Antiinflammatory C-glucosyl chromone from Aloe barbadensis

One-step separation and purification of two chromones and one pyrone from Aloe barbadensis Miller: a comparison between reversed-phase flash chromatography and high-speed counter current chromatography

INTRODUCTION

Chromones and pyrones are the major secondary metabolites of Aloe barbadensis Miller. As they are minor components of the plant, an efficient purification procedure for them is of great importance for promoting their pharmacological studies.

OBJECTIVE

To develop efficient methods for one-step separation and purification of two chromones (5-((S)-2'-oxo-4'-hydroxypentyl)-2-hydroxymethylchromone (1) and 5-((4E)-2'-oxo-pentenyl)-2-hydroxymethylchromone (3)) and one pyrone (aloenin aglycone (2)) from A. barbadensis via reversed-phase flash chromatography (RP-FC) and high-speed counter current chromatography (HSCCC).

METHODS

The RP-FC separation was performed using methanol:water (26:74, v/v) as the mobile phase at a flow rate of 20 mL/min. A solvent system composed of dichloromethane:methanol:water (3:1.5:1, v/v/v) was used for the HSCCC separation, at a flow rate of 2.0 mL/min.

RESULTS

A one-step RP-FC operation within 110 min was successfully used for the purification of compounds 1 (27.9 mg, 96.5%), 2 (32.4 mg, 98.2%) and 3 (4.1 mg, 99.0%) from 129 mg of crude sample, and a one-step HSCCC separation within 95 min was successfully implemented for the purification of compounds 1 (31.1 mg, 97.6%), 2 (35.8 mg, 96.7%) and 3 (2.7 mg, 98.1%) from 134 mg of crude sample.

CONCLUSION

The developed procedures were efficient, with low cost and high yield, which would afford sufficient amounts of high-purity compounds for chromatographic purposes and pharmacological activity screening.

Blood glucose lowering activity of aloe based composition, UP780, in alloxan induced insulin dependent mouse diabetes model

BACKGROUND

There are a few nutritional approaches to address the increased needs of managing diabetic conditions. Previously it has been reported that UP780, a standardized composition of aloe chromone formulated with an aloe polysaccharide, has a significant impact in reducing HbA1C, fasting blood glucose, fructosamine and plasma insulin level in humans and improved impaired glucose and insulin resistance in high-fat diet-induced and db/db non-insulin dependent diabetic mouse models. Here we describe activity of UP780 and its constituents to improve insulin sensitivity in alloxan induced insulin dependent diabetic mouse model.

MATERIALS AND METHOD

Insulin dependent diabetes was induced by administering a single intraperitoneal injection of alloxan monohydrate at a dose of 150 mg/kg to CD-1 mice. Aloesin (UP394) was formulated with an Aloe vera inner leaf gel powder polysaccharide (Qmatrix) to yield a composition designated UP780. Efficacy of oral administration of UP780 at 2000 mg/kg and its constituents (aloesin at 80 mg/kg and Qmatrix at 1920 mg/kg) were evaluated in this model. Glyburide, a sulfonylurea drug used in the treatment of type 2 diabetes, was used at 5 mg/kg as a positive control. Effect of UP780 on non-diabetic normal mice was also addressed.

RESULTS

Mice administered intraperitoneal alloxan monohydrate developed progressive type-1 diabetes like symptom. After 4 weeks of daily oral administration, reductions of 35.9%, 17.2% and 11.6% in fasting blood glucose levels were observed for UP780, the UP780 Aloe vera inner leaf gel polysaccharide preparation without chromone (Qmatrix), and Aloesin (UP394), treated animals respectively, compared to vehicle treated animals. UP780 has no impact on blood glucose level of non-diabetic healthy mice. UP780 showed statistically significant improvement for blood glucose clearance in oral glucose tolerance tests. Similarly, enhanced improvement in plasma insulin level and statistically significant reduction in triglyceride level was also observed for animals treated with the composition.

CONCLUSION

These findings suggest that UP780, a chromone standardized Aloe based composition, could possibly be used as a natural supplement alternative to facilitate maintenance of healthy blood glucose levels.

