Mixture Of Glycosides Research Articles

Diversity-Oriented Synthesis of Steviol Glycosides.

With cheap and easily available mixtures of steviol glycosides as starting materials, a practical method for steviol acquisition has been developed, on the basis of which a facile, diversity-oriented, and economic protocol for the synthesis of structurally defined steviol glycosides was established. The novel approach is featured by the highly efficient glycosylation of sterically hindered and acid-sensitive steviol via orchestrated application of Yu glycosylation, Schmidt glycosylation, and PTC glycosylation. Hence, these high-intensity sweeteners and potential lead compounds for drug development are now readily accessible.

Effectivity of nanovaccine against tick-borne encephalitis

The tubular immunostimulating complex (Tl-complex) is a new nanoparticulate antigen delivery system, which was developed to enhance immunogenicity of different subunit antigens within anti-infectious vaccines and increase their economic efficacy and safety. TI-complexes are self-organized from mixture of triterpene glycosides from Cucumaria japonica, cholesterol and monogalactosyldiacylglycerol (MGDG) from marine macrophytes. MGDG plays role of lipid matrix for subunit protein antigen interrupted in TI-complexes. Microviscosity of MGDG was shown to influence the conformation and immunogenicity of protein antigen. Present work was aimed to study adjuvant effect of Tl-complexes on immunogenicity of chimeric protein antigen based on E protein domain III of tick-borne encephalitis (TBE) virus and OmpF porin of Yersinia pseudotuberculosis depending on MGDGs isolated from different marine algae and seagrass. It was shown that TI-complex including MGDG from Ulva lactuca was most effective. Immunization by chimeric antigen incorporated in TI-complexes provided a high level of animal protection in experimental infection with TBE. Thus, the proposed construction is promising for the development of vaccines against TBE.

Comparison between Two Solid-Liquid Extraction Methods for the Recovery of Steviol Glycosides from Dried Stevia Leaves Applying a Numerical Approach

Stevia rebaudiana Bertoni is a perennial shrub belonging to the Asteraceae family. The leaves contain a mixture of steviol glycosides with extraordinary sweetening properties, among which the most important are stevioside and rebaudioside A. These components have a high sweetening power, which is about 300 times that of sucrose, and a negligible calorie content. However, their extraction and purification are not easy. In this paper, the extraction technique under cyclic pressure, known as rapid solid-liquid dynamic extraction (RSLDE), was compared using a Naviglio extractor (NE) with conventional maceration. The aim was to identify an efficient and economically viable method for obtaining high amounts of steviol glycosides in a short time. Furthermore, a numerical model was set up for the solid-liquid extraction process of value-added compounds from natural sources. Several parameters must be evaluated in relation to the characteristics of the parts of the plant subjected to extraction. Therefore, since diffusion and osmosis are highly dependent on temperature, it is necessary to control the temperature of the extraction system. On the other hand, the final aim of this work was to provide a scientific and quantitative basis for RSLDE. Therefore, the results obtained from stevia extracts using the corresponding mathematical model allowed hypothesizing the application of this model to the extraction processes of other vegetable matrices.

Breviscapine ameliorates CCl4‑induced liver injury in mice through inhibiting inflammatory apoptotic response and ROS generation.

Acute liver injury is characterized by fibrosis, inflammation and apoptosis, leading to liver failure, cirrhosis or cancer and affecting the clinical outcome in the long term. However, no effective therapeutic strategy is currently available. Breviscapine, a mixture of flavonoid glycosides, has been reported to have multiple biological functions. The present study aimed to investigate the effects of breviscapine on acute liver injury induced by CCl4 in mice. C57BL/6 mice were subjected to intraperitoneal injection with CCl4 for 8 weeks with or without breviscapine (15 or 30 mg/kg). Mice treated with CCl4 developed acute liver injury, as evidenced by histological analysis, Masson trichrome and Sirius Red staining, accompanied with elevated levels of alanine aminotransferase and aspartate aminotransferase. Furthermore, increases in pro-inflammatory cytokines, chemokines and apoptotic factors, including caspase-3 and poly(ADP ribose) polymerase-2 (PARP-2), were observed. Breviscapine treatment significantly and dose-dependently reduced collagen deposition and the fibrotic area. Inflammatory cytokines were downregulated by breviscapine through inactivating Toll-like receptor 4/nuclear factor-κB signaling pathways. In addition, co-administration of breviscapine with CCl4 decreased the apoptotic response by enhancing B-cell lymphoma-2 (Bcl-2) levels, while reducing Bcl-2-associated X protein, apoptotic protease activating factor 1, caspase-3 and PARP activity. Furthermore, CCl4-induced oxidative stress was blocked by breviscapine through improving anti-oxidants and impeding mitogen-activated protein kinase pathways. The present study highlighted that breviscapine exhibited liver-protective effects against acute hepatic injury induced by CCl4 via suppressing inflammation and apoptosis.

