Structural studies of polysaccharides from aloe vera

doi:10.1016/S0008-6215(00)83936-1

Carbohydrate Research

Volume 72, July 1979, Pages 201-205

https://doi.org/10.1016/S0008-6215(00)83936-1 Get rights and content

Abstract

The mucilaginous jelly from the leaves of Aloe vera is composed of at least four different partially acetylated glucomannans that differ in their glucose-to-mannose ratios and acetyl contents. Methylation and periodate-oxidation studies indicate that the glucomannans are linear polymers containing (1→4)-glycosidic linkages.

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Cited by (75)

Structural and conformational characterization of linear O-acetyl-glucomannan purified from gel of Aloe barbadensis Miller
2018, International Journal of Biological Macromolecules
Citation Excerpt :
Different molecular weights of acemannans such as 1.2 MDa [11], >200 kDa [20] or 1.5 kDa [16] have been reported. Great discrepancies are found in the above structural features, and they have been ascribed to geographic locations [21], seasonal variations [3], cultivation conditions, [9] or preparation methods [12,20]. A polysaccharide fraction (named as AGP40) has been obtained from the gel of Aloe vera in our lab previously.
Aloe barbadensis Miller (Aloe vera) is a kind of popular medicinal and horticultural crops widely cultivated around the world. Polysaccharides with different structural features and bioactivities have been isolated from the pulp of Aloe vera. In the current study, a novel polysaccharide fraction (AGP₄₀) isolated and purified from gel juice of Aloe vera was subjected to structural and conformational analysis. AGP₄₀ had a backbone consisting of major →4)-β-Manp-(1 → residues and minor →3)-β-Manp-(1 → and →4)-β-Glcp-(1 → residues. Low degree of branches distributed at O-6 of 4-linked mannose in the main chain. The acetyl groups in AGP₄₀ presented as mono- or di-substituents (O-2, O-3, O-6, O-2,3, O-2,6 and O-3,6). AGP₄₀ performed as random coil conformation in 0.1 M NaNO₃ solution, and had fibrous filaments and irregular spherical structures in solid state. Detailed structural and conformational analysis of AGP₄₀ in the present study may greatly improve the bioactive function investigation and mechanism explanation of acetyl glucomannans in the future.
Polysaccharide isolated from Aloe vera gel suppresses ovalbumin-induced food allergy through inhibition of Th2 immunity in mice
2018, Biomedicine and Pharmacotherapy
Citation Excerpt :
It is also associated with direct activation of B cells and NK cells [31]. Aloe polysaccharides have the effect of enhancing the immune response by activation of antigen presenting cells such as dendritic cells or macrophages [32]. In addition, aloe polysaccharide is reported to maintain the intestinal immune system in a healthy state, to strengthen the intestinal mucosa, and to reduce inflammation or polyps in the intestine [11].
An allergic reaction occurs when the immune system overreacts to harmless substance called allergen that gains access to the body. Food allergy is a hypersensitive immune reaction to food proteins and the number of patients with food allergy has recently increased. Aloe Vera is used for wellness and medicinal purposes. In particular, Aloe vera has been reported to enhance immunity. However, the effect of Aloe vera on food allergy is not yet known. In this study, we investigated the effects of processed Aloe vera gel (PAG) containing low molecular weight Aloe polysaccharide (AP) on ovalbumin (OVA)-induced food allergy in mice. Allergic symptoms, rectal temperature, and diarrhea were measured in OVA-induced food allergy mice. Other allergic parameters were also analyzed by RT-PCR, ELISA, flow cytometry, and other biochemical methods. As the results, PAG suppressed the decrease of body temperature, diarrhea, and allergic symptoms in OVA-induced food allergy mice. PAG also reduced serum concentrations of type 2 helper T cell (Th2) cytokines (Interleukin-(IL)-4, IL-5, and IL-13) as well as histamine, mast cell protease-1 (MCP-1), and immunoglobulin (Ig)E. PAG blocked the degranulation of mast cells and infiltration of eosinophils in intestine. Furthermore, PAG suppressed the population of Th2 cells in spleen and mesenteric lymph nodes. PAG also increased the production of IL-10 and population of type 1 regulatory T (Tr1) cells in mice with food allergy. Taken together, our findings suggest that PAG suppressed Th2 immune responses through, at least partially, stimulating the secretion of IL-10 in food allergy mice.
Polysaccharide from leaf skin of Aloe barbadensis Miller: Part I. Extraction, fractionation, physicochemical properties and structural characterization
2017, Food Hydrocolloids
Aloe barbadensis Miller (Aloe vera) is widely used for healthy foods, medical and cosmetic products, while its leaf skin is usually treated as industrial waste. To have a profound understanding of the polysaccharides in the leaf skin of Aloe vera, crude polysaccharide was extracted from the leaf skin of Aloe vera and purified into three fractions, designated as ASP-4N, ASP-6N and ASP-8N, using gradient ammonium sulfate precipitation. The physicochemical properties and structural characteristics of ASP-4N were systematically investigated by methylation analysis and 1D/2D NMR spectroscopy. Results showed that decreasing contents of neutral sugar (79%–74%) were detected among the three fractions, with the concentration increasing of ammonium sulfate used for precipitation. Small amounts of protein and uronic acid were also detected by colorimetric method. Homogeneity identified by high performance gel permeation chromatography (HPGPC) indicated that the three fractions were highly purified. The relative weight average molecular weights for ASP-4N, ASP-6N and ASP-8N were 339, 130 and 67.6 kDa, successively. Monosaccharide compositions and characteristic FT-IR spectra of these fractions suggested the presence of typical acetylated glucomannan and the ratios of mannose/glucose were 19.13, 8.97 and 2.96, successively. Further structural analysis of ASP-4N suggested that it was a highly acetylated (1 → 4)-β-glucomannan. There was also some (1 → 3)-β-Manp mixed in the backbone.