Anticonvulsant activity of Aloe vera leaf extract in acute and chronic models of epilepsy in mice

Objectives

The effect of Aloe vera in epilepsy has not yet been explored. This study was done to explore the effect of aqueous extract of Aloe vera leaf powder on three acute and one chronic model of epilepsy.

Methods

In acute study, aqueous extract of Aloe vera leaf (extract) powder was administered in doses 100, 200 and 400 mg/kg p.o. Dose of 400 mg/kg of Aloe vera leaf extract was chosen for chronic administration. Oxidative stress parameters viz. malondialdehyde (MDA) and reduced glutathione (GSH) were also estimated in brain of kindled animals.

Key findings

In acute study, Aloe vera leaf (extract) powder in a dose-dependent manner significantly decreased duration of tonic hind limb extension in maximal electroshock seizure model, increased seizure threshold current in increasing current electroshock seizure model, and increased latency to onset and decreased duration of clonic convulsion in pentylenetetrazole (PTZ) model as compared with control group. In chronic study, Aloe vera leaf (extract) powder prevented progression of kindling in PTZ-kindled mice. Aloe vera leaf (extract) powder 400 mg/kg p.o. also reduced brain levels of MDA and increased GSH levels as compared to the PTZ-kindled non-treated group.

Conclusions

The results of study showed that Aloe vera leaf (extract) powder possessed significant anticonvulsant and anti-oxidant activity.

Clinical efficacy of new aloe vera- and myrrh-based oral mucoadhesive gels in the management of minor recurrent aphthous stomatitis: a randomized, double-blind, vehicle-controlled study

OBJECTIVE

To evaluate the clinical efficacy, and safety of newly customized natural oral mucoadhesive gels, containing either aloe vera or myrrh as active ingredients, in the management of minor recurrent aphthous stomatitis (MiRAS).

SUBJECTS AND METHODS

Ninety subjects with MiRAS were recruited from Oral Medicine Clinic, at Faculty of Dentistry, King Abdulaziz University, Saudi Arabia, for this randomized, double-blind, placebo-controlled study. Two new natural gels, containing aloe vera and myrrh, were prepared in a concentration of (0.5% w/w), in addition to a plain mucoadhesive gel used as a placebo. Patients with fresh ulcers (<48-h duration) were instructed to apply either one of the three gels four times a day for a period of 5 days. Clinical efficacy was investigated in the form of changes in ulcer size, pain intensity, erythema, and exudation at days 4 and 6 of study entry. Participants were interviewed for the emergence of any side effects.

RESULTS

76.6% of patients using aloe gel showed complete ulcer healing, 86.7%, and 80% of them revealed subsidence of erythema and exudation, respectively, especially at day 6 visit, whereas 76.7% of myrrh-treated patients revealed almost absence of pain at day 6. No side effects were encountered with the use of any of the three gels.

CONCLUSION

The new formulated aloe- and myrrh-based gels proved to be effective in topical management of MiRAS. Aloe was superior in decreasing ulcer size, erythema, and exudation; whereas myrrh resulted in more pain reduction.

Dietary Aloe vera components' effects on cholesterol lowering and estrogenic responses in juvenile goldfish, Carassius auratus

Aloes are now considered a very interesting source of bioactive compounds among which phytosterols should play a major role. The present study is an attempt to investigate the hypocholesterolemic activity of Aloe vera associated with its impact on the reproductive status of juvenile goldfish. Therefore, the short- and long-term effects of feeding supplementary diet containing aloe components (20 mg aloe/g diet; 2%) on plasma lipids, plasma vitellogenin, and hepatic estrogen receptor α/β1 mRNA levels in goldfish were examined. Results of GC-MS for phytosterols show high abundance of β-sitosterol in freeze-dried powder of Aloe vera whole leaves. Moreover, a 2% aloe powder dietary supplement was not found estrogenic in juvenile goldfish after either 7- or 30-day treatment, but was consistent in plasma hypocholesterolemic effects following long-term exposure. The present data further support that plasma cholesterol modulation induced by phytosterols may not be related to estrogen-like activity.

