ABSTRACT
BACKGROUND: Recent studies have shown that polysaccharides from Anoectochilus roxburghii (Wall.) Lindl. (ARPs) can reduce blood glucose levels, ameliorate oxidative stress and inflammation. However, whether ARPs have a beneficial effect on diet-induced obesity remain to be determined. PURPOSE: This study aims to investigate the effect and mechanism of ARPs in improving obesity and metabolic disorders induced by high-fat diet (HFD). METHODS: In this study, 6-week-old male mice were fed with HFD or chow diet for 13 weeks, and a dietary supplementation with ARPs was carried out. Glucose tolerance test and insulin tolerance test were performed to measure the glucose tolerance and insulin sensitivity. Adipose tissue and liver were isolated for analysis by qRT-PCR, Western blotting, hematoxylin-eosin staining and immunostaining. RESULTS: At week 13, body weight and fat mass were significantly increased by HFD, but ARPs supplementation abolished these phenotypes. Compared with HFD group, thermogenic genes including Ucp-1, Pgc-1α, Prdm16 and Dio2 in adipose tissue were up-regulated in ARPs-treated mice. In addition, ARPs decreased liver lipid accumulation by reducing lipid synthesis and increasing oxidation. Meanwhile, dyslipidemia and insulin resistance induced by HFD were improved by ARPs. Mechanistically, ARPs can promote fat thermogenesis via AMPK/SIRT1/PGC-1α signaling pathway. CONCLUSION: Dietary supplementation of ARPs can protect mice against diet-induced obesity, fatty liver and insulin resistance. Our study reveals a potential therapeutic effect for ARPs in regulating energy homeostasis.
ABSTRACT
Anoectochilus roxburghii is a traditional herb in China that can be potentially used to treat diabetes. A novel polysaccharide ARLP-W was isolated from Anoectochilus roxburghii by chromatography on DEAE-52 cellulose. Chemical analysis indicated that ARLP-W (8.1 × 104 Da) was mainly composed of mannose and glucose. The main linkages of glycosidic bonds of ARLP-W were ß-1, 4-Manp and α-1, 4-Glcp. The terminal Glcp was connected to Manp-via O-3. RT-qPCR and western blotting analysis showed that ARLP-W caused a significant reduction in the levels of the key gluconeogenesis enzymes phosphoenolpyruvate carboxykinase (PEPCK) and glucose 6-phosphatase (G6Pase) in the liver. The results of the insulin resistance tests indicated that ARLP-W increased glucose absorption. These results indicate that ARLP-W has a good therapeutic effect on type 2 diabetes and can assist with further development and application treatment of diabetes.
Subject(s)
Diabetes Mellitus, Experimental/diet therapy , Diabetes Mellitus, Type 2/diet therapy , Dietary Carbohydrates/therapeutic use , Orchidaceae/chemistry , Polysaccharides , Animals , Glucose/chemistry , Male , Mannose/chemistry , Mice , Mice, Inbred C57BL , Polysaccharides/chemistry , Polysaccharides/pharmacologyABSTRACT
Anoectochilus roxburghii, a famous Chinese herbal medicine, has been commonly used for the treatment of liver disease, diabetes, and rheumatoid arthritis. Our study aimed to investigate the anti-rheumatoid arthritis effects of A. roxburghii polysaccharides (ARP), using the rat's model of type II collagen-induced arthritis (CIA). ARP was prepared by alcohol sedimentation and structurally characterized based on combined chemical, chromatographic and spectroscopic methods. High Performance Size Exclusion Chromatography-Multiangle Laser Light Scattering-Refrative Index (HPSEC-MALLS-RI) analysis revealed that ARP includes two peaks, and the weight-average molecular weight (Mw) of the principal one was estimated as 5.90â¯kDa with a relative content of 98.2%. Pharmacological results exhibited that ARP significantly decreased the arthritis index and ameliorated the inflammatory cell infiltration and the synovial tissue destruction in CIA rats. Additionally, ARP possessed significant NO production inhibitory effects and antioxidant activity. Further anti-inflammatory mechanism investigations indicated that ARP significantly inhibited the activation of nuclear factor κB (NF-κB) pathway by suppressing the phosphorylation of IκB and p65, which subsequently down-regulated the mRNA expressions of IL-1ß and IL-6 in LPS-stimulated RAW 264.7 cells. These findings suggested that ARP has great potential in the development of functional foods and dietary supplements for the treatment of rheumatoid arthritis.
