alpha-methyl-D-glucoside Research Articles

The stereoselective synthesis of biobased nonionic sugar surfactants (polyhydroxy surfactants), which are thought to be safer, more affordable, plentiful, biodegradable, biocompatible, and possess mildness and performance in formulation, is becoming increasingly popular as people become more aware of the potential negative effects of conventional surfactants on the environment and human health. Reviewing the stereoselective synthesis of polyhydroxy surfactants is the objective of this article. Additionally, it emphasizes the synthesis and application of sugar‐based surfactants in everyday life, as well as their description and the influence of outside factors. A thorough assessment of the literature on biobased polyhydroxy surfactants including alkyl polyglycosides, sorbitol esters, sucrose esters, fatty acid glucamides, and methyl glucosides was studied for methodology. The characterization of the surfactants shows an exponential increase in electrical conductivity when there is an increase in the water volume fraction. The surface tension also showed a linear relationship with surfactant concentration, such that as the concentration increases, the surface tension of the solution decreases. The effect of external parameters on polyhydroxy surfactants was also studied, which shows that increasing temperature favors micellization initiation at a lower concentration. Likewise, the micellar molecular weight and the hydration per unit mass of the surfactants decrease with an increase in the pH value. Evidence to further support these biobased surfactants as substitutes for their petrochemical counterparts is advantageous as worldwide legislation and user requirements for sustainability and safety expand.

Abstract Carbon solid acid catalysts play a very important role in the high value‐added utilization of biomass and its derivatives. A series of carbon‐based solid acids catalysts were prepared by high‐temperature carbonization, hydrothermal sulfonation and metal impregnation using cellulose as the carbon source. The prepared catalysts were characterized by XRD, Raman, SEM‐EDX, BET, FT‐IR, XPS, ICP‐OES and the total acid density of the catalyst was tested by acid‐base titration. The experimental and characterization results showed that the large pore size, suitable specific surface area and acid density were the main reasons for the good catalytic performance of the catalyst 300‐AC‐Cr‐SO3H. Under the optimal reaction conditions, the conversion of glucose was 99.6 % and the yield of the products methyl levulinate and levulinic acid was 43.1 %. The study of the intermediates revealed that glucose is preferentially converted to methyl glucoside in methanol solution. In addition, the catalyst maintains good stability after three cycles.

The three isolates were isolated from the methanolic extract of Abrus precatorius seeds by column chromatography using silica gel 60-120 mesh as the adsorbent and methanol as the mobile phase. The isolated compounds are further purified by TLC. The compounds that have the same RF value are combined. The crude extract was named CMME. The isolated compounds named CMME I, CMME II, and CMME III are first-eluted, second, eluted, and third-eluted compounds respectively. The isolated compounds were characterized by LC-MS, 1H NMR, and 13C NMR. The compound I was found to be (4,6-O-Benzylidene) methyl-alpha D-glucopyranoside, m/z282.3923, molecular formula C14H18O6. The compound II was found to be Isoflavone base + 20, O-Malonyl Hex, m/z 502.42801, molecular formula C24H22O12. The compound III was found to be 3-Carboxy-1-methyl pyridinium chloride, m/z 173.6, molecular formula C7H8ClNO2.

Four different solvents, ethyl acetate, ethanol, petroleum ether, and hexane, were used for the multistage solvent extraction of rose concrete oil from the aromatic plant species of Rosa x damascena. The components present in the concrete oils were analyzed using Gas Chromatography-Mass Spectrometer. After the multistage solvent extraction process, the solvent was removed by using a rotary vacuum evaporator. Methyl alpha d-glucopyranoside, 5-hydroxy methyl furfural, 2,3-butanediol, and ethyl-d glucopyranoside were the major components identified using ethyl acetate ethanol, hexane, and petroleum ether as a solvent, respectively. The phenyl ethyl alcohol and 5-hydroxymethyl furfural were identified as the repeated components in all four solvents. The solvent ethanol showed a different composition when compared to the other three solvents. A high yield was obtained when ethanol was used as a solvent. The type of solvent used significantly impacts the compositions of the concrete oil of Rosa x damascena.

