P-Dextrin

Attempts to stabilize anthocyanins by complex inclusion with a- and P-cyclo-dextrins failed on the contrary, a discoloration of anthocyanin solutions was observed.Thermodynamic and kinetic investigations demonstrated that inclusion and copigmentation had opposite effects. In the anthocyanins, the cw-chalcone colorless structure is the best species adapted to inclusion into the P-dextrin cavity, shifting the equilibrium toward colorless forms. "... 

Cellulase Hydrolysis of 3-l,4-glucan bonds in such polysaccharides as cellulose, yielding p-dextrins. 

We are grateful to Dr. John H. Cardellina, II, National Cancer Institute, Prof. D. John Faulkner, University of California, San Diego, and Prof. Raymond J. Andersen, University of British Columbia, for kindly providing us with H, C NMR spectra of natural clavepictines A, B, Pictamine, and lepadin B. We are also indebted to Dr. Thomas F. Spande, National Institute of Health, for measurement of the GC analysis of synthetic, racemic, and natural quinolizidine 2071 with P-dextrin chiral column, and to Prof. Andre Rassat, Ecole Normale Superieure, for kindly providing us with racemic quinolizidine 2071. 

The first reference to cyclodextrins was published in 1891 by the French scientist A. Villiers. He described the isolation of 3 g of crystalline substance from bacterial digest of 1000 g of starch [7]. He named the substance cellulosine , assuming that this substance is some sort of cellulose. Soon after, the Austrian microbiologist F. Schardinger isolated two crystalline compounds from bacterial digest of potato starch. He named these compounds crystalline dextrins and later changed the names to a-dextrin and P-dextrin [8], In 1935, Freudenberg and Jacobi discovered y-cyclodextrin [9]. 

The membrane used by Beck and Schultz (1972) had an average pore diameter of 88.8 A, a tortuosity of 1.1, and a porosity of 2.33%. The molecular diameter of P-dextrin is 17.96 A, and its diffusivity in dilute aqueous solution at 298 K is 3.22 x 10-6 cm2/s. Estimate the effective diffusivity of P-dextrin through this membrane at... 

Freudenberg and co-workers correctly proposed a cyclic structure for the CDs. However, the numbers of D-glucosyl moieties which they assigned to the a- and p-dextrin rings (five and six, respectively) were incorrect. The correct values of six and seven were determined... 

Synonyms Betadex Cycloheptaamylose Cycloheptaglucosan Cyclomaltoheptaose Schardinger p-dextrin... 

Scepter . See Ammonium imazaquin Schardinger o-dextrin. See Cyclodextrin Schardinger p-dextrin. See p-Cyclodextrin Schercamox C-AA. See Cocamidopropylamine oxide... 

Amylase occurs in many plants, such as barley, wheat, rye, soy beans, and potatoes, where it is generally accompanied by some a-amylase. [ -Amylase initiates hydrolysis at the nonreducing end of an amylose or amylopectin chain, and removes maltose units successively until the reducing end of the molecule is encountered in amylose or a branch is met in amylopectin. ( -Amylase is used commercially in the preparation of maltose symps. After P-amylase hydrolysis of amylopectin there remains a P-amylase limit dextrin. ( -Amylase has been used as a probe of the fine stmcture of amylopectin (43-46). 

Upon formulating these relationships, phenols with branched alkyl substituents were not included in the data of a-cyclodextrin systems, though they were included in (3-cyclodextrin systems. In all the above equations, the n term was statistically significant at the 99.5 % level of confidence, indicating that the hydrophobic interaction plays a decisive role in the complexation of cyclodextrin with phenols. The Ibrnch term was statistically significant at the 99.5% level of confidence for (3-cyclo-dextrin complexes with m- and p-substituted phenols. The stability of the complexes increases with an increasing number of branches in substituents. This was ascribed to the attractive van der Waals interaction due to the close fitness of the branched substituents to the (3-cyclodextrin cavity. The steric effect of substituents was also observed for a-cyclodextrin complexes with p-substituted phenols (Eq. 22). In this case, the B parameter was used in place of Ibmch, since no phenol with a branched... 

An expl prepd by mixing Ba nitrate, diarcoal and Amm picrate or amorph P 1888 An expl consisting of 3p Ba nitrate and lp AN, together with a small quant of dextrin or gum as binder... 

When the consumption of iodine is the same in two successive tests and a sample of the mixture is no longer coloured by iodine the saccharification is complete. Usually 75-80 per cent of the starch taken is converted into sugar. The rest of the starch is only broken down into dextrins, which are, however, also saccharified in the course of the subsequent fermentation. The volume of the mash is measured in a cylinder, and from the result of the final maltose titration the sugar content is calculated. For the C02-determination 10 c.c. are retained (cf. p. 402). 

A different approach to the resolution of sulfoxides was recently reported by MikcJajczyk and Drabowicz (35). It takes advantage of the fact that sulfoxides as well as other sulfinyl compounds ry easily form inclusion complexes with 3-cyclodextrin. Since -cycl dextrin (the host) is chiral, its inclusion complexes with racemic guest substances are mixtures of diastereomeis that can be formed in unequal amounts. In this way a series of alkyl phenyl, alkyl p-tolyl, and alkyl benzyl sulfoxides has been resolved. However, the optical... 

At around the same time, Breslow and co-workers described bifunctional cyclo-dextrin-based catalysts that were capable of hydrolysis of a bound phosphate ester [88]. In later studies, an AD isomer (Scheme 4.9) of a P-cyclodextrin bisimidazole catalyst turned out to be the fastest catalyst for enolization of p-tert-butylacetophe-none (Scheme 4.9) [89]. Here, the extra binding is provided by the P-cyclodextrin... 

Neben optisch aktiven Basen bzw. Anunonium-Ionen vermogen nach Cramer und Dietsche (75, 76) auch EinschluBkatalysatoren die Cyan-hydrin-Bildung asymmetrisch zu lenken. In Gegenwart von a-Cyclo-dextrin wurden aus o- und p-Chlorbenzaldehyd und HCN schwach rechtsdrehende Cyanhydrine erhalten. 

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