phytotherapy

Aloe vera - Therapeutic indications

By Dr. Rita Fabbri

The pharmacological activity of Aloe vera is very complex precisely because the chemical constituents of the plant are very numerous and, as we have already said, the therapeutic effects of Aloe are the result of the synergistic interaction of the active ingredients with receptive molecules of the organism human.

Even more or less recent scientific publications and clinical studies are manifold.

We can thus summarize the therapeutic properties of Aloe vera.

Antioxidant and anti-aging activity

The minerals (especially manganese, copper, selenium) contained in Aloe juice are constituents of the superoxide dismutase and glutathione peroxidase enzymes, two important antioxidant and cellular anti-aging agents. The non-essential amino acid proline is a constituent part of collagen. Saponins promote better and faster cell exfoliation.

Vitamins (in particular vitamin C, E, B2, B6) and the non-essential amino acid, cysteine, are powerful antioxidants able to combat cellular damage caused by free radicals and in particular by superoxide anion.

In particular, cysteine ​​and B group vitamins are able to bind to toxic molecules deriving from pathological processes to form inert compounds.

It is now known that oxidative stress is favored by chemical, physical, biological, mental and nutritional factors; accelerates the physiological cellular aging process and is responsible for several degenerative diseases. It is then clear what importance the constant intake of Aloe juice in the diet has: the recommended daily dose should not be less than 100 ml of pure juice (1-4).

Healing and restorative activity

It is an activity directly related to the anti-inflammatory one. Aloe vera stimulates the formation of fibroblasts, precursors of epithelial cells, and of connective tissue. In this process of repair and formation of epithelial tissue, polysaccharides certainly intervene as primary factors; the second factors seem to be plant hormones, gibberellins and auxins (5-6).

The most recent studies are focused on demonstrating the ability of Aloe gel to prevent progressive dermal ischemia caused by radiation and burns, and the efficacy of the gel in the treatment of diabetic ulcers, chronic ulcers and Psoriasis vulgaris.

The following are particularly interesting:

  • Twenty albino rats were exposed to β-rays and the injured areas of each animal were divided into quadrants and a different treatment was applied to each quadrant. Fresh leaves of Aloe vera, a commercial Aloe vera ointment, application of bandages with dry gauze and a control without treatment. Both the fresh leaves and the Aloe vera ointment led to significant improvements: after two months the areas treated with Aloe vera had completely healed, while the other two areas, after 4 months, had not yet healed (7).
  • Experimentally, the Aloe gel was compared with lodoxamide, lazaroid and Carrington gel, used to prevent the loss of tissue in wounds due to their ability to inhibit local production of TxA2; in burns the Aloe gel was comparable with lodoxamide and lazaroid, with a tissue survival of 82-85% compared to the Carrington control and gel. From the complete analysis of the results we can conclude that Aloe not only acts as an inhibitor of TxA2 but contributes to the maintenance of homeostasis of vascular endothelium and surrounding tissue (8).
  • Experimental studies on rats and mice suggest that Aloe vera is effective both for topical use and for internal use, in the treatment of diabetic ulcers of the lower limbs. In addition to facilitating wound healing (9), Aloe vera also has a hypoglycemic effect both in healthy mice and in those with induced alloxan diabetes (10), through a mechanism of action not entirely known, perhaps mediated by the stimulation of synthesis and / or release of insulin from Langerhans β cells.
  • On three patients with chronic leg ulcers, Aloe vera gel was applied with gauze bandages: the gel induced a rapid reduction in the extent of the ulcers in all three patients, and healing in two (11).
  • In a double-blind study, the efficacy and tolerability of a 0.5% Aloe vera gel in a hydrophilic cream in the treatment of patients with Psoriasis vulgaris was evaluated. Sixty patients (36 males and 24 females) aged between 18 and 50 years with light or moderate psoriasis plaques were included in the study and randomly distributed in two groups. Patients were provided with a pack of 100g cream containing placebo or active ingredients (0.5% Aloe vera gel); they had to apply the product (without occlusion) 3 times a day, 5 consecutive days per week, for no more than 4 weeks. Patients were followed up on a monthly basis for 12 months. The treatment showed no side effects. At the end of the study, the Aloe vera treatment improved the symptomatology of 25 patients out of 30 (83.3%), while the placebo improved the condition to only 2 patients out of 30. This suggests that topical application of a cream containing Aloe vera gel can be considered a safe and valid treatment for patients with psoriasis (12).

