ABSTRACT
Agaro- and carra-oligosaccharides were produced by partial acid hydrolysis of commercial agarose and kappa-carrageenan. Di- and tetrasaccharides were purified by gel filtration chromatography and characterized by NMR (1D and 2D) spectroscopy and ESIMS. The following oligosaccharides were obtained: agarobiose, agarotetraose, kappa-carrabiose and kappa-carratetraose. Agarobiose and agarotetraose were used as standards to develop a high performance size exclusion chromatography (HPSEC) method which was utilized to study the hydrolysis rate of agarose and oligosaccharide production. Six hours of hydrolysis (0.1 M TFA, 65 ºC) produced mainly di- and tetrasaccharides. The methodology for oligosaccharide production and evaluation developed in the present work shows good potential for the production of bioactive oligosaccharides.
ABSTRACT
Objective Since the discovery of multiple bioactivities of agarobiose oligomers, the establishment of quantitative analysis of agarobiose oligomers obtained under different hydrolysis modes would be of much importance. Methods Agarobiose oligomers ranged from biose, tetraose, hexaose, octaose, to decaose were isolated and purified by gel chromatography on Sephadex column. The agarobiose oligomers were separated in RP-HPLC after introducing ?-naphthylamine into compounds. Results Each oligomer could be quantified with good linearity and the lowest detection limit reached 0.1～2 ?g?mL -1. The chromatograms profiles under different hydrolysis modes(HCl, citric acid, solid acid, and hydroxyl radical degradation)showed that the content of agarobiose could reach more than 57.8 % using solid acid hydrolysis with best yield of 33.2 % . While HCl could degrade agar into a series of agaro-oligosaccharides from biose to decaose. The yield of oligosaccharides was low if hydrated by citric acid. The method of Fenton degradation could increase the speed of hydrolysis, but the products were more complex. Conclusion The method established here could be useful for analysis of hydrolysates of oligomers under different hydrolysis modes.
ABSTRACT
Objective Agaro-oligosaccharides have been proved to possess the antioxidative ability in vitro. This work focus on the preparation of agaro-oligosaccharides and their antioxidant effect in vivo. Method Agaro-oligosaccharides were hydrolytically obtained and the activated carbon column was used to purify the oligosaccharides. The antioxidative effects of the 10 % ethanol eluted fraction on tissue peroxidative damage induced by carbon tetrachloride (CCl 4) was also investigated in rat. Result Agarobiose of high purity was consequently eluted from chromatography in the fractions of 5 % and 8 % ethanol, agarotetraose and agarohexaose in 10 % to 15 % ethanol, as well as high degree of polymerization (DP) oligosaccharides in 25 % ethanol. The antioxidative results indicated that agaro-oligosaccharides could elevate the activities of SOD, GSH-Px and decrease the level of MDA, GPT, GOT significantly. At a dose of 400 mg?kg~ -1, MDA level was reduced 44 % and 21 % in liver and heart, the activities of SOD and GSH-Px would amount to the peak value in liver and serum, while GPT level was decreased 22 % in serum. Conclusion The purity of agaro-oligosaccharides with different range of DPs was improved by activated carbon column, which possesses the property of different absorbance ability towards oligosaccharides with various DPs and high isolating capability. The animal test also indicated that agaro-oligosaccharides could inhibit the oxidative damage in vivo.
ABSTRACT
Objective:To evaluate the effect of agar-oliogsaccharides (mainly containing agarobiose) on blood glucose level and oxidation-antioxidation status in alloxan-induced diabetic mice. Method: The inhibitory activity of agarobiose on ?-glucosidase was investigated. Alloxan was used to establish non-obese diabetic (NOD) mice model. After 14 d administration of agarobiose, blood glucose, MDA, SOD, GSH and GSH-Px levels were determined. Results:Agarobiose showed inhibitory activity on ?-glucosidase with IC50=1.39 mg/ml, Ki=0.52 mg/ml. In a certain concentration (200-400 mg/kg bw), agaro-oligosaccha- rides reduced the blood glucose level remarkably, and the oxidative indices were also improved in heart, liver, lung and brain. The blood glucose level (P