Structural characterization and antioxidant activity of pectic polysaccharides from Veronica peregrina L.

BACKGROUND: Pectins are a class of acidic polysaccharides with complex structures. Different pectin molecules are composed of different domains, which have an important impact on their biological activity. OBJECTIVE: This study aimed to determine the structural features and the antioxidant activities of the pectic polysaccharides isolated from Veronica peregrina L. METHODS: The polysaccharide was isolated from Veronica peregrina L by water extraction and fractionated by ion exchange chromatography and gel permeation chromatography. The structure features of the pectic polysaccharides were determined by Fourier transforminfrared spectroscopy (FT-IR) and Nuclear magnetic resonance (NMR). The antioxidant activities was evaluated by the DPPH, OH and ABTS radical scavenging ability. RESULTS: WVPP-A2b and WVPP-A3b, with molecular weights of 48.7 × 10(4) and 77.6 × 10(4) kDa, respectively, contained homogalacturonan (HG), rhamnogalacturonan I (RG-I), and rhamnogalacturonan II (RG-II) domains with a mass ratio of 2.08:2.64:1.00 and 3.87:4.65:1:00, respectively. The RG-I domain contained an arabinogalactan II backbone and arabinans consisting of t-Araf, (1→5)-α-Araf, and (1→3,5)-α-Araf. WVPP-A3b also contained short chains consisting of the [t-Araf-(1→5)-α-Araf-(1→] structural unit. WVPP-A3b showed stronger ability to scavenge DPPH, hydroxyl, and ABTS radicals, which was potentially associated with its high content of galacturonic acid and presence of the HG domain. CONCLUSION: The results provide information for enhancing knowledge of the structureactivity relationship of pectic polysaccharides from V. peregrina and their potential application in the healthcare food field.