Extraction, preparation, and carboxymethyl of polysaccharide from Lotus root

Abstract

In this study, we extracted lotus root polysaccharide (LRP) and synthesized carboxymethylated lotus root polysaccharide (CM-LRP) using response surface methodology (RSM). The monosaccharide component of LRP was analyzed by pre-column derivatization high performance liquid chromatography (PCD-HPLC). The polysaccharide was characterized by ultraviolet (UV) spectroscopy scan, Fourier transform infrared spectroscopy (FTIR), circular dichroism spectrometer (CD), and scanning electron microscopy (SEM). It was found that the main monosaccharide component of LRP was glucose, accounting for more than 98% of the total polysaccharide component. RSM analyses revealed that the optimal conditions for CM-LRP synthesis were a reaction duration of 2.22 h, the chloroacetic acid dosage is 2.02 g, and a temperature of 46.87 °C. Under these conditions, the predicted degree of substitution (DS) was determined to be 0.5101. The superoxide anion, ferrous ion and hydroxyl radical antioxidant system were constructed to study the antioxidant activity of LRP and CMLRP. The activity of CMLRP to remove ferrous ions and hydroxyl radicals were significantly stronger than that of LRP, and it also showed a certain concentration-dependent. LRP has a better scavenging ability than CMLRP in scavenging superoxide anion free radicals. Our data revealed that CM-LRP is a promising natural antioxidant with potential value as a food supplement.