Most Aloe vera studies have been conducted on different animals, in various experimental models of scarring and inflammation. Although limited, research on wound healing in humans is promising and encouraging results have also been reported for acne and seborrhea, and in pediatric aphthous stomatitis, where the efficacy of a new adhesive patch has been evaluated based on Aloe vera: after a period of treatment, in 77% of cases the problem has been solved and in the remaining 23% there is a notable reduction in discomfort (13).

Antibacterial and antifungal activity

The antimicrobial effects of Aloe vera are comparable to those of silver sulfadiazine, an antibiotic from the sulfamidic family which is very often used topically to prevent skin infections in burn patients. It has been shown that the bactericidal action of Aloe is directly proportional to its concentration; in particular, 60% extracts are active against Pseudomonas aeruginosa, Klebsiella pneumoniae, Streptococcus pyogenes ; 70% extracts on Staphylococcus aureus, 80% extracts on Escherichia coli and 90% extracts on Candida albicans . It seems to have a bactericidal action also towards Mycobacterium tubercolosis and Bacillus subtilis (14-15).

We only mention the fact that some anthraquinone glycosides contained in Aloe vera juice, the aloins, also exhibit antibiotic properties and that cinnamic acid has a good antiseptic and germicidal action.

Antiviral activity

Acemannan in particular, polymeric sugar isolated in Aloe vera juice, has significant antiviral activity against various viruses such as HIV-1 and Paramyxovirus (the measles virus). In vitro studies have shown that acemannan, in combination with sub-optimal concentrations of azidothymidine (AZT or the antiviral drug used for the treatment of AIDS) or aciclovir, acts synergistically by inhibiting the replication of HIV and Herpes simplex ( 16). On the basis of these studies, it is hypothesized that acemannan can be used to lower the concentration of AZT in the treatment of early stages of AIDS and thus reduce the serious side effects caused by the drug (17). To confirm, we can recall a study where Aloe vera juice was administered, along with essential fatty acids, amino acids, multivitamin and multimineral supplements, in the treatment of 29 patients - 15 with AIDS, 12 with an AIDS-related syndrome, 2 HIV serum-positive - who continued the prescribed therapy including AZT. After 180 days, all patients had clinical improvement and AZT-induced anemia was decreased (18).

Ahemannan has not had significant effects in patients with full-blown AIDS (19).

(20).

Immunomodulatory activity

Ahemannan, contained in the Aloe vera gel, is a powerful stimulant of the immune system. It works by stimulating the activity of macrophages and with it the production of cytokines by the macrophages themselves; promotes the release of substances that enhance the immune system (such as nitric oxide or nitrogen monoxide); causes cellular morphological changes in particular intervenes in the expression of surface antigens. Ahemannan is able to enhance the activity of T cells and to increase the production of interferon even if these actions could be related to the stimulation of macrophage activity. The immunostimulatory activity of acemannan was dose-dependent (21-22).

Animal studies have shown promising results in case of induced sarcomas and spontaneous tumors (23-24). It has also been noted that Aloe juice enhances the antitumor effect of 5-fluorouracil and cyclophosphamide, two important drugs of combined chemotherapy (25).

Anti-inflammatory and analgesic activity

Aloe vera has a significant anti-inflammatory and pain-relieving action, for both topical and oral application, and its anti-inflammatory activity is mediated by the inhibition of the production of prostaglandins by the enzyme bradichinasi; of histamine by magnesium lactate; and of leukotrienes by particular glycoproteins such as haloctina A.

The enzyme bradichinasi contained in the Aloe, is capable of hydrolysing bradykinin, an endogenous substance with a polypeptide structure, responsible for numerous characteristic events of the inflammatory process: vasodilation, increased vascular permeability, contracturing action on the musculature, sensation of heat, pain, redness, swelling; we can therefore say that Aloe vera is an excellent anti-inflammatory and pain-relieving remedy, thanks to its intense anti-bradykinin activity (26-29).

The magnesium lactate present in Aloe is capable of inhibiting the enzyme involved in the production of histamine, a vasoactive substance involved in the inflammatory process.

Also the halocressin A isolated in the Aloe, has shown to have good anti-inflammatory properties in the carrageenan-induced edema in the rat: it reduces the swelling of the treated paw, the action is rapid (about three hours after the injection), dose dependent and free of side effects (30). A similar result in the experimental model of arthritis induced in the rat.