Safety of the proposed amendment of the specifications of the food additive steviol glycosides (E 960).

The EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS) provides a scientific opinion on the safety of proposed amendment of the specifications of the food additive steviol glycosides (E 960). The applicant asked to amend the existing EU specifications for steviol glycosides to allow for the inclusion of all steviol glycosides identified in Stevia rebaudiana Bertoni leaves, including both ‘major’ and ‘minor’ glycosides, that may comprise the assay value of not less than 95% total steviol glycosides. According to the applicant, all steviol glycosides are subject to microbial metabolism in a similar manner, ultimately generating the common primary metabolite steviol. There are uncertainties on the rate and extent of the metabolism of different steviol glycosides to steviol in the evidence provided and they did not allow the Panel to endorse the applicant's argumentation that all steviol glycosides generate the common metabolite steviol when subjected to microbial metabolism under realistic conditions. The available information was not sufficient to assess the safety of the proposed amendment of the specifications for E 960 and the conclusions on the previous assessments on steviol glycosides cannot be extrapolated to any other mixture of steviol glycosides (containing not less than 95% of any steviol glycosides) extracted from S. rebaudiana Bertoni leaves. Therefore, the Panel concluded that the submitted data were insufficient to assess the safety of proposed amendment of the specifications of the food additive steviol glycosides (E 960).

Synthesis of an IS and Steviol Glycoside Analysis by a Validated Internal Standard Method

The internal standard (IS) method is the best method for the analysis of samples, as it is independent of errors in injection volume, changes in sample volumes, and changes in sensitivity of the detector, etc. Use of an internal standard allows for the correction of losses due to sample clean-up of complex samples. An ideal IS is a compound that has properties very similar to, and that behaves as the compounds to be analysed. Ideally, only in the last step of analysis (HPLC), the IS should be well separated from the compounds of the mixture to be analysed. After testing several existing compounds with negative results, we decided to synthesise the 19-O-β-D-galactopyranosyl-13-O-β-D-glucopyranosyl-steviol as IS. This is the 19-galactosyl ester of steviolmonoside (13-O-β-D-glucopyranosyl-steviol). The IS was made according to published methods. Steviolmonoside (SM) was made from purified commercial rubusoside (Rub) by refluxing it in 10% KOH for 2 h. SM was precipitated and crystallized from MeOH. The hydroxyls of the glucose unit of SM were protected by acetylation. The acetylated SM was crystallized from acetone and dissolved in 1,2-dichloroethane. Then Ag2CO3 on Celite and tetra-acetylated galactopyranosyl bromide were added and the mixture was refluxed for 2 h. After cooling, BaO in MeOH was added to remove the acetyl groups. The 1,2-dichloroethane fraction was then extracted three times with equal volumes of water and the water fraction containing the IS was further purified on a C18 flash chromatography column. Traces of unreacted SM were removed by preparative HPLC on an Alltima C18 column (250 mm × 22 mm, particle size 10 μm) with AcCN:water (35:65, 20 ml/min). Detection was at 210 nm (KNAUER, “Smartline” UV detector 2500). The collected IS fraction from the HPLC was completely dried. Mixtures of steviol glycosides (SVglys) containing IS could be purified over SPE cartridges without change of the SVgly over IS ratio. The calibration curves for rebaudioside A (RebA) and stevioside (ST) were linear between 0.012 and 0.95 and between 0.013 and 1.13 mM for RebA and ST, respectively. The accuracy was checked by the standard addition method. It was concluded that the IS method gives an excellent precision and accuracy.

