Decreased mortality of Norman murine sarcoma in mice treated with the immunomodulator, Acemannan

An extract from the parenchyma of Aloe barbadensis Miller shown to contain long chain polydispersed beta (1,4)-linked mannan polymers with random O-acetyl groups (acemannan, Carrisyn) was found to initiate the phagocyte production of monokines that supported antibody dependent cellular cytotoxicity and stimulated blastogenesis in thymocytes. Acemannan, in both enriched and highly purified forms, was administered intraperitoneally to female CFW mice into which murine sarcoma cells had been subcutaneously implanted. The rapidly growing, highly malignant and invasive sarcoma grew in 100% of implanted control animals, resulting in mortality in 20 to 46 days, dependent on the number of cells implanted. Approximately 40% of animals treated with acemannan at the time of tumor cell implantation (1.5 x 10(6) cells) survived. Tumors in acemannan-treated animals exhibited vascular congestion, edema, polymorphonuclear leukocyte infiltration, and central necrosing foci with hemorrhage and peripheral fibrosis. The data indicate that in vivo treatment of peritoneal macrophages stimulates the macrophage production of monokines, including interleukin-1 and tumor necrosis factor. The data further indicate that sarcomas in animals treated i.p. with acemannan at the time of tumor cell implantation were infiltrated by immune system cells, became necrotic, and regressed. The combined data suggest that acemannan-stimulated synthesis of monokines resulted in the initiation of immune attack, necrosis, and regression of implanted sarcomas in mice.

The isolation of an active inhibitory system from an extract of aloe vera

An Aloe vera extract was prepared with 50% ethanol. The resultant supernatant and precipitate were tested for anti-inflammatory activity using the croton oil-induced ear-swelling assay. The supernatant fraction decreased inflammation, when applied topically, by 29.2%, and the precipitate decreased inflammation by 12.1%. The authors have shown that the anti-inflammatory activity (inhibitory system) resides in the supernatant of a 50% ethanol extract.

Studies of aloe. III. Mechanism of cathartic effect. (2)

The mechanism of action of aloe-emodin-9-anthrone, a decomposition product of barbaloin, in causing a significant increase in the water content of the rat large intestine, was investigated. Aloe-emodin-9-anthrone inhibited rat colonic Na+, K(+)-adenosine triphosphatase (ATPase) in vitro, and increased the paracellular permeability across the rat colonic mucosa in vivo. Therefore, it seemed that the increase in water content of the rat large intestine produced by aloe-emodin-9-anthrone was due to both inhibition of absorption and stimulation of secretion without stimulation of peristalsis. Furthermore, pretreatment with loperamide, an antidiarrheal agent, completely prevented the increase of paracellular permeability induced by aloe-emodin-9-anthrone but did not completely reduce the concomitant increase in residual fluid volume. These findings suggest that aloe-emodin-9-anthrone has multiple mechanisms of action involved in the increase of water content in the rat large intestine.

An anti-complementary polysaccharide with immunological adjuvant activity from the leaf parenchyma gel of Aloe vera

The aim of the study is to develop new substances with immunomodulatory activity. To this end, extracts from plants used in traditional medicine are used as starting material. This study deals with the mucilagenous leaf-gel of Aloe vera which is well reputed for its therapeutical effect on inflammatory-based disorders. The purification of an aqueous gel-extract guided by inhibition of complement activity in HPS is described. Using anion-exchange and gel permeation chromatography a highly active polysaccharide fraction was isolated, that is present in the gel in various chain lengths. The polysaccharides consist of several monosaccharides of which mannose is dominant. The inhibition is based on alternative pathway activation, resulting in consumption of C3. With respect to their biological activity the polysaccharides inhibit the opsonization of zymosan in HPS and display adjuvant activity on specific antibody production and the induction of delayed type hypersensitivity in mice.

Effect of water extracts of aloe and some herbs in decreasing blood ethanol concentration in rats. II

Oral administration of ethanol to rats at a dose of 3 g/kg decreased alcohol dehydrogenase (ADH) activity and metabolism of lactate to pyruvate in the liver. The effects of water extracts of Aloe and some other herbs on blood ethanol concentration and on ADH activity in liver cytosol were examined. The water extracts of these herbs caused a faster elimination of ethanol from blood of normal rats when administered orally 30 min before oral administration of ethanol. The rapid elimination of ethanol seems to be due to a protection of ADH activity and the supply of nicotinamide dinucleotide, both of which are reduced by high ethanol concentration. The effects of ethanol in decreasing the enzyme activities relating to its own metabolism occur when high concentrations of ethanol pass through the liver, and thus may primarily appear during the absorption of alcohol from the gastrointestinal tract, when portal concentration of ethanol are very high.