Pharmacological attribute of Aloe vera: Revalidation through experimental and clinical studies

Aloe vera has long been used as a traditional medicine for inducing wound healing. It is a natural product that now a days is used in cosmetic industry. Benefits associated with Aloe vera have been attributed to the polysaccharides contained in the gel of the leaves though there are various indications for its use. Biological activities include promotion of wound healing, antifungal activity, anti-inflammatory, anticancer and immunomodulatory. Gingival fibroblasts play an important role in oral wound healing. Double blind-controlled trials are needed to determine its real efficacy in oral health.

Processing, food applications and safety of aloe vera products: a review

Aloe vera is used for vigor, wellness and medicinal purposes since rigvedic times. Health benefits of aloe vera include its application in wound healing, treating burns, minimizing frost bite damage, protection against skin damage from x-rays, lung cancer, intestinal problems, increasing high density lipoprotein (HDL), reducing low density lipoprotein (LDL), reducing blood sugar in diabetics, fighting acquired immune deficiency syndrome (AIDS), allergies and improving immune system. Phytochemistry of aloe vera gel has revealed the presence of more than 200 bioactive chemicals. Aloe vera gel is extracted from its leaves and appropriate processing techniques are needed for stabilization as well as preparation of the end products. The industries involved in processing of aloe vera need Government surveillance to ensure that the aloe vera products have beneficial bio-active chemicals as per claims of the manufacturers. Regulatory bodies also need to look into the safety and toxicological aspects of aloe vera products for food applications. The claims made for medicinal value of aloe products should be supported by authentic and approved clinical trial data. It is presumptive to mention that nutraceutical claims of aloe products made by the manufacturers are numerous. However, approved clinical evidences are available only for lowering LDL, increasing HDL, decreasing blood glucose level, treating genital herpes and psoriases.

Aloe vera as a functional ingredient in foods

The main scientific discoveries on Aloe vera published mainly in the last three decades are presented in this work. After describing Aloe from a botanical point of view, the papers related with the chemical composition of different parts of the leaf of Aloe, particularly those in which the gel is described and are presented in a synthetic manner. The chemical analyses reveal that Aloe gel contains mannose polymers with some glucose and other sugars, among which the most important is Acemannan. Besides these, other components such as glycoproteins, enzymes, amino acids, vitamins, and minerals are described. Different factors also affecting the chemical composition of the gel, such as species and variety, climatic and soil conditions, cultivation methods, processing and preservation, are enumerated and discussed. On the other hand, the main therapeutic applications have been revised and the possible damaging effects of Aloe are also commented upon. A special emphasis is placed on the biologically active compounds or groups of compounds responsible for the therapeutic applications and which are their action mechanisms. The paper concludes that more research is needed to confirm the therapeutic and beneficial effects and to definitively clarify the myth surrounding Aloe vera. A general view on the problem of the commercialization and establishment of the quality and safety of Aloe products in the food industry has been offered here. The main points and European regulations that need to be considered regarding the quality control of prepared Aloe products are presented in this paper.

A HPTLC densitometric method for the determination of aloeverose in Aloe vera gel

Aloe vera gel is a familiar ingredient in a range of widely available and advertisement healthcare and cosmetic products. As to date there are no documented reports on the standardization of A. vera gel and the following study is an attempt in this direction. A. vera gel was evaluated for its aloeverose content for the first time. Aloeverose, was separated on a thin-layer of silica gel by isocratic gradient elution technique was determined by using HPTLC-photodensitometry. The proposed method is simple and sensitive and can be used for the routine assay of aloeverose in phytomedicines containing A. vera gel.

