Effects of Counter-ion Form of a Cation-exchange Resin and Ethanol Content of Eluent on the Distribution Coefficients of Galactose, Tagatose, and Talose onto the Resin

Abstract

Optimum conditions for chromatographic separation, at 30℃, of galactose, tagatose, and talose were determined by investigation of the effects of the counter-ion form of cation-exchange resin and the ethanol content of eluent on the distribution coefficients of the monosaccharides onto the resin. Resin in the K + form with a divinylbenzene content of 8% was found to be most suitable for the separation. The distribution coefficients of all the solutes on the resin were increased as the ethanol content of eluent increased.Keywords: cation-exchange resin, distribution coefficient, tagatose IntroductionRare sugars are saccharides that occur in only small amounts in nature, and some of them have attracted attention due to their physiological functionality. Xylitol is one such rare sugar, which has an anticaries effect (Söderling et al., 1989) and is contained in gum as a sweetener. d-Psicose, which is an epimer of d-fructose at the C-3 position, is very low in calories and has a beneficial effect on insulin resistance (Matsuo et al., 2002; Hossain et al., 2012).d-Allose, which is an epimer of d-glucose at the C-3 position, has demonstrated preventative effects in ischemia reperfusion injury and hyperpiesia. However, rare sugars are generally very expensive. The high cost restricts investigation of their physiological and textural functionalities. Because of this, the development of effective mass production processes for rare sugars is desired to promote these investigations and achieve industrialization of the production process.Enzymatic methods for producing rare sugars (Takeshita et al., 2000; Granström et al., 2004; Morimoto et al., 2006) have been reported, in addition to a method using anion exchange (Takamine et al., 2009). We reported that isomerization of the common sugar d-galactose to d-tagatose and d-talose, which are rare sugars, was promoted in subcritical aqueous ethanol (Gao et al., 2015). An enzymatic method has also been developed for the production of d-tagatose (Kim et al., 2003). Isomerization in a subcritical fluid would be expected to be more effective than in conventional methods because of a higher reaction rate at higher temperature.d-Tagatose, which is a C-4 epimer of fructose, shows promise as replacement for sucrose and as a therapeutic agent against type 2 diabetes and obesity (Levin et al., 1995; Lu et al., 2008).Because isomerization of d-galactose produces a mixture of unreacted substrate and the products d-tagatose and d-talose, a separation process is required to obtain the desired product, d-tagatose. Ligand-exchange chromatography using cationexchange resin has been commonly used in saccharide separation due to the difference in complex formation or affinity between the counter-ion of the resin and the saccharides (Goulding, 1975; Caruel et al., 1991; Stefansson and Westerlund, 1996). Because water is used as an eluent, the chromatographic separation of saccharides is suitable for industrial purposes. The type of counterion and the divinylbenzene (DVB) content of the resin...

Trends in lactose-derived bioactives: synthesis and purification

“…However, the authors reported the need of an additional chromatographic step to remove the boric acid. More recently, Tamura et al [131] evaluated a number of cation-exchange resins for the separation of galactose, tagatose and talose, obtaining the best result with Na + and K + as counterions and cross-linking of 6%. In addition, the purification of lactobionic acid has been studied using cation-exchange resins [132].…”