Aloe vera

We review the scientific literature regarding the aloe vera plant and its products. Aloe vera is known to contain several pharmacologically active ingredients, including a carboxypeptidase that inactivates bradykinin in vitro, salicylates, and a substance(s) that inhibits thromboxane formation in vivo. Scientific studies exist that support an antibacterial and antifungal effect for substance(s) in aloe vera. Studies and case reports provide support for the use of aloe vera in the treatment of radiation ulcers and stasis ulcers in man and burn and frostbite injuries in animals. The evidence for a potential beneficial effect associated with the use of aloe vera is sufficient to warrant the design and implementation of well-controlled clinical trials.

The influence of selected potential oncostatics of plant origin on the protein biosynthesis in vitro

Five potential oncostatics of plant origin (reserpine, amphotericin B, rutoside, digoxin, dry aloe extract), and cyclic AMP were investigated for their effect on protein synthesis. The solutions of digoxin and dry aloe extract inhibited protein biosynthesis in vitro. The direct inhibiting effect of digoxin on the ribosomes suggests that this drug forms an inactive complex with this organelle. Therefore it can be concluded that ribosome is the target site of digoxin action. Aloin and aloeemodin are responsible for the inhibitory effect of the solution of dry aloe extract. They inhibit markedly [14C]-leucine incorporation into proteins. Aloin and aloeemodin do not influence directly the ribosomes, but they inhibit elongation factors and peptidyltransferase activities in the complete elongation system. Some preliminary experiments have shown that direct interaction between these substances and elongation factor EF-2 should be taken in account. This observation is the subject of further experiments, in which the characteristics of the inhibitory effect of the components isolated from dry aloe extract will be performed.

Studies on the activity of individual plants of an antidiabetic plant mixture

A blood glucose lowering extract of a mixture of five plants in use by Kuwaiti diabetics was studied for the identification of its active component(s). Only the extracts of myrrh and aloe gums effectively increased glucose tolerance in both normal and diabetic rats. The remaining components, gum olibanum, Nigella sativa seeds and gum assafoetida were without effect.

The glucomannan system from Aloe vahombe (liliaceae). III. Comparative studies on the glucomannan components isolated from the leaves

The polysaccharide mixture obtained by hot water extraction of Aloe vahombe leaves is composed of at least four different paritally acetylated glucomannans which differ in molecular weight, glucose to mannose ratios and acetyl contents. Furthermore, one fraction contains a small but significant amount of protein which could not be removed by gel filtration in a hydrogen-bond-breaking medium, by DEAE-Sephadex A-50 anion exchange chromatography, or by Sevag's method.

The Aloe vera phenomenon: a review of the properties and modern uses of the leaf parenchyma gel

The mucilaginous gel from the parenchymatous cells in the leaf pulp of Aloe vera has been used since early times for a host of curative purposes. This gel should be distinguished clearly from the bitter yellow exudate originating from the bundle sheath cells, which is used for its purgative effects. Aloe vera gel has come to play a prominent role as a contemporary folk remedy, and numerous optimistic, and in some cases extravagant, claims have been made for its medicinal properties. Modern clinical use of the gel began in the 1930s, with reports of successful treatment of X-ray and radium burns, which led to further experimental studies using laboratory animals in the following decades. The reports of these experiments and the numerous favourable case histories did not give conclusive evidence, since although positive results were usually described, much of the work suffered from poor experimental design and insufficiently large test samples. In addition some conflicting or inconsistent results were obtained. With the recent resurgence of interest in Aloe vera gel, however, new experimental work has indicated the possibility of distinct physiological effects. Chemical analysis has shown the gel to contain various carbohydrate polymers, notably either glucomannans or pectic acid, along with a range of other organic and inorganic components. Although many physiological properties of the gel have been described, there is no certain correlation between these and the identified gel components.

Isolation of a new aloe-emodin dianthrone diglucoside from senna and its potentiating effect on the purgative activity of sennoside A in mice

Two aloe-emodin dianthrone diglucosides (I and II) were isolated from the leaves of Cassia angustifolia Vahl by successive column chromatography with Amberlite XAD-2, silica gel, Polyamide C-200 and Sephadex LH-20. The stereostructures of I and II were elucidated as trans and meso isomers at 10-10', respectively, from the patterns of the ultraviolet absorption spectra and circular dichroism curves. This is the first report of isolation of diglucoside I from senna. Despite the lack of purgative activity, diglucoside I exerts a potentiating effect of about 1.3 times on the purgative activity of sennoside A in mice when even 15% is included in the mixture. The difference between I and a third active glycoside based on aloe-emodin is also discussed.