Final report on the safety assessment of AloeAndongensis Extract, Aloe Andongensis Leaf Juice,aloe Arborescens Leaf Extract, Aloe Arborescens Leaf Juice, Aloe Arborescens Leaf Protoplasts, Aloe Barbadensis Flower Extract, Aloe Barbadensis Leaf, Aloe Barbadensis Leaf Extract, Aloe Barbadensis Leaf Juice,aloe Barbadensis Leaf Polysaccharides, Aloe Barbadensis Leaf Water, Aloe Ferox Leaf Extract, Aloe Ferox Leaf Juice, and Aloe Ferox Leaf Juice Extract

Plant materials derived from the Aloe plant are used as cosmetic ingredients, including Aloe Andongensis Extract, Aloe Andongensis Leaf Juice, Aloe Arborescens Leaf Extract, Aloe Arborescens Leaf Juice, Aloe Arborescens Leaf Protoplasts, Aloe Barbadensis Flower Extract, Aloe Barbadensis Leaf, Aloe Barbadensis Leaf Extract, Aloe Barbadensis Leaf Juice, Aloe Barbadensis Leaf Polysaccharides, Aloe Barbadensis Leaf Water, Aloe Ferox Leaf Extract, Aloe Ferox Leaf Juice, and Aloe Ferox Leaf Juice Extract. These ingredients function primarily as skin-conditioning agents and are included in cosmetics only at low concentrations. The Aloe leaf consists of the pericyclic cells, found just below the plant's skin, and the inner central area of the leaf, i.e., the gel, which is used for cosmetic products. The pericyclic cells produce a bitter, yellow latex containing a number of anthraquinones, phototoxic compounds that are also gastrointestinal irritants responsible for cathartic effects. The gel contains polysaccharides, which can be acetylated, partially acetylated, or not acetylated. An industry established limit for anthraquinones in aloe-derived material for nonmedicinal use is 50 ppm or lower. Aloe-derived ingredients are used in a wide variety of cosmetic product types at concentrations of raw material that are 0.1% or less, although can be as high as 20%. The concentration of Aloe in the raw material also may vary from 100% to a low of 0.0005%. Oral administration of various anthraquinone components results in a rise in their blood concentrations, wide systemic distribution, accumulation in the liver and kidneys, and excretion in urine and feces; polysaccharide components are distributed systemically and metabolized into smaller molecules. aloe-derived material has fungicidal, antimicrobial, and antiviral activities, and has been effective in wound healing and infection treatment in animals. Aloe barbadensis (also known as Aloe vera)-derived ingredients were not toxic in acute oral studies using mice and rats. In parenteral studies, the LD(50) using mice was > 200 mg/kg, rats was > 50 mg/kg, and using dogs was > 50 mg/kg. In intravenous studies the LD(50) using mice was > 80 mg/kg, rats was > 15 mg/kg, and dogs was > 10 mg/kg. The 14-day no observed effect level (NOEL) for the Aloe polysaccharide, acemannan, in the diet of Sprague-Dawley rats, was 50,000 ppm or 4.1 to 4.6 g/kg day(-1). In a 3-month study using mice, Aloe vera (extracted in ethanol) given orally in drinking water at 100 mg/kg produced reproductive toxicity, inflammation, and mortality above that seen in control animals. Aloe vera extracted in methanol and given to mice at 100 mg/kg in drinking water for 3 months caused significant sperm damage compared to controls. Aloe barbadensis extracted with water and given to pregnant Charles Foster albino rats on gestational days (GDs) 0 through 9 was an abortifacient and produced skeletal abnormalities. Both negative and positive results were found in bacterial and mammalian cell genotoxicity assays using Aloe barbadensis-derived material, Aloe Ferox-derived material, and various anthraquinones derived from Aloe. Aloin (an anthraquinone) did not produce tumors when included in the feed of mice for 20 weeks, nor did aloin increase the incidence of colorectal tumors induced with 1,2-dimethylhydrazine. Aloe-emodin (an anthraquinone) given to mice in which tumor cells had been injected inhibited growth of malignant tumors. Other animal data also suggest that components of Aloe inhibit tumor growth and improve survival. Various in vitro assays also demonstrated anticarcinogenic activity of aloe-emodin. Diarrhea was the only adverse effect of note with the use of Aloe-derived ingredients to treat asthma, ischemic heart disease, diabetes, ulcers, skin disease, and cancer. Case reports include acute eczema, contact urticaria, and dermatitis in individuals who applied Aloe-derived ingredients topically. The Cosmetic Ingredient Review Expert Panel concluded that anthraquinone levels in the several Aloe Barbadensis extracts are well understood and can conform to the industry-established level of 50 ppm. Although the phototoxicity anthraquinone components of Aloe plants have been demonstrated, several clinical studies of preparations derived from Aloe barbadensis plants demonstrated no phototoxicity, confirming that the concentrations of anthraquinones in such preparations are too low to induce phototoxicity. The characterization of aloe-derived ingredients from other species is not clear. In the absence of well-characterized derivatives, biological studies of these materials are considered necessary. The studies needed are 28-day dermal toxicity studies on Aloe Andongensis Extract, Aloe Andongensis Leaf Juice, Aloe Arborescens Leaf Extract, Aloe Arborescens Leaf Juice, Aloe Ferox Leaf Extract, Aloe Ferox Leaf Juice, and Aloe Ferox Leaf Juice (ingredients should be tested at current use concentrations). In Aloe-derived ingredients used in cosmetics, regardless of species, anthraquinone levels should not exceed 50 ppm. The Cosmetic Ingredient Review Expert Panel advised the industry that the total polychlorobiphenyl (PCB)/pesticide contamination of any plant-derived cosmetic ingredient should be limited to not more than 40 ppm, with not more than 10 ppm for any specific residue and that limits were appropriate for the following impurities: arsenic (3 mg/kg maximum), heavy metals (20 mg/kg maximum), and lead (5 mg/kg maximum).

