Glucosides structures

For polyurethane production, Donnelly [109] has carried out the synthesis of copolyurethanes based on mixtures of commercial poly(THF diol)s with glucose. Complex products resulted, which can be represented by mono- or bis(glucoside) structures. From a variety of polyol blends, solid polyurethanes were prepared which ranged from linear, soluble, weak elastomers to polymers of higher transition temperature and stiffness, low solubility, and low extension under tensile load [110]. 

C-aryl glucosides, structure, 86/ 94/ C-aryl mannosides, structure, 85/ synthesis... 

As an example, the steric structure of cellulose is given below (one sheet of white paper held perpendicular to the page is needed to separate the two fields of vision to see the structure). The primary (1 ->4)-p-glucosidic structure, the secondary arrangement, as well as the extended ribbon tertiary structure can be seen. 

In the olive, there are two main compounds, besides that reported in the literature. The first one is oleuropein, the first secoiridoid isolated in 1960 by Panizzi in Roma, as mentioned above. The second one is the comoside that is a hemiquinone glucoside, structurally and biogenetically related to hydroxy-tyrosol that is the principal free phenol in the olive. It should be remembered that, depending on the olive cultivar, the oleuropein can be prevalent against the comoside, or it could be the contrary, until reaching the equality. 

The existence of two forms of glucose and of two isomeric methyl glucosides, as well as other experimental evidence, have led to the adoption of the ring structures (I) and (II) ... 

The configuration of the glucoside linkage is different in the two, however. Structures [I] and [II], respectively, illustrate that the linkage is a /3-acetal-hydrolyzable to an equitorial hydroxide—in cellulose, and an a-acetal-hydrolyz-able to an axial hydroxide—in amylose, a starch ... 

From the plant Escallonia pulvemlenta (Escalloniaceae), which grows in Chile, an iridoid gluco-side of elemental composition CigZ/j On was isolated. Formula / gives the structure of the iridoid glucoside skeleton... 

Research into the copigmentation of anthocyanins started as early as 1913 when Willstatter and Everest determined the chemical structure of cyanidin 3-glucoside isolated from blue cornflowers and red roses, and attributed the color changes to different pH levels in cell saps. This theory, however, was questioned and in 1916, Willstatter and Zollinger,revising the previous work, proposed a new theory according to which the colors of the anthocyanins varied significantly by the effects... 

Duenas, M., et al., UV-visible spectroscopic investigation of the 8,8-methylmethine catechin-malvidin-3-glucoside pigments in aqueous solutions structural transformations and molecular complexations with chlorogenic acid, J. Agric. Food. Chem., 54, 189, 2006. 

Quantitation of anthocyanins has become simple and fast since many anthocy-anin standards became commercially available as external standards in the past decade. When the standards are not available, individual anthocyanins or total monomeric anthocyanins can be determined by the use of a generic external standard such as commercial cyanidin-3-glucoside or other compound structurally similar to the analytes of interest. Individual and total peak areas are measured at 520 nm or their and quantified using external standards by which values are typically slightly different from those via the pH differential method. ... 

Another problem is that the anthocyanin mixtures may be very complicated and not all absorptivity coefficients may be known. Even when they are known, it is necessary to first evaluate whether the objective is the estimation of total anthocyanin content or the determination of individual pigments, and then to decide which absorption coefficient(s) to use. The absorptivity is dependent on both the chemical structure of the pigment and also on the solvent used, and preferably the coefficient used should be one obtained in the same solvent system as the one used in the experiment. If the identity of the pigment is unknown, it has been suggested that it could be expressed as cyanidin-3-glucoside since that is the most abundant anthocyanin in nature. 

Many recent stndies of NMR spectroscopy have been reported for structure elucidation of anthocyanins from many plant materials such as carrot, tart berries, boysenberries, " flowers, black soybeans, and anthocyanin and flavonol derivatives in red wine. Ginsti et al. (1998) structurally elucidated two novel diacylated anthocyanins and two monoacylated anthocyanins from radish Raphanus sativus) by one- and two-dimensional NMR. Anderson et al. (2006) applied two-dimensional NMR to characterize carboxypyranoanthocyanins. Two 3-deoxyantho-cyanins, lnteolinidin-5-glncoside, and apigeninidin-5-glucoside were identified by Swinny et al. nsing H and C NMR. 

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