction processes which result in analgesic and anti-inflammatory effects (Friedman, 1999). Ultraviolet radiation (UV) suppresses delayed type hypersensitivity (DTH) by altering the function of immune cells in the skin and causing the release of immunoregulatory cytokines. Extracts of crude Aloe barbadensis gel inhibits this photosuppression by preventing suppression of DTH responses and reducing the amount of keratinocyte derived immunosuppressive cytokines (IL-2) (Byeon, 1998; Strickland, 1999). Aloe vera gel contains small molecular modulators 4^ that prevent UVB-induced immune suppression in the skin. The immunomodulators restore the UVB-induced damages on epidermal Langerham cells (Lee, 1999). Aloe vera increases collagen content of the granulation tissue and its degree of crosslinking to contribute to wound healing (Chithra, 1998). Aloe vera acts as a modulatory system toward wounds with anti-inflammatory effects (Davis,1991). The use of Aloe vera has been associated with a delaying wound healing compared to standard treatment (Schmidt,1991). Aloe vera gel exerts anti-inflammatory activity through its inhibitory action on the arachidonic acid pathway via cyclooxygenase (Vazquez, 1996). Due to its anti-thromboxane effects, Aloe vera decreases the morbidity of progressive dermal ischemia in frostbite (Heggers, 1987). Aloe vera contains a carboxypeptidase that inactivates bradykinin, salicylates, and a substance that inhibits thromboxane formation (Fujita, 1976; Klein, 1988).

CLINICAL TRIALS
Psoriasis
A double-blind, placebo-controlled study was conducted to evaluate the clinical efficacy and tolerability of topical Aloe vera extract 0.5% (in hydrophilic base) in patients with psoriasis vulgaris. There were 60 patients with slight to moderate chronic plaque-type psoriasis determined by the Psoriasis Area and Severity Score (PASI). The extract was applied topically three times daily for 5 consecutive days per week with a maximum of 4 weeks active treatment. The study period was for 16 weeks with monthly check-ups for a period of 12 months. Aloe vera extract cream had a significantly higher cure rate and clearing of psoriatic plaques compared to placebo. The PASI score was also decreased in the Aloe treatment group compared to placebo. The Aloe-treatment group had no adverse drug related symptoms and the drug was well tolerated (Syed, 1996).

Radiation-Induced Skin Toxicity
A phase III, double-blind, placebo-controlled study evaluated Aloe vera gel for use as a prophylactic agent for radiation-induced skin toxicity. A total of 194 women receiving breast or chest wall irradiation were included in the study. Skin dermatitis was scored weekly during the trial by patients and by health care providers. Aloe vera gel did not protect against radiation therapy-induced dermatitis (Williams,
1996).

INDICATIONS AND USAGE
ALOE BARBADENSIS AND CAPENSIS
Approved by Commission E:
� Constipation
ALOE BARBADENSIS
Unproven Uses: The drug is used for evacuation relief in the presence of anal fissures after recto-anal operations. In European folk medicine the drug is employed for its ability to influence digestion.
Chinese Medicine: The most common use in Chinese medicine is for treatment of fungal diseases.
Indian Medicine: Uses in Indian medicine include stomach tumors, constipation, colic, skin diseases, amenorrhea, worm infestation, and infections.
ALOE CAPENSIS
Unproven Uses: Aloe capensis has been used as a stool softener in the presence of anal fissures, hemorrhoids, and after recto-anal operations. The fresh juice is used for eye inflammations and for syphillis in South Africa.
Homeopathic Uses: The herb is used for gastrointestinal disorders, hemorrhoids, and constipation.

CONTRAINDICATIONS
Aloe is contraindicated in cases of intestinal obstruction, acutely inflamed intestinal diseases (e.g., Crohn’s disease, ulcerative colitis), appendicitis and abdominal pain of unknown origin.

PRECAUTIONS AND ADVERSE REACTIONS
General: If cramping of the gastrointestinal tract after single dosing occurs, the dosage should be reduced. Spasmodic gastrointestinal complaints are a side effect to the drug’s purgative effect. Heart arrhythmias, nephropathies, edema and accelerated bone deterioration may occur in rare cases. Prolonged use of Aloe may lead to pigmentation in the intestinal mucosa (pseudomelanosis coli), a harmless side effect, which usually reverses upon discontinuation of the drug. Long-term use can also lead to albuminuria and hematuria.

Hypersensitivity: Hypersensitivity, manifested by generalized nummular eczematous and papular dermatitis, have been reported after long-term use of oral and topical Aloe preparations (Morrow, 1980).

Loss of Electrolytes: Long-term use can cause loss of electrolytes, in particular potassium. The loss of potassium can result in hyperaldosteronism, inhibition of intestinal motility and enhancement of the effect of cardioactive medications.

Malignancy: Prolonged use of anthracene drugs increases the relative risk of colon carcinoma (Siegers, 1993). Recent studies fail to demonstrate a connection between the administration of anthracene drugs and frequency of carcinomas in the colon (Schorkhuber; 1998). Low molecular weight compounds found in Aloe vera gel are cytotoxic (Avila, 1997). The component 1,8-dihydroxyanthraquinone inhibits the catalytic activity of topoisomerase II resulting in genotoxicity and mutagenicity (Mueller, 1999).

Tissue Damage: Chronic treatment with high doses of Aloe reduces vasoactive intestinal peptide and somatostatin levels, which may damage enteric nervous tissue (Tzavella, 1995).

Drug Interactions:
Cardiac glycosides and antiarrhythmic drug�Chronic use of Aloe can lead to potassium loss, which can increase the actions of cardiac glycosides and antiarrhythmic drugs. Thiazide diuretics, loop diuretics, licorice and corticosteroids� There is an increase in the possibility of potassium deficiency when Aloe is used along with these agents.

Pregnancy: Aloe should not be used during pregnancy.
Pediatric Use: Aloe should not be prescribed to children under 12 years of age.

DOSAGE
Mode of Administration: Due to the side effects of the drug, it is rarely used and is not recommended. Aloe powder, aqueous- and aqueous-alcoholic extracts in powdered or liquid form are available for oral use.
How Supplied:
Capsule�250 mg, 470 mg
Cream Gel�99%, 72%
Softgel�1000 mg
Preparation: A stabilized aloe extract is prepared with hot water. The extract will have a content of 19% to 21% aloin.
Daily Dosage: The recommended daily dosage is 20 to 30 mg hydroxyanthracene derivatives/day, calculated as anhydrous aloin. The recommended single dosage is 0.05 g q powder from Aloe barbadensis or 0.05 to 0.2 g aloe powder of Aloe capensis in the evening. Aloe capensis can be given as a single dose of 0.1 g in the evening.
Homeopathic Dosage: For Aloe capensis, administer 5 drops, 1 tablet, 10 globules, or parenterally 1-2 ml three times daily (HAB1).
Note: The smallest dosage needed to maintain a soft stool should be used. Stimulating laxatives must not be used over an extended period of time (1 to 2 weeks) without medical advice.
Storage: Aloe should be protected from light and moisture.

Article Source : PDR for Herbal Medicines

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