Aloe vera: a short review

Aloe vera is a natural product that is now a day frequently used in the field of cosmetology. Though there are various indications for its use, controlled trials are needed to determine its real efficacy. The aloe vera plant, its properties, mechanism of action and clinical uses are briefly reviewed in this article.

Aloin induces apoptosis in Jurkat cells

Aloe is widely used as a dietary supplement. However, there are continuing concerns over the toxicity and the purity of aloe-based products. The primary class of compounds responsible for aloe-induced toxicity are anthraquinones. One of these, aloe-emodin, has been extensively investigated for apoptosis inducing effects. Conversely, the precursor to aloe-emodin, aloin, has been subjected to only minimal investigation of any cytotoxic effects. Jurkat T cells, an established model for the study of compound toxicity, were used to evaluate the effect of aloin on cell viability. Cells were analyzed using flow cytometry and microscopy for cell size and granularity, cell membrane integrity, mitochondrial membrane potential, and cell cycle profile. Treatment with aloin resulted in a reduction in cell size, compromised membrane integrity, and loss of mitochondrial membrane potential in a dose-dependent manner. Additionally, treatment with aloin resulted in alteration of the cell cycle, specifically a block at G2/M phase. Importantly, the loss of cell membrane integrity was preceded by a loss of mitochondrial membrane potential, suggesting a mitochondrial-dependent pathway for aloin-induced apoptosis. These observations provide insight into the potential mechanisms of aloin-induced toxicity and thus, perhaps, aloe preparation-induced toxicity. Furthermore, because of the concern over the safety of aloe-based supplements, this work suggests that aloe supplements not containing aloin may be safer than aloe supplements containing aloin, and that aloin should be considered in addition to concentrations of aloe-emodin.

In vitro 5-lipoxygenase and anti-oxidant activities of South African medicinal plants commonly used topically for skin diseases

An investigation was undertaken to determine the possible mechanisms of action of medicinal plants used for dermatological pathologies. A total of 14 plant species were selected from the readily available ethnobotanical literature. 5-Lipoxygenase and DPPH (2,2-diphenyl-1-picrylhydrazyl) assays were used to determine the anti-inflammatory activity and the anti-oxidant activity of selected medicinal plants, respectively. Both aqueous and methanol extracts were tested. Among the plants screened, four species (Croton sylvaticus, Warburgia salutaris, Pentanisia prunelloides, and Melianthus comosus) displayed promising 5-lipoxygenase inhibitory activity with IC(50) values <61 ppm. A large number of plants exhibited significant anti-oxidant activities with IC(50) values between 5.27 and 83.36 ppm. Aqueous extracts of M. comosus exhibited the most potent anti-inflammatory and anti-oxidant activity.

