This study was aimed at investigating the hypoglycemic and hypolipidemic effects of a polysaccharide (RTFP) isolated from Rosa roxburghii Tratt fruit on type-2 diabetic db/db mice. The results indicated that the oral administration of RTFP could significantly decrease the body weight, fat, and liver hypertrophy and the levels of fasting blood glucose, serum insulin, and serum lipids of the db/db mice. Histopathological observation showed that RTFP could effectively protect the pancreas, liver, and epididymal fat against damage and dysfunction. Real-time quantitative polymerase chain reaction analysis confirmed that the gene expression levels of peroxisome proliferator-activated receptors-γ (PPAR-γ), sterol regulatory element-binding protein-1 (SREBP-1c), acetyl-CoA carboxylase-1 (ACC-1), fatty acid synthase (FAS), and glucose-6-phosphatase (G6 Pase) were significantly down-regulated in the liver of db/db mice after treatment with RTFP. Moreover, RTFP treatment reversed gut dysbiosis by lowering the Firmicutes-to-Bacteroidetes ratio and enhancing the relative abundances of beneficial bacteria including Bacteroidaceae, Bacteroidaceae S24-7 group, and Lactobacillaceae. These findings suggest that RTFP can be used as a promising functional supplement for the prevention and treatment of type-2 diabetes mellitus.

Tris(2-chloroisopropyl) phosphate (TCPP), a widely used organophosphate flame retardant, has been recognized as an important atmospheric pollutant. It is notable that TCPP has potential for long-range atmospheric transport. However, its atmospheric fate is unknown, restricting its environmental risk assessment. Herein we performed quantum chemical calculations to investigate the atmospheric transformation mechanisms and kinetics of TCPP initiated by ·OH in the presence of O/NO/NO, and the effects of ubiquitous water on these reactions. Results show the H-abstraction pathways are the most favorable for the titled reaction. The calculated gaseous rate constant and lifetime at 298 K are 1.7 × 10 cmmolecule s and 1.7 h, respectively. However, when considering atmospheric water, the corresponding lifetime is about 0.5-20.2 days. This study reveals for the first time that water has a negative role in the ·OH-initiated degradation of TCPP by modifying the stabilities of prereactive complexes and transition states via forming hydrogen bonds, which unveils one underlying mechanism for the observed persistence of TCPP in the atmosphere. Water also influences secondary reaction pathways of selected TCPP radicals formed from the primary H-abstraction. These results demonstrate the importance of water in the evaluation of the atmospheric fate of newly synthesized chemicals and emerging pollutants.

A novel acidic polysaccharide (RTFP-3) was isolated and purified from Rosa roxburghii Tratt fruits. Structural analyses revealed that RTFP-3 is a homogeneous polysaccharide with a molecular weight of 67.2 kDa and mainly consists of arabinose (37.20%), galactose (34.40%), glucose (10.02%) and fucose (18.30%). The structural chain of RTFP-3 was proven to be composed of →6)-α-d-Galp-(1→, →4)-α-d-GalpA-(1→, →5)-α-l-Araf-(1→, →4)-β-d-Glcp-(1→, β-d-Glcp-(1→ and →3,4)-β-l-Fucp-(1→ residues by periodate oxidation-Smith degradation, methylation, and 1D- and 2D-NMR analyses. Bioassay results showed that RTFP-3 exerted favorable mixed type inhibitory activities against α-glucosidase, and its half inhibitory concentration (IC50) value was determined as 4.15 mg mL-1. RTFP-3 showed static type quenching of the intrinsic fluorescence of α-glucosidase, during which the binding process induced the conformational change of α-glucosidase. These results suggest that RTFP-3 has the potential to be a novel α-glucosidase inhibitory agent for use in functional foods.

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