Effect of aloe lectin on deoxyribonucleic acid synthesis in baby hamster kidney cells

A homogeneous glycoprotein (mol. wt 40,000) containing 34% carbohydrate was isolated from Aloe arborescens var. natalensis. At a concentration of 5 micrograms/ml, this glycoprotein was shown to stimulate deoxyribonucleic acid (DNA) synthesis in baby hamster kidney (BHK) cells and to have the properties of a lectin which reacts with sheep blood cells. The chemical and physical properties of the glycoprotein (aloe lectin) are also discussed.

Liquid chromatographic determination of barbaloin (aloin) in foods

A simple and rapid liquid chromatographic method is described for the determination of barbaloin (aloin, 10-D-glucopyranosyl-1,8-dihydroxy-3-(hydroxymethyl)-9(10H)-anthraceno ne) in foods. Barbaloin is extracted with water from foods containing aloe and the extract is cleaned up on a disposable cartridge by using methanol-water (55 + 45) as eluant. The eluted barbaloin is separated by liquid chromatography on a YMC A-302 column with methanol-water (50 + 50) mobile phase, and detected at 293 nm. Recoveries of barbaloin added to foods at the levels of 0.05 and 0.50 mg/g were 94.4-100%. Assay results for commercial food samples indicated that the present method is applicable to a variety of foods supplemented with aloe.

Structure determination of polysaccharides in Aloe saponaria (Hill.) Haw. (Liliaceae)

Neutral polysaccharides that inhibit carrageenin-induced edema in rats were isolated from the nondialysate of the pulp of Aloe saponaria by gel filtration. These were shown to be a linear polymer of a 1,4-linked beta-D-mannopyranose (mol. wt. 15,000) containing 18% acetyl groups (As mannan 1), and a 1,4-linked alpha-D-mannopyranose polymer containing a single branch on the principal chain consisting of D-glucose residues linked at C-2 and C-4 (mol. wt. 66,000), with 10% acetyl groups (As mannan 2). As mannan 1 inhibited carrageenin-induced hind paw edema at 50 mg/kg ip in rats; As mannan 2 was not tested for pharmacological activity. A crude preparation of both As mannans was effective when given intraperitoneally, but was ineffective when given orally.

Antibradykinin active material in Aloe saponaria

A material having antibradykinin activity on isolated guinea pig ileum was partially purified from the nondialysate of the pulp of Aloe saponaria by repetition of gel chromatography using a hydrophilic polyvinyl gel and dextran gels. From the results of amino acid and carbohydrate analyses, the antibradykinin-active material was estimated to be a glycoprotein. It was found that this material catalyzes the hydrolysis of bradykinin at pH 7.4. The results of peptide analysis using reversed-phase high-performance liquid chromatography coupled with amino acid analysis indicate that this glycoprotein cleaves the Gly4-Phe5 and Pro7-Phe8 bonds of the bradykinin molecule.

Purification and characterization of two lectins from Aloe arborescens Mill

Two lectins have been isolated from leaves of Aloe arborescens Mill by salt precipitation, pH-dependent fractionation and gel filtration. One lectin (P-2) has a molecular weight of approximately 18,000, consists of two subunits (alphabeta) and contains more than 18% by weight of neutral carbohydrate. The smaller subunit (alpha) has a molecular weight of approximately 7,500 and the larger subunit (beta) a molecular weight of approximately 10,500. The other lectin (S-1) has a molecular weight of approximately 24,000, consists of two subunits (gamma2) with a molecular weight of approximately 12,000 and contains more than 50% by weight of neutral carbohydrate. An interesting feature of the amino acid compositions of these lectins is the high proportion of acidic amino acids, such as aspartic acid and glutamic acid, and the low proportion of methionine and histidine. S-1 has a strong hemagglutinating activity. On the other hand, P-2 has not only hemagglutinating activity but also mitogenic activity on lymphocytes, precipitate-forming reactivity with serum proteins, one of which is alpha2-macroglobulin, and complement C3 activating activity via the alternate pathway.

Biologically active constituents of leaves and roots of Aloe arborescens var. natalensis

Several biologically active substances, such as aloenin (1), magnesium lactate, aloe-emodin (4), barbaloin (5), and succinic acid, were found to be contained in the leaf juice of Aloe arborescens Mill. var. natalensis Berger, which has widely been used in domestic medicines. Aloenin (1) and magnesium lactate were elucidated to exhibit an inhibitory action on the gastric juice secretion of rats. Various constituents other than the above bioactive substances were found in the leaves and the roots of the plant.