Methyl levulinate was selectively formed from glucose and methanol over a copper modified Beta zeolite bifunctional catalyst at 180 °C under argon atmosphere. The selectivity to methyl levulinate substantially exceeded previously reported in the open literature results. The copper modification was done through an ion-exchange method using a solution of copper nitrate, followed by drying and calcination of the catalyst. Copper modification changed the distribution of acid sites namely, less Brønsted and more Lewis sites were observed with FTIR using pyridine adsorption. Application of the proton form H-Beta-25 gave the methyl levulinate yield of ca. 89%, which could be elevated with the addition of copper, as the apparent selectivity exceeds 99%, assuming that methyl glucosides are eventually transformed to methyl levulinate. The non-acidic Cu/SiO2 catalyst was completely inactive in methyl levulinate formation. Metal modification of Beta zeolite with Sn and Zn did not perform as well as Cu in the formation of methyl levulinate during glucose transformation.

The prevalence of treatment failures from dietary patterns and oral medications associated with diabetes have generated adverse effects and are oftentimes expensive. Recently, food-based therapies such as Rauwolfia serpentina (serpentina) and Costus igneus (insulin plant) have been received much attention due to the urge for an alternative and safe solution against diabetes. Thus, the hypoglycemic effects of serpentina and insulin plant leaf crude extracts were determined on the blood glucose level of test rats. Twenty-four alloxan-induced male albino rats were subjected to this experimental study distributed into six groups in a completely randomized design. The negative control (NEG) comprised of diabetic rats receiving no treatment; while the positive control (MET) comprised of diabetic rats treated with metformin; experimental groups include IN1X and IN2X for the diabetic rats treated with extracts of insulin plant leaves administered once and twice daily and SER1X and SER2X for the diabetic rats treated with extracts of serpentina leaves administered once and twice daily. Results of the study revealed that both serpentina and insulin plant leaves crude extract demonstrated hypoglycemic effects due to the presence of zinc that potentiated insulin action. Further, the insulin plant improved glucose and insulin levels due to quercetin which reduced oxidative stress and protects DNA damage, β-amyrin and β-L-arabinose methyl glucoside which builds-up insulin for glucose metabolism. The presence of significant phytochemical contents in the insulin plant has been attributed to the stimulation of β cells. In conclusion, insulin plant leaf crude extract elucidated better hypoglycemic activity than the serpentina plant leaf crude extract in the blood glucose levels of alloxan-induced diabetic rats.

Biosynthesis of methyl glucoside and its antibacterial activity against Staphylococcus aureus and Escherichia coli

The specific type of acidity associated with the given metal trifloromethanesulfonates (Brønsted or Lewis acidity) dramatically influences the course of reactions, and it is possible to select for disaccharides, fructose, methyl glucosides, or methyl levulinate. Glucose is transformed into a range of value-added molecules in water and methanol under the action of acidic metal triflates as catalysts, including their analogous Brønsted acid-assisted or Brønsted base-modified systems. A systematic study is presented of a range of metal triflates in methanol and water, pinning down the preferred conditions to select for each product.

Ball milling for cellulose depolymerization and alcoholysis to produce methyl levulinate at mild temperature

The feasibility of separating small molecular organic compounds in the aqueous fraction of methyl bio-oils (AFMBO) using nanofiltration (NF) and reverse osmosis (RO) membranes was studied. Four kinds of commercially available NF and RO membranes were studied preliminarily by using model solutions (aqueous solution of methyl glycosides and glycerol). The membrane module was spiral wound, which is a more suitable format for industrialization than the flat-sheet format for dead-end filtration. The NF400-600 membrane exhibited the best separation performance; the permeate flux was 48.6 L/(m2·h), the methyl glucosides (MEG) rejection ratio was 95.4%, and the transmission of glycerol was 81.0% with an initial concentration of 10 g/L (0.4 MPa, 45 ºC). Compared with the model solution, the NF performance of AFMBO, which included permeate flux, rejection of MEG, transmission of glycerol, and separation of the other components in AFMBO, was investigated. The more complex constituents of AFMBO led to NF400-600 permeability and separating property decline compared with the model solution in the same operating conditions; meanwhile more serious and even irreversible membrane fouling occurred. This research provided a reference for membrane separation industrial feasibility and application of AFMBO.

The first triple-functional polyoxometalate Cs10.6[H2.4GeNb13O41] (CsGeNb) was evaluated for its catalytic activity in production of methyl levulinate (ML) from biomass substrates in methanol. Higher conversion of cellulose (86.0%) and higher yield of ML (53.0%) were obtained under optimized reaction conditions of 0.1 g of cellulose, 0.04 mmol of catalyst, and 6 mL of methanol at 165 °C for 10 h, due to its mixed Bronsted acid sites, Lewis acid sites, and base sites, being measured for the first time. Reaction intermediates in methanolysis of fructose, glucose, and cellulose provided some insight into the reaction pathways, while methyl glucoside and methyl fructoside (MF) were key intermediates generated by Bronsted acid and Lewis acid or base sites. Assisted by microwave irradiation, the efficiency could be improved to 55.4% yield of ML within 3 h. Meanwhile, CsGeNb acted as a heterogeneous catalyst through six recycles without loss of activity.