Another component of Aloe vera with good anti-inflammatory properties is C-glycosyl-chromone: applied topically, the compound has anti-inflammatory activity equivalent to that of hydrocortisone at the same dose and, unlike the drug, does not cause side effects ( 31).

arthrosis pathologies (32).

Gastrointestinal tonic and gastroprotective activity

Aloe vera juice can resolve the most common gastrointestinal disorders such as abdominal spasms, heartburn, pain and swelling; Aloe gel normalizes intestinal secretions, influences the intestinal bacterial flora, stabilizes the pH in the stomach and intestine, improves the functionality of the pancreas and in the colon limits the proliferation of pathogens reducing the putrefactive phenomena.

Aloe gel can improve some forms of gastritis (peptic ulcers) and intestinal inflammation (irritable bowel); the effectiveness of the gel is to be attributed to its cicatrizing, anti-inflammatory, analgesic action and the ability to coat and protect the stomach walls.

The use of Aloe vera juice as a gastrointestinal tonic is very frequent even if there is little scientific evidence to support it. The following is certainly significant:

  • In a study of ten subjects (five men and five women) the effects of Aloe vera juice on urinary indacane, on gastrointestinal pH, on coproculture and on the specific weight of faeces were evaluated. 170g of Aloe vera juice was given three times a day for a week. The urinary indane reflects the degree of malabsorption of food proteins, therefore high levels of indane in urine are therefore an indication of "protein putrefaction". In all subjects the urinary indacane decreased by one unit and this denotes a better assimilation of the proteins that is a reduction of the bacterial putrefaction.

    The gastric pH in all patients increased on average by 1.88 units and this result confirms the hypothesis that Aloe vera is able to inhibit the secretion of hydrochloric acid; it also seems capable of slowing gastric emptying thus facilitating digestion.

    After a week of treatment, in six out of ten subjects, the results of the coproculture were profoundly modified; this means that Aloe vera juice could have an antibacterial action in particular against Candida albicans; a reduction in yeast colonies occurred in the four patients with positive culture of Candida albicans.

    After a week of treatment, the specific gravity of the stools was reduced and this shows an improvement in water retention; however, none of the subjects complained of diarrhea or loose stools while taking Aloe juice (33).

Numerous scientific works demonstrate the gastroprotective activity of Aloe suco, The following is particularly interesting:

  • Twelve patients with established X-ray duodenal ulcers were given one tablespoon of Aloe vera gel emulsion in mineral oil once a day. After one year, all patients had complete recovery and no recurrence (34).

On the basis of this and other experimental evidences, we can affirm that Aloe vera gel inactivates pepsin in a reversible way: in fasting pepsin is inhibited by the gel while in the presence of food pepsin is released and intervenes in digestion; the Aloe gel inhibits the release of hydrochloric acid by interfering in the binding of histamine to the parietal cells; Aloe gel is an excellent soothing and emollient of gastrointestinal mucosa and prevents irritants from reaching the ulcers. These activities are attributable to the polysaccharide component, glycoprotein, enzymatic (especially the enzyme bradichinasi), to plant hormones (gibberellins and auxins) and to dehydroabietic acid derivatives recently isolated in Aloe vera gel and capable of inhibiting the secretion of hydrochloric acid (35).

Anti-asthmatic activity

The oral administration of Aloe vera extract for 6 months gave good results in the treatment of asthma (36). Only in the case of corticosteroid-dependent patients, the Aloe extract was not active. It is thought that the anti-asthmatic action is related to a protective and anti-inflammatory activity and to the strengthening of the immune system.

Purifying and laxative activity

Aloe vera juice performs its detoxifying action in the gastrointestinal tract which is a district particularly suited to the accumulation of toxins.

The purifying activity is mainly linked to polysaccharides, capable, thanks to the particular composition and viscous consistency, of binding and eliminating the toxic substances produced during metabolic processes, thus reducing the contact time of the slag with the mucous membranes.

Aloin, contained in latex (latex derived from the peel of the leaf), gives Aloe real laxative activity. In small doses, aloe acts as a digestive system tonic, giving tone to the intestinal muscles. At a higher dosage it becomes a strong laxative that acts on the large intestine where it stimulates the secretions of the colon and promotes intestinal peristalsis. Aloin has been the most widely used anthraquinone laxative for many years (37); often causes painful contractions and for this reason currently other anthraquinones are used such as cascara and senna (see appendix "Pharmacological notes on anthraquinones").