Isolation, Identification And Biological Function Of Oligosaccharides From Coix Lachryma-jobi

Coix chryma-jobi kernel(Coix lachryma-jobi[L] var.frumentacea Makino), is a special economical resource in Fujian. In this thesis, the extraction and preliminary purification conditions were investigated. The anti-oxidative effect of Coix seed oligosaccharides and the proliferation effect of Coix seed oligosaccharides on bifidobacterium in vitro have been studied. Purified Coix seed oligosaccharides (P-CSO) was isolated and fractionated by preparative chromatography. The monosaccharide composition and the structure of P-CSO were analyzed.The result of water extracting Coix seed oligosaccharides (CSO) showed that the extraction rate of CSO were affected by liquid-solid ratio, extracting time and extracting temperature. The technological conditions for CSO extraction were determined through orthogonal experiments:liquid-solid ratio was 20:1, extracting time was 3 h, and extracting temperature was 75℃. Under the optimal condition the extraction rate would be increased to 0.59%. The result of ultrasonic-assisted extracting Coix seed oligosaccharides (UCSO) showed that the ultrasonic power, ultrasonic time and liquid-solid ratio could influence the extraction rate of UCSO. The optimal conditions of UCSO were optimized with response surface methods. When the liquid-solid ratio was 20:1, ultrasonic time was 27 min and ultrasonic power was 450 W, the extraction rate reached to 0.94%.The CSO purification process was investigated, and the obtained results demonstrated that the optimal conditions of enzymatic hydrolysis for deproteinization were as follows:the enzymolysis concentration was 1500 U, the enzymolysis time was 70 min, the enzymolysis temperature was 60℃ and pH value was 3.5. Under this conditions, the protein removing rate and the loss rate of oligosaccharides were determined as 65.47% and 9.05%, respectively. D101 macroreticular resin was applied for the decolorization of Coix seed oligosaccharides. The best conditions of decolorization were obtained with 0.3 g/mL of resin and 6 h of decoloring time.The anti-oxidative activity of CSO and P-CSO were studied in vitro. The results demonstrate that CSO and P-CSO have the capacity of scavenging-OH, O2-; DPPH-and T-AOC, but the anti-oxidative effect is not comparable to VC.The proliferation effect of P-CSO on bifidobacterium was studied. Instead of glucose (GLU), P-CSO and isomaltose oligosaccharide (IMO) were added into the basic culture medium of bifidobacterium. The results showed that P-CSO had the proliferation effect on bifidobacterium, and proliferation effect from P-CSO was superior to that from IMO and GLU. When the concentration of P-CSO in medium was 16g/L, the retardate time of bifidobacterium adolescence in P-CSO medium was 4 hrs shorter than that in IMO and GLU medium, with the significant promoting effect on the acid production of bifidobacterium.P-CSO was isolated and fractionated by preparative chromatography. Monosaccharide composition analyses of P-CSO were elucidated by high performance liquid chromatography. Infrared spectrum (IR), mass spectrum (MS) and nuclear magnetic resonance (NMR) were used for structural analyses of different P-CSO-fractions. The results showed that P-CSO2-1, P-CSO3-1, P-CSO4-1 were three major configurations of P-CSO, with the DP of 2,3,4 and the molecular weight of 666.22,504.17,342.12, respectively; Disaccharides were the main components of P-CSO; P-CSO was a neutral oligosaccharide and was identified as pyranose configuration, with of α-indican bond and β-indican bond.