Abstract Conversion of lignocellulose into useful chemicals is an important research topic in the area of biomass utilization. In this study, microcrystalline cellulose (MC) was dissolved in a mixed-solvent system containing the ionic liquid (IL) 1-allyl-3-methylimidazolium chloride ([Amim]Cl) and N-methyl-pyrrolidone (NMP), and the cellulose was directly converted into methyl glucoside (MG) by acid-catalyzed methanolysis aided by microwave irradiation (μWIr). Under moderate reaction temperature and pressure, and in the presence of acetyl chloride/methanol (in situ formed HCl) as an acid catalyst, MG was obtained in a 42% yield. In contrast, in the absence of either IL or μWIr, the MG yield was only 5 or 21%, respectively. Both μWIr and the dissolution of cellulose in IL were quite effective for the conversion of cellulose into MG.

Abstract The efficient alcoholysis of cellulose to monosaccharide is of great importance to produce fuels and fine chemicals from renewable feedstocks. In this work, the conversion of cellulose into methyl glucosides was investigated by combining the pretreatment process of the ionic liquid 1‐allyl‐3‐methylimidazolium chloride ([Amim]Cl) and the subsequent alcoholysis catalyzed by the heteropolyacid H3PW12O40. The X‐ray diffraction characterization of [Amim]Cl‐pretreated cellulose shows that the pretreatment process could transform cellulose I to cellulose II resulting in the loss of crystalline structure. The subsequent alcoholysis of the pretreated cellulose catalyzed by H3PW12O40 proves to be a highly efficient way to convert cellulose to methyl glucosides in the medium of methanol. Under the optimized conditions of the [Amim]Cl pretreatment and alcoholysis reaction, the highest yield of methyl glucosides reaches up to 70.2 mass%, which is much higher than those previously published without pretreatment process.

A series of Lewis acid metals monosubstituted phosphotungstic acids HnPW11MO39 (HPWM, M = CuII, ZnII, CrIII, FeIII, SnIV, TiIV, and ZrIV; for Ti and Zr, the number of oxygen is 40) was evaluated in direct production of methyl levulinate (ML) from cellulosic biomass in a cascade reaction. One of the solid catalysts, H5PW11TiO40 (HPWTi), was found to be highly efficient for generation of ML from mono- or polysaccharides, reaching 51.3% ML yield directly from cellulose. And under microwave-assistance, the efficiency could be improved to a 62.6% ML yield within 2 h, which was almost the best result so far among reported solid catalysts. Identification of the reaction intermediates and the products provided some insight into the reaction mechanism and showed the requirement of certain Bronsted/Lewis acid ratio as 2.84/1 for HPWM. Moreover, the different metals in catalysts profoundly affected the Lewis or total acidity, and therefore, the catalytic activity and selectivity to ML or methyl glucosides (MG). HPWT...

Catalysis performance comparison of a Brønsted acid H2SO4 and a Lewis acid Al2(SO4)3 in methyl levulinate production from biomass carbohydrates

Flavonoid-rich foods intake has been associated with lower risk of non-communicable chronic diseases. Quercetin is the most abundant flavonoid in nature (fruits, vegetables, leaves and grains) as well as the most consumed flavonol. This study aims to investigate the potential effects of its conjugated form quercetin-3- O-glucoside (or isoquercetin) on glucose metabolism in rats and Caco-2 cells. To analyse the effect of quercetin-3- O-glucoside on postprandial hyperglycemia, an oral glucose tolerance test (OGTT) was conducted in Wistar rats. Additionally, Caco-2 cells were used to determine the effect of quercetin-3- O-glucoside (30 to 60 μM) on mRNA expression of genes involved in glucose uptake by RT-PCR. Thereby, in vivo studies demonstrated that quercetin-3- O-glucoside decreased blood glucose levels evaluated by OGTT in rats. Furthermore, in the presence of Na+, quercetin-3- O-glucoside inhibited methylglucoside (MG) uptake in enterocytes and both sodium dependent glucose transporter-1 (SGLT1)- and glucose transporter-2 (GLUT2)-mediated glucose uptake were downregulated in Caco-2 cells incubated with quercetin-3- O-glucoside. In summary, our results show that quercetin-3- O-glucoside improves postprandial glycemic control in rats and reduces sugar uptake in Caco-2 cells, possible by decreasing the expression of glucose transporters (SGLT1 and GLUT2) according to the results obtained through RT-PCR.

