Aloe Vera


Clinical Studies
References


Aloe Vera gel may be beneficial in inflammation, skin disorders, constipation, arthritis, fever, anesthesia, itching, as a general tonic, antiseptic and moisturizer and may be beneficial in gastroduodenal ulcers, diabetes and asthma.

Aloe gel is the clear, jelly-like substance that is obtained from the thin-walled, sticky cells of the inner portion of the leaf. It is of benefit as an immunity booster, in anti-aging, cancer and viral infection.


Published Clinical Studies
Aloe Vera


Aloe vera leaf gel: a review update.

Reynolds T, Dweck AC.

Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond, Surrey, UK.

Research since the 1986 review has largely upheld the therapeutic claims made in the earlier papers and indeed extended them into other areas. Treatment of inflammation is still the key effect for most types of healing but it is now realized that this is a complex process and that many of its constituent processes may be addressed in different ways by different gel components. A common theme running though much recent research is the immunomodulatory properties of the gel polysaccharides, especially the acetylated mannans from Aloe vera, which are now a proprietary substance covered by many patents. There have also been, however, persistent reports of active glycoprotein fractions from both Aloe vera and Aloe arborescens. There are also cautionary investigations warning of possible allergic effects on some patients. Reports also describe antidiabetic, anticancer and antibiotic activities, so we may expect to see a widening use of aloe gel. Several reputable suppliers produce a stabilized aloe gel for use as itself or in formulations and there may be moves towards isolating and eventually providing verified active ingredients in dosable quantities

Publication Types:

  • Review
  • Review Literature


PMID: 10624859 [PubMed - indexed for MEDLINE]

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Modified Aloe barbadensis polysaccharide with immunoregulatory activity.

Qiu Z, Jones K, Wylie M, Jia Q, Orndorff S.

Department of Drug Discovery and Screening, Univera Pharmaceuticals, Inc., Broomfield, CO, USA. jqiu@upi1.com

Aloe barbadensis polysaccharide was partially digested with cellulase and further purified by dialysis, stepwise ethanol precipitation, and size exclusion chromatography. Crude modified Aloe polysaccharide (MAP) activated macrophage cells and stimulated fibroblast growth. Under the same conditions, native Aloe barbadensis gel had no effect on macrophage activation. MAP prevented ultraviolet B (UVB) irradiation-induced immune suppression as determined by contact hypersensitivity (CHS) response in C3H/HeN mice. This in vivo activity was correlated with the activity of MAP to inhibit UVB irradiation-induced tumor necrosis factor alpha (TNF-alpha) release from human epidermoid carcinoma cells (KB cells). MAP with an average molecular weight of 80,000 Dalton (Da) contained mannose, galactose, and glucose in a ratio of 40:1.4:1.0. MAP was likely a linear, highly acetylated molecule.

PMID: 10763590 [PubMed - indexed for MEDLINE]

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Evaluation of antioxidant potential of aloe vera (Aloe barbadensis miller) extracts.

Hu Y, Xu J, Hu Q.

College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, PRC.

The polysaccharide and flavonoid concentrations of two-, three-, and four-year-old Aloe vera were determined, and their antioxidant activities were evaluated compared to BHT and alpha-tocopherol by the DPPH radical scavenging method and the linoleic acid system at 100 microg of soluble solids per mL of ethanol. The results showed that three-year-old Aloe vera contained significantly higher levels of polysaccharides and flavonoids than two- and four-year-old Aloe vera, and no significant differences in flavonoid levels were found between three- and four-year-old Aloe vera. All the aloe extracts showed significant antioxidant activity. The antioxidant activity of Aloe vera extracts and reference compounds followed the order: three-year-old Aloe vera > BHT > four-year-old Aloe vera > alpha-tocopherol > two-year-old Aloe vera. The three-year-old extract exhibited the strongest radical scavenging activity of 72.19%, which is significantly higher than that of BHT at 70.52% and alpha-tocopherol at 65.20%. These data suggest that the growth stage plays a vital role in the composition and antioxidant activity of Aloe vera.

PMID: 14664546 [PubMed - in process]

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In vitro chemopreventive effects of plant polysaccharides (Aloe barbadensis miller, Lentinus edodes, Ganoderma lucidum and Coriolus versicolor).

Kim HS, Kacew S, Lee BM.

Division of Toxicology, College of Pharmacy, Sungkyunkwan University, Changan-ku, Chunchun-dong, Kyunggi-do, Suwon 440-746, Korea.

A plant polysaccharide, Aloe gel extract, was reported to have an inhibitory effect on benzo[a]pyrene (B[a]P)-DNA adduct formation in vitro and in vivo. Hence, chemopreventive effects of plant polysaccharides [Aloe barbadensis Miller (APS), Lentinus edodes (LPS), Ganoderma lucidum (GPS) and Coriolus versicolor (CPS)] were compared using in vitro short-term screening methods associated with both initiation and promotion processes in carcinogenesis. In B[a]P-DNA adduct formation, APS (180 micrograms/ml) was the most effective in inhibition of B[a]P binding to DNA in mouse liver cells. Oxidative DNA damage (by 8-hydroxydeoxyguanosine) was significantly decreased by APS (180 micrograms/ml) and CPS (180 micrograms/ml). In induction of glutathione S-transferase activity, GPS was found to be the most effective among plant polysaccharides. In screening anti-tumor promoting effects, APS (180 micrograms/ml) significantly inhibited phorbol myristic acetate (PMA)-induced ornithine decarboxylase activity in Balb/3T3 cells. In addition, APS significantly inhibited PMA-induced tyrosine kinase activity in human leukemic cells. APS and CPS significantly inhibited superoxide anion formation. These results suggest that some plant polysaccharides produced both anti-genotoxic and anti-tumor promoting activities in in vitro models and, therefore, might be considered as potential agents for cancer chemoprevention.