An evaluation of the biological and toxicological properties of Aloe barbadensis (miller), Aloe vera

Aloe barbadensis (Miller), Aloe vera, has a long history of use as a topical and oral therapeutic. The plant is the source of two products, gel and latex, which are obtained from its fleshy leaves. Aloe vera products contain multiple constituents with potential biological and toxicological activities, yet the active components elude definition. Ingestion of Aloe vera is associated with diarrhea, electrolyte imbalance, kidney dysfunction, and conventional drug interactions; episodes of contact dermatitis, erythema, and phototoxicity have been reported from topical applications. This review examines the botany, physical and chemical properties, and biological activities of the Aloe vera plant.

FTIR and FTR spectral studies of 2-amino-6-bromo-3-formylchromone

FTIR and FT-Raman spectra of 2-amino-6-bromo-3-formylchromone (ABFC) have been recorded, using Bruker IFS 66V spectrometer. A detailed vibrational spectral analysis carried out and assignments of the observed bands have been proposed on the basis of fundamentals, overtones and combinations, by assuming C(S) point group symmetry. A normal coordinate analysis has been performed to characterise the vibrational fundamentals in terms of potential energy distribution (PED).

Randomized, double-blind, placebo-controlled trial of oral aloe vera gel for active ulcerative colitis

BACKGROUND

The herbal preparation, aloe vera, has been claimed to have anti-inflammatory effects and, despite a lack of evidence of its therapeutic efficacy, is widely used by patients with inflammatory bowel disease.

AIM

To perform a double-blind, randomized, placebo-controlled trial of the efficacy and safety of aloe vera gel for the treatment of mildly to moderately active ulcerative colitis.

METHODS

Forty-four evaluable hospital out-patients were randomly given oral aloe vera gel or placebo, 100 mL twice daily for 4 weeks, in a 2 : 1 ratio. The primary outcome measures were clinical remission (Simple Clinical Colitis Activity Index </= 2), sigmoidoscopic remission (Baron score </= 1) and histological remission (Saverymuttu score </= 1). Secondary outcome measures included changes in the Simple Clinical Colitis Activity Index (improvement was defined as a decrease of >/= 3 points; response was defined as remission or improvement), Baron score, histology score, haemoglobin, platelet count, erythrocyte sedimentation rate, C-reactive protein and albumin.

RESULTS

Clinical remission, improvement and response occurred in nine (30%), 11 (37%) and 14 (47%), respectively, of 30 patients given aloe vera, compared with one (7%) [P = 0.09; odds ratio, 5.6 (0.6-49)], one (7%) [P = 0.06; odds ratio, 7.5 (0.9-66)] and two (14%) [P < 0.05; odds ratio, 5.3 (1.0-27)], respectively, of 14 patients taking placebo. The Simple Clinical Colitis Activity Index and histological scores decreased significantly during treatment with aloe vera (P = 0.01 and P = 0.03, respectively), but not with placebo. Sigmoidoscopic scores and laboratory variables showed no significant differences between aloe vera and placebo. Adverse events were minor and similar in both groups of patients.

CONCLUSION

Oral aloe vera taken for 4 weeks produced a clinical response more often than placebo; it also reduced the histological disease activity and appeared to be safe. Further evaluation of the therapeutic potential of aloe vera gel in inflammatory bowel disease is needed.

[Anti-inflammatory constituents, aloesin and aloemannan in Aloe species and effects of tanshinon VI in Salvia miltiorrhiza on heart]

