ABSTRACT
A method using partial least squares (PLS) for simultaneous determination of neutral and uronic sugars was developed in this paper. This method is based on the development of the reaction between the analytes and anthrone. The calibration set was built with 25 binary solutions at the concentrations ranging from 20 to 100µg/mL for glucose and from 10 to 50µg/mL for glucuronic acid. An independent prediction set was utilized to check the robustness of the PLS calibration model. The root-mean-square error of prediction (RMSEP) values for neutral and uronic sugars are 1.2233 and 1.9367, respectively. The correlation coefficient for the prediction set (Rp(2)) values for them are 0.9971 and 0.9767, respectively. Compared with the univariate method, the proposed method improves detection accuracy. In addition, it was also applied to commercial polysaccharides and Glycyrrhiza uralensis polysaccharides (GUPs), and the results indicated that the PLS model was suitable for simultaneous determination of neutral and uronic sugars.
Subject(s)
Carbohydrates/analysis , Carbohydrates/chemistry , Spectrophotometry, Ultraviolet/methods , Uronic Acids/chemistry , Calibration , Glycyrrhiza/chemistry , Least-Squares Analysis , Principal Component Analysis , Reproducibility of Results , Time FactorsABSTRACT
Glycyrrhiza uralensis, an important Chinese medicine, has a long history of use in China. In this study, three water-soluble polysaccharides fractions (GUPs-1, GUPs-2 and GUPs-3) were isolated and purified from the root of G. uralensis by DEAE-52 and Sephadex G-100 column chromatography. Physicochemical properties and antioxidant activities of the three purified polysaccharides were investigated. The molecular weights of GUPs-1, GUPs-2 and GUPs-3 were 10,160, 11,680 and 13,360 Da, and the ratios of glucose were 23.4%, 14% and 1.13%, respectively. The antioxidant activities of the three purified polysaccharides followed the order: GUPs-1>GUPs-2>GUPs-3. GUPs with lower molecular weight and higher ratio of glucose, basically exhibited higher antioxidant activities at the same concentration. This indicated that the molecular weight and the ratio of monosaccharide composition of the GUPs could affect the antioxidant activities.
Subject(s)
Antioxidants/chemistry , Glycyrrhiza uralensis/chemistry , Iron Chelating Agents/chemistry , Plant Roots/chemistry , Polysaccharides/chemistry , Antioxidants/isolation & purification , Biphenyl Compounds/antagonists & inhibitors , Chromatography, Gel , Chromatography, Ion Exchange , Glucose/analysis , Hydroxyl Radical/antagonists & inhibitors , Iron Chelating Agents/isolation & purification , Molecular Weight , Oxidation-Reduction , Picrates/antagonists & inhibitors , Polysaccharides/isolation & purificationABSTRACT
A method for quantitative analysis of the polysaccharides contents in Glycyrrhiza was developed based on near infrared (NIR) spectroscopy, and by adopting the phenol-sulphuric acid method as the reference method. This is the first time to use this method for predicting polysaccharides contents in Glycyrrhiza. To improve the predictive ability (or robustness) of the model, the competitive adaptive reweighted sampling (CARS) mathematical strategy was used for selecting relevance wavelengths. By using the restricted relevance wavelengths, the PLS model was more efficient and parsimonious. The coefficient of determination of prediction (Rp(2)) and the root mean square error of prediction (RMSEP) of the obtained optimum models were 0.9119 and 0.4350 for polysaccharides. The selected relevance wavelengths were also interpreted. It proved that all the wavelengths selected by CARS were related to functional groups of polysaccharide. The overall results show that NIR spectroscopy combined with chemometrics can be efficiently utilised for analysis of polysaccharides contents in Glycyrrhiza.