In Vitro Antidiabetic Effects of Isolated Triterpene Glycoside Fraction from Gymnema sylvestre.

A triterpene glycoside (TG) fraction isolated and purified from ethanolic extract of Gymnema sylvestre (EEGS) was investigated for blood glucose control benefit using in vitro methods. The HPLC purified active fraction TG was characterized using FTIR, LC-MS, and NMR. The purified fraction (TG) exhibited effective inhibition of yeast α-glucosidase, sucrase, maltase, and pancreatic α-amylase with IC50 values 3.16 ± 0.05 μg/mL, 74.07 ± 0.51, 5.69 ± 0.02, and 1.17 ± 0.24 μg/mL, respectively, compared to control. TG was characterized to be a mixture of triterpene glycosides: gymnemic acids I, IV, and VII and gymnemagenin. In vitro studies were performed using mouse pancreatic β-cell lines (MIN6). TG did not exhibit any toxic effects on β-cell viability and showed protection against H2O2 induced ROS generation. There was up to 1.34-fold increase in glucose stimulated insulin secretion (p<0.05) in a dose-dependent manner relative to standard antidiabetic drug glibenclamide. Also, there was further one-fold enhancement in the expression of GLUT2 compared to commercial standard DAG (deacylgymnemic acid). Thus, the present study highlights the effective isolation and therapeutic potential of TG, making it a functional food ingredient and a safe nutraceutical candidate for management of diabetes.

HPLC-MS profiling of the multidrug-resistance modifying resin glycoside content of Ipomoea alba seeds

High performance liquid chromatography profiling with mass spectrometry detection was applicable to identify known and novel multidrug-resistance glycolipid inhibitors from the complex resin glycosides mixture of Ipomoea alba L., Convolvulaceae, seeds. Albinosides X and XI were purified by recycling liquid chromatography and their structural elucidation was accomplished by nuclear magnetic resonance. Albinoside XI exerted a strong potentiation of vinblastine susceptibility in multidrug-resistant human breast carcinoma cells.

Breviscapine (BVP) inhibits prostate cancer progression through damaging DNA by minichromosome maintenance protein-7 (MCM-7) modulation

Naturally occurring compounds are reported as effective candidates for prevention and treatment of various cancers. Breviscapine (BVP) is a mixture of flavonoid glycosides, derived from the Chinese herbs. Previous researches have indicated that BVP has comprehensive pharmacological functions. However, little is known about whether BVP has preventive effects on human prostate cancer. Here, we attempted to explore if BVP inhibits human prostate cancer in vitro and in vivo in a comprehensive manner. We found that BVP triggered cytotoxicity in prostate cancer cell lines dose-dependently. BVP-induced DNA damage caused the cell cycle arrest and apoptosis and further induced cell death. High expression of MCM-7 was reduced in BVP-treated cancer cells and tumor tissues, and also the DNA damage response marker of γH2AX is down-regulated by BVP, associated with MCM-7 expression through regulating retinoblastoma protein (Rb) and checkpoint control proteins expression. Additionally, BVP induced apoptotic response in prostate cancer cells and tumors via activating Caspase-3 and PARP. In vivo studies indicated that BVP impeded tumor growth in xenograft animal models. In conclusion, our data indicates that breviscapine (BVP) can be further explored for its potential, which might be used in human prostate cancer therapeutics.

Comparative Study on the Antivirus Activity of Shuang–Huang–Lian Injectable Powder and Its Bioactive Compound Mixture against Human Adenovirus III In Vitro