PMID: 10426820 [PubMed - indexed for MEDLINE]

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Acemannan purified from Aloe vera induces phenotypic and functional maturation of immature dendritic cells.
Lee JK, Lee MK, Yun YP, Kim Y, Kim JS, Kim YS, Kim K, Han SS, Lee CK.

College of Pharmacy, Chungbuk National University, Cheongju 361-763, South Korea.

Acemannan, a major carbohydrate fraction of Aloe vera gel, has been known to have antiviral and antitumoral activities in vivo through activation of immune responses. The present study was set out to define the immunomodulatory activity of acemannan on dendritic cells (DCs), which are the most important accessory cells for the initiation of primary immune responses. Immature DCs were generated from mouse bone marrow (BM) cells by culturing in a medium supplemented with GM-CSF and IL-4, and then stimulated with acemannan, sulfated acemannan, and LPS, respectively. The resultant DCs were examined for phenotypic and functional properties. Phenotypic analysis for the expression of class II MHC molecules and major co-stimulatory molecules such as B7-1, B7-2, CD40 and CD54 confirmed that acemannan could induce maturation of immature DCs. Functional maturation of immature DCs was supported by increased allogeneic mixed lymphocyte reaction (MLR) and IL-12 production. The differentiation-inducing activity of acemannan was almost completely abolished by chemical sulfation. Based on these results, we propose that the adjuvant activity of acemannan is at least in part due to its capacity to promote differentiation of immature DCs.

PMID: 11460308 [PubMed - indexed for MEDLINE]

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Characterization of Aloeride, a new high-molecular-weight polysaccharide from Aloe vera with potent immunostimulatory activity.

Pugh N, Ross SA, ElSohly MA, Pasco DS.

Department of Pharmacognosy, National Center for Natural Products Research, University of Mississippi, University, Mississippi 38677, USA.

We have characterized a new immunostimulatory polysaccharide called Aloeride from commercial aloe vera (Aloe barbadensis) juice. Aloeride is between 4 and 7 million Da, and its glycosyl components include glucose (37.2%), galactose (23.9%), mannose (19.5%), and arabinose (10.3%). At 0.5 microg/mL Aloeride increased NF-kappa B directed luciferase expression in THP-1 human monocytic cells to levels 50% of those achieved by maximal concentrations (10 microg/mL) of LPS. Aloeride induced the expression of the mRNAs encoding IL-1beta and TNF-alpha to levels equal to those observed in cells maximally activated by LPS. Acemannan, the major carbohydrate component from aloe, used at 200 microg/mL in the macrophage assay resulted in negligible NF-kappa B activation. Analysis of acemannan and Aloeride using size-exclusion chromatography suggests that the low activity of acemannan is due to trace amounts of Aloeride. Although Aloeride comprises only 0.015% of the aloe juice dry weight, its potency for macrophage activation accounts fully for the activity of the crude juice.

PMID: 11262067 [PubMed - indexed for MEDLINE]

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References

  1. Karaca K; Sharma JM; Norgren R 1995: Nitric Oxide production by chicken macrophages activated by Acemannan. Int. J. Immuno pharmacol. 17 (3) 183-8.
  2. Imanishi K 1993: Aloctin A, an Active Substance of Aloe arborescens Miller as immuno-modulator.
  3. Pittman JC 1992: Immune enhancing effects of Aloe. Health Conscious 13 (1) 28-30.
  4. Sheets MA et al. 1991: Studies on the effect of acemannan on retrovirus infections: clinical stabilization of feline virus-infected cats. Mol. Biother. 3 41-45.
  5. Davis RH; Parker WL; Sampson RT; Murdoch DP 1991: Isolation of a stimulatory system in an Aloe extract. J Am Podiatr Med Assoc 81 (9) 473-498.
  6. Solar S et al. 1979: Mise en evidence et etude propietes immunostimulantes d’un extrait isole et partiellement purifie a partir d’Aloe vahome. Archives de l’Institut Pasteur de Madagascar 47 9-39.
  7. t’Hart LA; Van Den Berg AJ; Klus L; Van Dijk; Labadle RP 1989: An anti-complimentary polysaccharide with immunological adjuvant activity from the leaf parenchyma gel of Aloe vera. Planta Med 55 (6) 509-12.
  8. Womble D; Helderman JH 1988: Enhancement of Allo-Responsive of Human Lymphocytes by Acemannan (Carrisym). Int. J Immunopharmacol. 10 (8) 967-974.
  9. t’Hart LA; Van Den Berg AJ; Klus L; Van Dijk; Labadle RP 1989: Two functionally and chemically distinct immunomodulatory compounds in the gel of Aloe Vera. J Ethnopharmacol May-Jun 23 (1) 661-71.
  10. Yagi A 1987: Effect of Amino Acids in Aloe Extract on Phagocytosis by peripheral neutrophils in Adult Bronchial Asthma. Jpn J. Allegrol. 36 (12) 1094-1101.
  11. Shida T; Yagi A; Nishimura H; Nishioka I 1985: Effect of Aloe Extract on Peripheral Phagocytosis in Adult Bronchial Asthma. Planta Med. pp273-275.
  12. t’Hart LA; Nibbering PH; Van Den Barselaar MT; Van Dijk H; Van Den Berg AJ; Labadie RP 1990: Effects of low molecular constituents from Aloe vera gel on oxidative metabolism and cytoxic and bacterial activities of human neutrophils. Int J Immuno-pharmacol 12 (4) 427-434.
  13. Winters WD 1993: Immunoreactive Lectins in Leaf Gel from Aloe barbadensis Miller.