Optimization of extraction process from Taraxacum officinale polysaccharide and its purification, structural characterization, antioxidant and anti-tumor activity

Abstract

In order to get high yield polysaccharide from Taraxacum officinale, single factor experiment and an orthogonal experiment were applied to optimize the best extraction conditions. In this experiment, a novel comparison was made to explore and compare the effect of enzyme assisted and ultrasonic assisted hot water extraction of polysaccharide from T. officinale. The optimum conditions were as follows: raw material to water: 1:15, extraction temperature: 65 °C, extraction time: 2 h and ultrasound assisted, and the experimental extraction yield was 6.46% ± 0.19% (n = 3). A novel neutral polysaccharide (TOP, about 1.7 × 103 Da) was isolated from the T. officinale, which contents of total sugar, uronic acid and protein were 90.16%, 0.17% and 0.26%, respectively. Monosaccharide analysis, Methylation analysis and NMR analysis revealed that TOP had a backbone composed of (1 → 4)-β-D-Glcp with branching at O-2 of (1 → 2,4)-β-D-Glcp and four main branches of (1 → )-β-D-Glcp (1 → 3)-α-D-Galp (1 → 3)-α-D-Manp and (1 → )-α-L-Araf units. Additionally, the antioxidant activity suggested that TOP had great antioxidant effect, especially scavenging activity for DPPH radical and reducing power. TOP polysaccharide has anti-tumor activity, which can inhibit the proliferation of HepG2 cells. This study has shown that TOP can be explored as a novel natural antioxidant and anti-tumor drug.