Cinnamoyl, p-coumaroyl, feruloyl, caffeoyl aloesin, and related compounds were isolated from Aloe species. The antiinflammatory and antioxidative activities of these compounds were examined based on the structure-activity relationship. It was suggested that the bioactivities may link to acyl ester groups in aloesin, together with those of aloesin-related compounds. However, investigations using the contact hypersensitivity response indicated a preventive effect of aloesin on the UV-B-induced immune suppression. Furthermore, aloesin inhibited tyrosine hydroxylase and dihydroxyphenylalanine (DOPA) oxidase activities of tyrosinase from normal human melanocyte cell lysates. These results show that aloesin prevents not only UV-B-induced immune suppression, but also could be a positive pigment-altering agent for cosmetic application. In preclinical study, aloe extract was investigated using phagocytosis and nitroblue tetrazolium chloride (NBT) reduction in adult bronchial asthma, and high molecular-weight materials, such as polysaccharide and glycoprotein fractions, were identified as active ingredients. The neutral polysaccharides, aloemannan and acemannan showed antitumor, antiinflammatory and immunosuppressive activities, and glycoprotein fractions with bradykinindegrading and cell proliferation-stimulating activities were identified from the nondialysate fraction of the gel part of Aloe species. Verectin fractionated from Aloe vera gel was examined biochemically and immunochemically, and verectin antibody was used in the appraisal of commercial Aloe vera gel products. It was reported that aloesin stimulates the proliferation of cultured human hepatoma SK-Hep 1 cells. Thus aloesin, related compounds, and high molecular-weight materials, such as aloemannan and verectin, may act in concert to exert therapeutic properties for wounds, burns and inflammation. The biodisposition of fluoresceinylisothiocyanate (FITC)--labeled aloemannan (FITC-AM) with the homogenate from some organs in mice was demonstrated, and FITC-AM was metabolized to a smaller molecule (MW 3000) by the large intestinal microflora in feces. The modified aloe polysaccharide (MW: 80000) with cellulase under restricted conditions, immunologically stimulated the recovery of UV-B-induced tissue in jury. Thus the modified polysaccharides of aloemannan, together with acemannan (MW: about 600000), are expected to participate in biological activity following oral administration. The effects of tanshinone VI, a diterpenoid isolated from Salvia miltiorrhiza, on the heart are reviewed. First, the effects on the posthypoxic recovery of contractile function of perfused rat hearts were examined. Hypoxia/reoxygenation induced a release of purine nucleosides and bases (ATP metabolites) and resulted in little recovery of contractile force of reoxygenated hearts. Pretreatment of the perfused heart with 42 nM tanshinone VI under hypoxic conditions attenuated the release of ATP metabolites during hypoxia/reoxygenation. Treatment with tanshinone VI enhanced the posthypoxic recovery of myocardial contractility. These results show that tanshinone VI may protect the heart against hypoxia/reoxygenation injury and improve the posthypoxic cardiac function. Second, the effects of tanshinone VI on in vitro myocardial remodeling were examined. Cardiomyocytes and cardiac fibroblasts were isolated from neonatal rat hearts, and simultaneously prepared insulin-like growth factor-1 (IGF-1) induced the hypertrophy of cardiomyocytes. IGF-1 increased the collagen synthesis of cardiac fibroblasts, that is, in vitro fibrosis. The hypertrophy of cardiomyocytes was attenuated in the presence of tanshinone VI in the culture medium. The fibrosis of cardiac fibroblasts was decreased by treatment with tanshinone VI. When tanshinone VI was added to cardiac fibroblast-conditioned medium, the medium-mediated hypertrophy of cardiomyocytes was also attenuated. These results show that tanshinone VI may attenuate in vitro cardiac remodeling. The series of studies has shown that tanshinone VI protects the myocardium against hypoxia/reoxygenation injury and attenuates progression of in vitro myocardial remodeling, suggesting that tanshinone VI is a possible agent for the treatment of cardiac disease with contractile failure.

Protective effect of aloe extract against the cytotoxicity of 1,4-naphthoquinone in isolated rat hepatocytes involves modulations in cellular thiol levels

