RESUMO
Similar to the enzymatic process, there might also be an active fragment in polysaccharides, how to obtain is important for investigating the bioactivity and pharmacological mechanism of polysaccharides. Presently, a Gynostemma pentaphyllum endophytic fungus Chaetomium globosum CGMCC 6882 polysaccharide [Genistein Combined Polysaccharide (GCP)] was degraded by ultrasonic treatment, two polysaccharide fragments of GCP-F1 and GCP-F2 were obtained. Physicochemical results showed that GCP-F1 and GCP-F2 had the same monosaccharide composition of arabinose, galactose, glucose, xylose, mannose, and glucuronic acid as compared to GCP with slightly different molar ratios. However, weight-average molecular weights of GCP-F1 and GCP-F2 decreased from 8.093 × 104 Da (GCP) to 3.158 × 104 Da and 1.027 × 104 Da, respectively. In vitro scavenging assays illustrated that GCP-F1 and GCP-F2 had higher antioxidant activity against 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, superoxide anions, and hydroxyl radical than GCP, the order was GCP < GCP-F1 < GCP-F2. Meanwhile, antibacterial tests showed that ultrasonic degradation increased the antibacterial activity of GCP-F1 as compared to GCP, but GCP-F2 almost lost its antibacterial activity with further ultrasound treatment. Changes in the antioxidant and antibacterial activities of GCP-F1 and GCP-F2 might be related to the variation of their molecular weights.
RESUMO
Researchers have investigated the role of polysaccharides in disease treatment via gut microbiota regulation but ignore their function in disease prevention and physique enhancement. In this work, a Gynostemma pentaphyllum polysaccharide (GPP) was tested by methyl thiazolyl tetrazolium (MTT) assay and proved to be safe to Caco-2 cells. Animal experiments showed that the administration of GPP for 3 weeks decreased the body weight gain of mice from 15.4 ± 1.7 to 12.2 ± 1.8 g in a concentration-dependent manner. Analysis of short-chain fatty acids (SCFAs) indicated that GPP increased the levels of acetate, propionate, butyrate, and total SCFAs in the cecum contents of normal mice. Furthermore, GPP improved the species richness and abundance in the gut microbiota but reduced the Firmicutes/Bacteroidetes ratio from 0.8021 to 0.3873. This work provides a basis for incorporating GPP into diet to prevent or mitigate the occurrence of obesity via gut microbiota regulation.
RESUMO
Hepatic iron overload is a universal phenomenon in patients with myelodysplastic syndromes (MDS) who undergo bone marrow transplantation and may experience the toxicity of peri- and post-bone marrow transplantation. To clarify the mechanisms of iron overload-triggered liver injury, we determined the effects of iron overload on changes in protein phosphorylation in human hepatocyte cell line HH4 in vitro by using a phosphoproteomics approach. The hepatocytes were exposed to high concentrations of ferric ammonium citrate (FAC) to build up an iron overload model in vitro. Changes in protein phosphorylation initiated by iron overloading were studied by 2D-LC/MS. We identified 335 differentially expressed phosphorylated proteins under the condition of excess hepatocyte iron, 11% of which were related to cell cycle progression. The results of phosphoproteomics showed that iron overload induced 10.9 times increase in Thr 14/Tyr 15-phosphorylated Cdk1 in HH4 cells. Flow cytometry analysis revealed that FAC-treated HH4 cells showed significant G2/M phase arrest. Our subsequent RT-PCR and Western blot experiments indicated that FAC-induced G2/M phase arrest was related to the activation of p53-p21-Cdk1, p53-14-3-3 sigma-Cdk1, and 14-3-3 gamma pathway. Our findings demonstrate the first evidence that iron overload causes G2/M arrest in HH4 hepatocytes.
