Abstract
Three novel low molecular weight polysaccharides (RLP-1a, RLP-2a, and RLP-3a) with 9004, 8761, and 7571 Da were first obtained by purifying the crude polysaccharides from the fruits of a traditional Chinese medicinal herb Rosae Laevigatae. The conditions for polysaccharides from the R. Laevigatae fruit (RLP) extraction were optimized by the response surface methodology, and the optimal conditions were as follows: extraction temperature, 93°C; extraction time, 2.8 h; water to raw material ratio, 22; extraction frequency, 3. Structural characterization showed that RLP-1a consisted of rhamnose, arabinose, xylose, glucose, and galactose with the ratio of 3.14 : 8.21 : 1 : 1.37 : 4.90, whereas RLP-2a was composed of rhamnose, mannose, glucose, and galactose with the ratio of 1.70 : 1 : 93.59 : 2.73, and RLP-3a was composed of rhamnose, arabinose, xylose, mannose, glucose, and galactose with the ratio of 6.04 : 26.51 : 2.05 : 1 : 3.17 : 31.77. The NMR analyses revealed that RLP-1a, RLP-2a, and RLP-3a contained 6, 4, and 6 types of glycosidic linkages, respectively. RLP-1a and RLP-3a exhibited distinct antioxidant abilities on the superoxide anions, 1,1-diphenyl-2-picrylhydrazyl (DPPH), and hydroxyl radicals in vitro. RLPs could decrease the serum lipid levels, elevate the serum high-density lipoprotein cholesterol levels, enhance the antioxidant enzymes levels, and upregulate of FADS2, ACOX3, and SCD-1 which involved in the lipid metabolic processes and oxidative stress in the high-fat diet-induced rats. These results suggested that RLPs ameliorated the high-fat diet- (HFD-) induced lipid metabolism disturbance in the rat liver through the peroxisome proliferator-activated receptor (PPAR) signaling pathway. Low molecular weight polysaccharides of RLP could be served as a novel potential functional food for improving hyperlipidemia and liver oxidative stress responses.
Highlights
Rosae Laevigatae is a perennial shrub belonging to the Rosaceae family, and its fruits have been used widely as edible food and medicinal herb in the tropical and subtropical areas of Asia for thousands of years
The homogeneity and molecular weight of the purified RLPs were determined by high performance gel permeation chromatography (HPGPC), which was performed on a HPLC-1525 liquid chromatography instrument (Waters, Massachusetts, USA) with a TSK-GEL G5000 PWXL column (7:8 × 300 mm) series connected with a TSK-GEL G3000 PWXL column (7:8 × 300 mm) (Tosoh, Tokyo, Japan)
Compared with the high-fat diet group (HFD) group, the high-dose RLP group (HRLP) group reduced TG (P < 0:05), total cholesterol (TC) (P < 0:05), free fatty acid (FFA) (P < 0:05), and LDL-C (P < 0:1) levels by 16.3%, 47.0%, 27.8%, and 14.8%, respectively, and the HDL-C levels significantly increased by 35.0% (P < 0:05), indicating that RLP with higher dosage intervention had stronger hypolipidemic activities in rats, and the hypolipidemic activity of low-dose RLP group (LRLP) was weaker than that of HRLP
Summary
Rosae Laevigatae is a perennial shrub belonging to the Rosaceae family, and its fruits have been used widely as edible food and medicinal herb in the tropical and subtropical areas of Asia for thousands of years. Plant polysaccharides have been attracting great attention due to their natural and nontoxic properties with no side effects Their bioactivities and pharmacological functions were identified in terms of antioxidation [9], anticancer [10], antiinflammatory [11], antimicrobial [12], hepatoprotective [13], hypolipidemic, and hypoglycemic activities [14, 15], BioMed Research International indicating a wide application prospect in medicine. Polysaccharides with larger molecular weight appeared high apparent viscosity, poor water solubility, and complex structures and conformations [20] They are difficult to enter into cells or attach to the receptors to exert their biological effects [21]. The study could provide implications for the utilization of low molecular weight RLPs in functional food to improve blood lipid metabolism
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