Polymeric Compounds of Lingonberry Waste: Characterization of Antioxidant and Hypolipidemic Polysaccharides and Polyphenol-Polysaccharide Conjugates from Vaccinium vitis-idaea Press Cake

Abstract

Lingonberry (Vaccinium vitis-idaea L.) fruits are important Ericaceous berries to include in a healthy diet of the Northern Hemisphere as a source of bioactive phenolics. The waste generated by the V. vitis-idaea processing industry is hard-skinned press cake that can be a potential source of dietary fiber and has not been studied thus far. In this study, water-soluble polysaccharides of V. vitis-idaea press cake were isolated, separated, and purified by ion-exchange and size-exclusion chromatography. The results of elemental composition, monosaccharide analysis, ultraviolet-visible and Fourier-transform infrared spectroscopy, molecular weight determination, linkage analysis, and alkaline destruction allowed us to characterize two polyphenol-polysaccharide conjugates (PPC) as neutral arabinogalactans cross-linked with monomeric and dimeric hydroxycinnamate residues with molecular weights of 108 and 157 kDa and two non-esterified galacturonans with molecular weights of 258 and 318 kDa. A combination of in vitro and in vivo assays confirmed that expressed antioxidant activity of PPC was due to phenolic-scavenged free radicals, nitrogen oxide, hydrogen peroxide, and chelate ferrous ions. Additionally, marked hypolipidemic potential of both PPC and acidic polymers bind bile acids, cholesterol, and fat, inhibit pancreatic lipase in the in vitro study, reduce body weight, serum level of cholesterol, triglycerides, low/high-density lipoprotein-cholesterol, and malondialdehyde, and increase the enzymatic activity of superoxide dismutase, glutathione peroxidase, and catalase in the livers of hamsters with a 1% cholesterol diet. Polysaccharides and PPC of V. vitis-idaea fruit press cake can be regarded as new antioxidants and hypolipidemic agents that can be potentially used to cure hyperlipidemic metabolic disorders.

Keywords: Vaccinium vitis-idaea; antioxidant activity; arabinogalactan; galacturonan; hypolipidemic activity; lingonberry; polyphenol–polysaccharide conjugates; polysaccharides.

Figure 1

Flow chart for the extraction and fractionation of polysaccharides from Vaccinium vitis-idaea press cake. Abbreviation used: VVPS, V. vitis-idaea total polysaccharide fraction; DEAE, diethylaminoethyl cellulose; DEAE–sepharose fast-flow gel, diethylaminoethyl cellulose sepharose fast-flow gel.

Figure 2

Van Krevelen diagram (correlation between O/C ratio and H/C ratio) for VVPS, DEAE–cellulose fractions (labeled as eluent type), hexose (Hex), pentose (Pent), desoxyhexose (dHex), and hexuronic acid (HexA) (a) and its enlarged fragment (b). Abbreviation used: VVPS, V. vitis-idaea total polysaccharide fraction; DEAE, diethylaminoethyl cellulose.

Figure 3

Elution curve of DEAE-1% NaOH fraction on the DEAE–sepharose fast-flow gel.

Figure 4

Characteristics of DEAE–sepharose fast-flow gel fractions of DEAE-1% NaOH-f1 (f1), DEAE-1% NaOH-f2 (f2), DEAE-1% NaOH-f3 (f3), and DEAE-1% NaOH-f4 (f4): (a) elution profiles on GP-HPLC; (b) UV–Vis spectra of 1 mg/mL water solutions; (c) FTIR spectra.

Figure 5

HPLC chromatogram of alkaline destruction products of DEAE–1% NaOH-f1 (f1) and DEAE–1% NaOH-f2 (f2) polymers (a) degradation products labeled 1–7 as described in Table 7 and ESI–MS/MS spectra (positive ionization) of degradation products 3 (b), 4 (c), 5 (d), 6 (e), and 7 (f).

Figure 5

HPLC chromatogram of alkaline destruction products of DEAE–1% NaOH-f1 (f1) and DEAE–1% NaOH-f2 (f2) polymers (a) degradation products labeled 1–7 as described in Table 7 and ESI–MS/MS spectra (positive ionization) of degradation products 3 (b), 4 (c), 5 (d), 6 (e), and 7 (f).

Figure 6

Changes in body weight (a), serum total cholesterol (b), serum total triglycerides (c), serum low-density lipoprotein–cholesterol (LDL–C) (d), serum high-density lipoprotein–cholesterol (HDL–C) (e), serum malondialdehyde level (MDA) (f), liver superoxide dismutase (SOD) (g), liver glutathione peroxidase (GPX) (h) and liver catalase (i) in hamsters with a normal diet (N), with a 1% cholesterol diet (C), with a 1% cholesterol diet + simvastatin (10 mg/kg/day; S), with a 1% cholesterol diet + DEAE–1% NaOH-f2 polysaccharide (250 mg/kg/day; F2), with a 1% cholesterol diet + DEAE–1% NaOH-f3 polysaccharide (250 mg/kg/day; F3) before the feeding period (-0) and after a 6-month feeding period (-6). i—p < 0.05 vs. 1% cholesterol diet group (C-group); ii—p < 0.05 vs. 1% cholesterol diet + simvastatin group (S-group).