Aloe is a familiar ingredient in a wide range of health care and cosmetic products and has been reported to possess various physiological effects, antioxidative, anticarcinogenic, antiinflammatory and laxative. Aloe has also been reported to have an effect on liver function. The cytoprotective effect of aloe extract against 1,4-naphthoquinone-induced hepatotoxicity was evaluated in primary cultured rat hepatocytes. After exposure to 1,4-naphthoquinone (100 microM), a decrease in cell viability measured as >60% lactate dehydrogenase depletion was induced. Cellular glutathione (GSH) and protein-SH levels were also significantly decreased in a time-dependent manner. However addition of aloe extract resulted in a dose-dependent improvement of these effects. This cytoprotective effect of aloe could be attributed to its inhibition of GSH and protein-SH depletions. The effect of the aloe extracts were also dose-dependent. Addition of diethyl maleate (1 mM), a cellular glutathione-depleting agent, to hepatocytes treated with both 1,4-naphthoquinone and aloe extract, induced depletion of GSH, but did not affect protein-SH or lactate dehydrogenase. These results suggest that the 1,4-naphthoquinone-induced toxicity in rat hepatocytes was inhibited by aloe extract, and that this protective effect was due to the maintenance of cellular thiols, especially protein-SH.

Synthesis of C-mannopyranosylphloroacetophenone derivatives and their anomerization

The reaction of 2,3,4-tri-O-benzyl-alpha-L-rhamnopyranosyl fluoride (6-deoxy-2,3,4-tri-O-benzyl-alpha-L-mannopyranosyl fluoride) with 2,4-dibenzylphloroacetophenone, in the presence of boron trifluoride.diethyl etherate, afforded both the 3-C-alpha-L- and the 3-C-beta-L-rhamnopyranosylphloroacetophenone derivatives. The 3-C-alpha-L-rhamnoside was produced as a major product, while the 3-C-beta-L-rhamnoside was produced as a minor product via anomerization of the 3-C-alpha-L-rhamnoside. Alternatively, the reaction of 2,3,4,6-tetra-O-benzyl-alpha-D-mannopyranosyl fluoride with 2,4-dibenzylphloroacetophenone afforded both the 3-C-alpha-D- and the 3-C-beta-D-mannnopyranosylphloroacetophenone derivatives under identical conditions. The 3-C-beta-D-mannoside was produced as a major product via anomerization of the 3-C-alpha-D-mannoside during the reaction. These differences in composition result apparently from the magnitude of the 1,3-diaxial interactions between the C-3 and C-5 positions in these sugar moieties.

Constituents of Aloe rubroviolacea

The isolation of three C-glycosyl chromones, four anthraquinones and a mixture of phytosterols from the leaves of Aloe rubroviolacea was reported.

The conversion of 3-C-beta-D-galactopyranosyl phloroacetophenone to a spiroketal derivative

Treatment of 3-C-beta-D-galactopyranosylphloroacetophenone in hot water with a catalytic amount of p-toluenesulfonic acid afforded a spiroketal compound as the main product. The chirality of the spiro carbon of the product was R, which is the opposite of the spiroketal obtained by the conversion of 3-C-beta-D-glucopyranosyl phloroacetophenone under identical conditions. The structure was determined by 1H-1H COSY, 1H-13C COSY, NOESY and HMBC spectroscopy.

Isolation and identification of a phenolic antioxidant from Aloe barbadensis

A potent antioxidative compound has been isolated from a methanolic extract of Aloe barbadensis Miller using a combination of column and thin-layer chromatography. The antioxidant activity of this substance was similar to that of alpha-tocopherol as assessed in vitro using rat brain homogenates. On the basis of electrospray ionization and electron-impact ionization mass spectra in combination with reversed-phase, high-performance liquid chromatographic behavior, this compound has been identified as 8-C-beta-D-[2-O-(E)-coumaroyl]glucopyranosyl-2-[2-hydroxy]-propyl-7-methoxy-5-methylchromone.

Aloe vera leaf gel: a review update

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

Antifungal effects of different plant extracts and their major components of selected aloe species

Different extracts of both fresh and dry leaves of Aloe eru A. Berger, A. vera L. Webb & Berth and A. arborescens Mill. were screened for their antifungal activity against Aspergillus niger, Cladosporium herbarum and Fusarium moniliforme. The toxicity of the isolated pure components were evaluated on the tested fungi. A comparative chromatographic study was performed to differentiate between natural components existing in various fractions and extracts of Aloe species and specific spray reagents were used for the detection of anthraquinones in the isolated components.