D(+)-Raffinose pentahydrate (D-Raffinose pentahydrate)

Dehydration of raffinose pentahydrate: structures of raffinose 5-, 4.433-, 4.289- and 4.127-hydrate at 93 K

Raffinose [or O-α-D-galactopyranosyl-(1→6)-α-D-glucopyranosyl-(1→2)-β-D-fructofuranoside] pentahydrate, C18H32O16·5H2O, (I), and three lower hydrates, namely the 4.433-, (II), 4.289-, (III), and 4.127-hydrated, (IV), forms, obtained in the course of the dehydration of (I), have been studied. The unit cells in the space group P2?2?2? are of similar dimensions for all the crystals. The conformation of the raffinose molecules remains almost the same across the four crystal structures. The raffinose molecules are linked into a three-dimensional hydrogen-bonded network involving all the -OH groups, the ring and glycosidic O atoms, and the water molecules. Six water sites were identified in the structures of (II), (III) and (IV), of which W1, W4 and W6 (W = water) are partially occupied with their populations coupled. W1, W4 and one of the -OH groups of the galactose ring form an infinite hydrogen-bonding chain around a 2? axis parallel to the a axis (denoted chain A), and W6 and the same -OH group form a similar chain (chain A') disordered with chain A. The occupancy ratio of chain A to chain A' for N-hydrates (N is a hydration number between 4 and 5) is (N - 4):(5 - N). The transformation of chain A to chain A' as part of the dehydration process has little effect on the rest of the structure. Thus, the dehydration proceeds without significant impact on the crystal structure.

The hydrogen bonding in the crystal structure of raffinose pentahydrate

The crystal structure of raffinose pentahydrate, O-alpha-D-galactopyranosyl-(1----6)-O-alpha-D-glucopyranosyl-(1----2)- beta-D- fructofuranose pentahydrate, C18H32O16.5H2O, has been redetermined using low-temperature, 119 K, CuK alpha X-ray data. All hydrogen atoms were unambiguously located on difference syntheses. The final R-factor is 0.036 for 2423 observed structure amplitudes. The hydrogen bonding is composed of infinite chains, which are linked through the water molecules to form a three-dimensional network containing a chain of five linked water molecules. Three of the infinite chains extend in the directions of the crystallographic axis of the space group P2(1)2(1)2(1). Four of the water molecules accept two hydrogen bonds and one accepts one. All the hydroxyls and the ring and glycosidic oxygen atoms are involved in the hydrogen bonding. With one exception, the ring and glycosidic oxygens are hydrogen-bonded by means of the minor components of unsymmetrical three-center bonds.

Hydration behaviour of some mono-, di-, and tri-saccharides in aqueous sodium gluconate solutions at (288.15, 298.15, 308.15 and 318.15)K: volumetric and rheological approach

Thermodynamic and transport properties are very useful in providing valuable information regarding the hydration characteristics of saccharides and play a pivotal role in the study of taste behaviour of saccharides in mixed aqueous solutions. The effects of sodium gluconate and other sodium salts on the hydration behaviour and the basic taste quality of saccharides have been studied from measured apparent molar volumes (V2,?), partial molar volumes (V2(°)) at infinite-dilution, and viscosity B-coefficients, of eight monosaccharides, six disaccharides and two trisaccharides in (0.25, 0.50, 1.00 and 1.50)molkg(-1) aqueous sodium gluconate solutions over a temperature range of (288.15-318.15)K and at atmospheric pressure. Partial molar volumes of transfer (ΔtV2(°)) and viscosity B-coefficients of transfer (ΔtB) of saccharides and other parameters such as isobaric expansion coefficients, interaction coefficients (using McMillan-Mayer theory), and dB/dT parameters have also been determined and discussed in terms of solute (saccharide)-cosolute (sodium gluconate) interactions.

Water diffusion in hydrated crystalline and amorphous sugars monitored using H/D exchange

Water interacts with pharmaceutical materials in a number of different ways. The aim of this study was to investigate if exchange experiments with D(2)O can provide useful insights into the structure of hydrated materials. Raffinose pentahydrate, trehalose dihydrate, and sucrose were used as model compounds in conjunction with their amorphous counterparts. Following exposure to D(2)O vapor, the exchange of water of hydration and/or hydroxyl groups was monitored using Raman spectroscopy. For the amorphous materials, all of the sugar hydroxyl groups were found to exchange on exposure to D(2)O, providing evidence that water has no fixed site in amorphous materials, nor is access to different parts of the molecule restricted. For raffinose pentahydrate and trehalose dihydrate, exchange of both hydrate water and hydroxyls was incomplete, suggesting that there are specific pathways for diffusion into and within the crystal structure. The results are rationalized based on the known crystal structures. Using exchange experiments to investigate hydrates thus appears to be a useful probe of structure.

Liver regeneration in rats administered high levels of carbohydrates

Partially hepatectomized male rats were administered high levels of carbohydrates by drinker, in a casein-cellulose synthetic medium and in a commercial meal over a period of 10 days after surgery and the amount of liver regenerating or the increment ascertained; representative hepatic glycogen changes were also followed. Of the carbohydrate solutions, 5% levulose, 5% levulose+5% glucose and 10% sucrose increased the extent of liver regeneration as was also the case with the synthetic diet suplemented with 30 and 60% glucose, 30 and 60% levulose, 30% levulose+30% glucose, 30% each of galactose and the arabinoglactan, Stractan and 60% each of sucrose, honey and unsulphured molasses. The liver increments and glycogen contents were in the control range for animals fed the synthetic diet containing 30% each of lactose, sorbitol, corn starch and raffinose pentahydrate, 5% ascorbic acid and 15% L-arabinose but the liver glycogen was depressed with 30% xylose, a diet which was poorly tolerated; 15% mannitol caused a decrease inthe increment. The incorporation of several sugars into the commercial rat meal, including xylose (11%), raffinose (15%), L-arabinose (8%), D-arabinose (5%), L-sorbose (17%), galactosamine (0.20%) and galactono-gamma-lactone (10%), led to little change over the control increments. In intact rats fed the synthetic diet containing 30% each of glucose, lactose, galactose, sucrose and levulose for an interval of 10 days, the wet and dry liver--body weight ratios were significantly elevated only with the last two sugars but liver glycogen was increased in each instance.