Levoglucosan, the major intermediate in cellulose pyrolysis, is stable up to around 500 °C in the gas phase. To study whether this stability is a characteristic property of levoglucosan, the gas-phase reactivity was compared with those of methyl α- and β-glucosides at 200–500 °C (residence time 1.2–2.0 s). The methyl glucosides decomposed even at 200 and 300 °C to form levoglucosan exclusively. This selective transglycosylation was explained with a concerted mechanism. Fragmentation of the glucosides forming C1–C3 carbonyl compounds started at 400 °C, a temperature lower than that of levoglucosan (500 °C). Thus, levoglucosan is a special carbohydrate that is stable in the gas phase, and the stability is explained by the steric hindrance of the bicyclic ring. Formation of the anhydrofuranose isomer and furans was negligible from the gas-phase pyrolysis of these compounds, suggesting that these are produced mainly from the molten-phase pyrolysis. These results show the roles of gas- and molten-phase reactions during carbohydrate pyrolysis, providing insights for upgrading biomass pyrolysis/gasification processes.

Epoxidized methyl or ethyl oleate were used as models of FAtty Methyl Esters to explore their functionalization via ring opening of the internal epoxide by alkyl glycosides. Overcoming solubility issues, medium to long‐chain alkyl glucosides gave better results than methyl glucoside. Er(OTf)3 turned out to catalyze at room temperature the selective formation of hydroxyalkylethers with good yields versus transesterification, despite the concomitant formation of fatty ketones. A brief scope of the reaction, using several available alkyl glycosides, suggests that the strategy can easily lead to new highly functionnalized amphiphilic compounds, potential precursors for biobased materials.Practical applications: Interested in the formation of original high‐value intermediates from renewable materials, we tackled the reaction of unprotected carbohydrates and unsaturated vegetal oils featuring an internal epoxide. After ring‐opening, the obtained highly functionalized polyols are potential precursors to produce new biobased polymers, lubricants or surface‐active compounds for high‐value cosmetic or biopharmaceutical formulations.The formation of hydroxyalkylethers from epoxidized fatty esters and alkyl glycosides are catalyzed by Er(OTf)3 at room temperature with good yields and high selectivity versus transesterification.

Alkyl glucosides surfactants are synthesized by a cascade process that involves the methanolysis of cellulose into methyl glucosides followed by the transacetalization with n-octanol. The first step was performed using methanol as solvent and acid catalysts (such as, inorganic acids, heteropolyacids, ionexchange resins, or modified carbon materials). Subsequently, long-chain alkyl glucosides are obtained in the second step by transacetalization, which involves the reaction of methyl glucosides with a fatty alcohol using the same acid catalyst. The overall process was performed under mild conditions. Amorphous sulfonated carbon catalyst achieved the best results for the complete conversion of cellulose in methanol at 200 °C with methyl α,β-glucopyranosides yields higher than 80 %. Moreover, this material containing -SO3 H groups is ideal to perform the second step to obtain octyl and decyl glucosides in yields higher than 73 % at 120 °C. In addition, the sulfonated carbon catalyst (C-SO3 H) can be reused with only a slightly decrease of its activity after four consecutive cycles.

The Cosmetic Ingredient Review Expert Panel (Panel) reviewed the safety of methyl glucose polyethers and esters which function in cosmetics as skin/hair-conditioning agents, surfactants, or viscosity increasing agents. The esters included in this assessment are mono-, di-, or tricarboxyester substituted methyl glucosides, and the polyethers are mixtures of various chain lengths. The Panel reviewed available animal and clinical data, including the molecular weights, log Kows, and other properties in making its determination of safety on these ingredients. Where there were data gaps, similarities between molecular structures, physicochemical and biological characteristics, and functions and concentrations in cosmetics allowed for extrapolation of the available toxicological data to assess the safety of the entire group. The Panel concluded that there likely would be no significant systemic exposure from cosmetic use of these ingredients, and that these ingredients are safe in cosmetic formulations in the present practices of use and concentration.