Abstract Gut bacterial β-glucuronidase (GUS) can reactivate xenobiotics that exert enterohepatic circulation- triggered gastrointestinal tract toxicity. GUS inhibitors can alleviate drug-induced enteropathy and improve treatment outcomes. We evaluated the inhibitory effect of Polygonum cuspidatum Siebold & Zucc. and its major constituents against Escherichia coli GUS (EcGUS), and characterized the inhibitory mechanism of each of the components. Trans-resveratrol 4’-O-β-D-glucopyranoside (HZ-1) and (-)-epicatechin gallate (HZ-2) isolated from P. cuspidatum were identified as the key components and potent inhibitors. These two components displayed strong to moderate inhibitory effects on EcGUS, with Ki values of 9.95 and 1.95 μM, respectively. Results from molecular docking indicated that HZ-1 and HZ-2 could interact with the key residues Asp163, Ser360, Ile 363, Glu413, Glu504, and Lys 568 of EcGUS via hydrogen bonding. Our findings demonstrate the inhibitory effect of P. cuspidatum and its two components on EcGUS, which supported the further evaluation and development of P. cuspidatum and its two active components as novel candidates for alleviating drug-induced damage in the mammalian gut.

The microstructure, mechanical properties and fracture behavior of as-cast Mg-10Gd-3Y-xZn-0.6Zr (x = 0, 0.5, 1 and 2 wt%) alloys have been investigated by X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM) and tensile tests. The experimental results reveal that the microstructure of the alloy without Zn contains α-Mg and Mg24(Gd,Y)5 phase, the microstructure of the alloy with 0.5% Zn contained of α-Mg, (Mg,Zn)3(Gd,Y) and Mg24(Gd,Y,Zn)5 phase, whereas when Zn content was 1% and 2%, the Mg12(Gd,Y)Zn phase and some needle-shaped stacking faults notably appear and the Mg24(Gd,Y,Zn)5 phases completely disappear. Moreover, a new 18R long period stacking ordered (LPSO) phase is observed in grain boundaries with increasing Zn content up to 2%. The tensile tests indicate that the alloy containing 0.5% Zn shows the optimal mechanical properties and the ultimate tensile strength (UTS), yield strength (YS) and elongation are 228MPa, 172MPa and 5.1%, respectively. As indicated by fracture analyses, the fracture modes of the alloys with 0%, 1% and 2% Zn are brittleness transcrystalline fracture, and the tensile fracture mode of 0.5% Zn alloy is typical tough transgranular fracture.

The effects of production system on welfare traits, growth performance and meat quality of ducks were explored. A total of 120 newly hatched ducklings were randomly assigned to three groups: i) floor-reared system (FRS); ii) welfare-reared system (WRS) and iii) net-reared system (NRS) (n = 8 ducklings/pen, 5 pens/group). In the FRS, ducks were reared on sawdust bedding that was changed every 2 - 3 days. The WRS was similar to the FRS, the difference being the addition of environmental enrichment devices such as perches, coloured balloons and ribbons. In the NRS, ducks were reared on plastic nets on a bamboo bed, and their droppings were cleaned daily with water. After 35 d, welfare traits, growth performance and meat quality of the ducks were measured. Moving and playing durations of WRS ducks were longer than FRS and NRS ducks. Bathing and feather pecking durations of NRS ducks were longer than FRS and WRS ducks. Duck feather quality was greater and gait defects were reduced in NRS system compared with FRS and WRS systems. Fluctuating asymmetry (FA) was not affected by the production system. Growth performance was not significantly different between FRS and WRS systems. Average daily weight gain of FRS ducks was higher than in NRS ducks. Feed conversion ratio of FRS ducks was lower than in NRS ducks. There was no difference in acidity, conductivity of pectoralis and leg muscle, and drip loss among the production systems. The conclusion was that NRS proved to be the best production system on welfare traits, while WRS and FRS were the best production systems on growth performance.