Shuang–Huang–Lian injectable powder (SHL)—a classical purified herbal preparation extracted from Scutellaria baicalensis, Lonicera japonica, and Forsythia suspense—has been used against human adenovirus III (HAdV3) for many years. The combination herb and its major bioactive compounds, including chlorogenic acid, baicalin, and forsythia glycosides A, are effective inhibitors of the virus. However, no comprehensive studies are available on the antiviral effects of SHL against HAdV3. Moreover, it remains unclear whether the mixture of chlorogenic acid, baicalin, and forsythia glycosides A (CBF) has enhanced antiviral activity compared with SHL. Therefore, a comparative study was performed to investigate the combination which is promising for further antiviral drug development. To evaluate their antivirus activity in parallel, the combination ratio and dose of CBF were controlled and consistent with SHL. First, the fingerprint and the ratio of CBF in SHL were determined by high performance liquid chromatography. Then, a plaque reduction assay, reverse transcription polymerase chain reaction (PCR), real-time polymerase chain reaction (qPCR), and enzyme-linked immunosorbent assay (ELISA) were used to explore its therapeutic effects on viral infection and replication, respectively. The results showed that SHL and CBF inhibited dose- and time-dependently HAdV3-induced plaque formation in A549 and HEp-2 cells. SHL was more effective than CBF when supplemented prior to and after viral inoculation. SHL prevented viral attachment, internalization, and replication at high concentration and decreased viral levels within and out of cells at non-toxic concentrations in both cell types. Moreover, the expression of tumor necrosis factor alpha (TNF)-α, interleukin (IL)-1ß, and IL-6 was lower and the expression of interferon (IFN)-γ was higher in both cell types treated with SHL than with CBF. In conclusion, SHL is much more effective and slightly less toxic than CBF.

Identification of Ellagic Acid Rhamnoside as a Bioactive Component of a Complex Botanical Extract with Anti-biofilm Activity.

Staphylococcus aureus is a leading cause of hospital-acquired infections. It is listed among the top “serious threats” to human health in the USA, due in large part to rising rates of resistance. Many S. aureus infections are recalcitrant to antibiotic therapy due to their ability to form a biofilm, which acts not only as a physical barrier to antibiotics and the immune system, but results in differences in metabolism that further restricts antibiotic efficacy. Development of a modular strategy to synthesize a library of phenolic glycosides allowed for bioactivity testing and identification of anti-biofilm compounds within an extract of the elmleaf blackberry (Rubus ulmifolius). Two ellagic acid (EA) derivatives, EA xyloside and EA rhamnoside, have been identified as components of the Rubus extract. In addition, EA rhamnoside has been identified as an inhibitor of biofilm formation, with activity comparable to the complex extract 220D-F2 (composed of a mixture of EA glycosides), and confirmed by confocal laser scanning microscopy analyses.

Optimization of Yield for Extraction of an Essential Oil from Cinnamon Using Microwave-Assisted Extraction

Sicklepod (Senna obtusifolia L.) is synonymous both with Cassia tora L. and Cassia obtusifolia L.). It is usually viewed as a noxious weed in crop fields in southeastern United States. This plant, however, has a long history of use in traditional medicine in oriental countries. It is a prolific seed producer the constituents of which include: polysaccharides, proteins, highly colored low fat content and many phenolic compounds. The phenolic components are usually described as toxic, although recent literature shows many of these to exhibit potent therapeutic properties for human health. Pursuant to this as part of our continuing interest in the plant, we have expanded our study of the seed by extracting a mixture of anthraquinone and naphthopyrone glycosides from S. obtusifolia seed obtained from North Carolina. A survey of the composition of the extract was affected using High Performance Liquid Chromatography-Electrospray Ionization-Mass Spectrometry (HPLC-ESI-MS) with a variety of collision induced dissociation (CID) experiments. The major constituents of the mixture produced HPLC-ESI-MSn data consistent with: chrysophanic acid tetraglycoside; rubrufusarin and toralactone di-, tri- and tetraglycosides; torachrysone ester, di-, tri-, tetra- and pentaglycosides and cassialactone tetraglycoside. The naphthopyrone glycosides and related phenolic compounds in the seed are value-added medicinal co-products to the galactomannan polysaccharides of S. obtusifolia. FT-IR spectra of the mixture corroborate the chromatographic information obtained of the mixture of anthraquinone glycosides.

Glycosides from Stevia rebaudiana Bertoni Possess Insulin-Mimetic and Antioxidant Activities in Rat Cardiac Fibroblasts.