Three phase partitioning for simultaneous purification of aloe polysaccharide and protein using a single-step extraction
2015, Process Biochemistry
In this paper, an inexpensive, rapid and efficient three phase partitioning (TPP) technique was used to simultaneously purify aloe polysaccharide (APS) and protein using a single-step extraction. This TPP system is established by adding ammonium sulfate and t-butanol to the crude slurry of aloe powder. APS was extracted in the lower phase, and the protein was extracted in the middle phase. The extraction conditions optimized were mass concentration of ammonium sulfate and t-butanol, temperature and pH. APS was further purified using a dialysis membrane to remove the salt, and its purity was determined. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was used to analyze aloe protein. TPP is an attractive and potential technique for the purification of APS and protein from Aloe vera L.
Physical properties and antibacterial activity of chitosan/acemannan mixed systems
2015, Carbohydrate Polymers
Citation Excerpt :
In turn, Table 2 shows the sugar composition of AC determined by HPAEC-PAD. The contents of mannose, glucose, and galactose determined in AC were in good agreement with previous studies (Gowda, Neelisiddaiah, & Anjaneyalu, 1979; Ni, Turner, Yates, & Tizard, 2004; Wozniewski & Gerhard, 1990). In the formation of CS polymer gel networks, the balance between hydrophilic and hydrophobic interactions is well known to be at play on the process of gel formation and in the final mechanical and thermal properties of the hydrogel materials (Goycoolea et al., 2007).
The aim of the present study was to investigate the mechanical and thermal properties of mixed chitosan–acemannan (CS–AC) mixed gels and the antibacterial activity of dilute mixed solutions of both polysaccharides. Physical hydrogels of chitosan comprising varying amounts of non-gelling acemannan were prepared by controlled neutralization of chitosan using ammonia. As the overall acemannan concentration in the mixed hydrogel increased while fixing that of CS, the mechanical strength decreased. These results indicate that AC perturbs the formation of elastic junctions and overall connectivity as it occurs in the isolated CS network. Heterotypic associations between CS and AC leading to the formation of more compact microdomains may be at play in reducing the density of the gel network consolidated by CS, possibly due to shorter gel junctions. Micro-DSC studies at pH 12.0 seem consistent with the suggestion that molecular heterotypic associations between CS and AC may be at play in determining the overall physical properties of the mixed gel systems. In dilute solution, CS showed antimicrobial activity against Staphylococcus aureus but not against Escherichia coli; AC did not exert antimicrobial activity against any of the two bacterial species. In blended solutions of both polysaccharides, as the amount of AC increased, the antimicrobial activity of the system against S. aureus ceased. In conclusion, this study demonstrates that it is feasible to incorporate acemannan in chitosan–acemannan gels and that although the mechanical strength decreases due to the presence of AC, the gel network persists even at high amount of AC. This study anticipates that the CS–AC mixed gels may offer promise for the future development of biomaterials such as scaffolds to be used in wound therapy.
Qualitative improvement of low meat beef burger using Aloe vera
2014, Meat Science
Citation Excerpt :
This could be attributed to the high water holding capacity and moisture retention of Aloe vera during cooking. Aloe vera has a mucilaginous jelly texture that is composed of at least four different glucomannans which are partially acetylated and have different acetyl contents and glucose-to-mannose ratios (Channe Gowda, Neelisiddaiah, & Anjaneyalu, 1979). These mucilaginous compounds sequester high amounts of water in their structure and retain moisture during cooking.
Low meat beef burgers have found their niche in the food markets in developing countries because of their lower price. However, these burgers still lack an acceptable quality. This study investigates the effects of different concentrations of Aloe vera on the quality of this food product. For this purpose, beef burgers were produced with 0%, 1%, 3%, and 5% Aloe vera and the changes in their cooking parameters, lipid oxidation, texture, and appeal to consumers over 7 days of refrigerated storage were evaluated. Results indicate that Aloe vera contributed to some extent to decreased cooking loss and diameter reduction in the burgers. Increased concentrations of Aloe vera led to improvements in the water absorption and texture of the burgers as well as their lipid stability. However, a concentration level of 3% led to the most acceptability of the product to the panelists. Finally, it was found that Aloe vera acts as a hydrocolloid and improves the quality of burgers.

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Structural studies of polysaccharides from aloe vera

Abstract

Carbohydr. Res.

Adv. Carbohydr. Chem. Biochem.

Methods Carbohydr. Chem.

J. Am. Chem. Soc.

J. Biochem. (Tokyo)