Stevia rebaudiana Bertoni is a shrub having a high content of sweet diterpenoid glycosides in its leaves, mainly stevioside and rebaudioside A, which are used as noncaloric, natural sweeteners. The aim of this study was to deepen the knowledge about the insulin-mimetic effect exerted by four different mixtures of steviol glycosides, rich in stevioside and rebaudioside A, in neonatal rat cardiac fibroblasts. The potential antioxidant activity of these steviol glycosides was also assessed, as oxidative stress is associated with diabetes. Likewise the insulin effect, steviol glycosides caused an increase in glucose uptake into rat fibroblasts by activating the PI3K/Akt pathway, thus inducing Glut4 translocation to the plasma membrane. The presence of S961, an insulin antagonist, completely abolished these effects, allowing to hypothesize that steviol glycosides could act as ligands of the same receptor engaged by insulin. Moreover, steviol glycosides counteracted oxidative stress by increasing reduced glutathione intracellular levels and upregulating expression and activity of the two antioxidant enzymes superoxide dismutase and catalase. The present work unravels the insulin-mimetic effect and the antioxidant property exerted by steviol glycosides, suggesting their potential beneficial role in the cotreatment of diabetes and in health maintenance.

Anthenosides L-U, Steroidal Glycosides with Unusual Structural Features from the Starfish Anthenea aspera.

Ten new polyhydroxysteroidal glycosides, anthenosides L-U (1-10), with rare positions of carbohydrate fragment attachments, were isolated from the starfish Anthenea aspera. The structures of 1-10 were established by NMR and ESIMS techniques as well as by chemical transformations. The unoxidized Δ22-24-nor-cholestane (1), (24S)-Δ22-24-methylcholestane (2-5), and Δ22-cholestane (7) side chains of the steroidal aglycons, 3-O-methyl-β-d-galactofuranosyl residue (2, 8), and 5α-cholest-8(14)-ene-3α,7β,16α-trihydroxysteroidal nucleus (9, 10) have not been found previously in starfish polar steroidal compounds. The mixture of glycosides 9 and 10 showed hemolytic activity with an EC50 = 8 μM. Compound 4 at a dose of 10 μM exhibited a potential immunomodulatory action, decreasing by 24% the intracellular ROS content in RAW 264.7 murine macrophages, induced by pro-inflammatory endotoxic lipopolysaccharide from E. coli.

Effect of a mixture of diosmin, coumarin glycosides, and triterpenes on bleeding, thrombosis, and pain after stapled anopexy: a prospective, randomized, placebo-controlled clinical trial.

We evaluated the efficacy of oral administration of a mixture of diosmin, coumarin glycosides, and Centella asiatica (Venoplant®) in preventing bleeding, pain, and thrombosis of internal and external hemorrhoids after stapled anopexy (SA). SA was conducted in 182 patients with third-degree hemorrhoids. Preoperatively, patients were randomized evenly into two groups. Group A patients were administered Venoplant for 30days post-SA, and group B received a placebo for 30days post-SA. Patients received paracetamol for postoperative pain. Visit (v)1, v2, and v3 took place 7, 15, and 30days postoperatively, respectively; bleeding (clinical examination), visual analog scale (VAS), thrombosis (clinical examination), and pain (paracetamol dosage, VAS) were evaluated. At v1, v2, and v3, the numbers of patients with bleeding in groups A and B were 21 and 46, 3 and 25, and 1 and 5, respectively (p<0.05). At v1, v2, and v3, the numbers of patients in groups A and B with thrombosed internal hemorrhoids were 3 and 13, 2 and 11, and 1 and 8, respectively (p<0.05). The number of patients who took at least one paracetamol tablet was similar in both groups at v1 but was significantly greater in group B than group A at v2 and v3 (p<0.05); pain VAS scores were equivalent at v1 and significantly greater in group B than group A at v2 and v3 (p<0.05). Venoplant effectively reduced bleeding after SA, decreased the incidence of thrombosed internal hemorrhoids, and decreased postoperative pain.

Recombinant α-l-rhamnosidase from Aspergillus terreus in selective trimming of α-l-rhamnose from steviol glycosides

Although stevioside is the most abundant sweetener in Stevia rebaudiana leaves, other steviol glycosides determine its taste. The steviol glycosides dulcoside A and dulcoside B both feature a terminal α-l-rhamnose residue and are the bitterest compounds in steviol glycoside mixtures. Here we show that Aspergillus terreus α-l-rhamnosidase specifically hydrolyses the glycosidic linkage of dulcoside A, and converts it to rubusoside. The constitutive expression of α-l-rhamnosidase in Pichia pastoris and Kluyveromyces lactis achieved high protein yields of up to 17.6U/mL and 30.6U/mL, respectively. During a 12-h biotransformation, the dulcoside A from crude leaf extracts was completely converted into rubusoside. There was no hydrolytic activity against dulcoside A analogues. This process therefore offers a promising approach for reducing the bitterness of steviol glycoside mixtures.

Validation of an HPLC method for direct measurement of steviol equivalents in foods

Steviol glycosides are intense natural sweeteners used in foods and beverages. Their acceptable daily intake, expressed as steviol equivalents, is set at 0–4mg/kg body weight. We report the development and validation of a RP-HPLC method with fluorometric detection of derivatized isosteviol, formed by acid hydrolysis of steviol glycosides. Dihydroisosteviol was used as an internal standard. Using this method, the amount of steviol equivalents in commercial steviol glycoside mixtures and different foods can be directly quantified. The method was successfully tested on strawberry jam, low-fat milk, soft drink, yogurt and a commercial mixture of steviol glycosides. Calibration curves were linear between 0.01 and 1.61mM steviol equivalents, with a quantification limit of 0.2nmol. The % RSD of intra-day precision varied between 0.4% and 4%, whereas inter-day precision varied between 0.4% and 5%, for high and medium concentrations, and between 3% and 8% for low concentrations. Accuracy of the analysis varied between 99% and 115%.

AuCl3– and AuCl3–Phenylacetylene‐Catalyzed Glycosylations by Using Glycosyl Trichloroacetimidates

AbstractGlycosylations of armed and disarmed trichloroacetimidate‐based glycosyl donors were carried out by using the AuCl3–phenylacetylene relay catalyst system. The effectiveness of this catalytic system was also compared with that of using AuCl3 alone as a catalyst. Glycosylations with these catalysts proceeded efficiently at room temperature within 5–45 min. Excellent diastereoselectivity was obtained for the glycosylation of 2‐O‐acetyl‐protected disarmed glycosyl donors, whereas armed glycosyl trichloroacetimidates gave rise to a mixture of anomeric glycosides. Acid‐sensitive nucleophiles such as Fmoc‐serine tert‐butyl ester or Fmoc‐threonine tert‐butyl ester successfully underwent the glycosylations, albeit in moderate yields, under mild conditions at room temperature.

Identification of maloyl glucans from Euphorbia tirucalli by ESI-(−)-FT-ICR MS analyses

Euphorbia tirucalli aerial parts are popularly used in Brazil for cancer treatment. The elution of the aqueous extract of the plant on silica gel C-18 cartridge furnished a water-soluble fraction, which was analyzed directly into the electrospray ionization (ESI) source combined with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and characterized as a mixture of malic acid glycosides 1–5. The compounds were detected in their deprotonated form [M−H]−, where their exact mass (mass error lower than 1ppm), molecular formula (CnHhOo), double bond equivalent (DBE) and connectivity were determined from ESI-(−)-MS and ESI-(−)-MS/MS experiments. The presence of malic acid and glucose, as part of the structures, could originate from crassulacean acid metabolism (CAM) of the plant.

Development of stomata in Hordeum vulgare L. under the influence of oleander glycosides and colchicine

The effect of aqueous solutions of a 0.1 per cent mixture of oleander glycosides and of 0.1 and 0.5 per cent colchicine on the growth of seedlings, and particularly on the development of stomata was investigated in &lt;i&gt;Hordeum vulgare&lt;/i&gt; L. The compounds were found not to penetrate with the same readiness through the coleoptile: glycosides passed very slowly, while colchicine rapidly. Growth inhibition of seedlings increased with the concentrations of the solutions applied, the time of incubation and the degree of damage to the coleoptile. Colchicine and glycosides cause a similar type of disturbances in all cell divisions leading to the formation of stomata. Most numerous disturbances were noted in phase II. The cause of these disorders lies in damage to the karyokinetic sipindle and abnormal cytokinesis. As a result are formed the stomata with a changed number of guard cells or subsidiary cells, their shape is changed and sometimes also their orientation and the dimensions are reduced.