Effects of daidzein on antioxidant capacity in weaned pigs and IPEC-J2cells

Our previous study found that soybean isoflavones in soybean meal play an important role in improving growth performance and antioxidant capacity in pigs.However,it is still unknown whether long-term supplementation with daidzein,an active molecule deglycosylated from daidzin,in a corn-soybean meal diet can enhance growth performance in pigs.Thus,in the present study,an animal trial was carried out to investigate the effects of dietary supplementation with daidzein on the growth performance and antioxidant capacity of pigs.A total of 80 weaned piglets(40 barrows and 40 females)were assigned to 4treatments with 5 pens per treatment and 4 piglets per pen and fed a diet supplemented with 0,25,50 and 100 mg/kg daidzein for a 72-day trial.In addition,porcine intestinal epithelial cells(IPEC-J2)were used as an in vitro model to explore the underlying antioxidant mechanisms of daidzein.IPEC-J2 cells were treated with 0.6 mM hydrogen peroxide(H_(2)O_(2))in the presence or absence of 40μM daidzein.The results showed that adding 50 mg/kg of daidzein to the diet significantly improved body weight on day72,average daily gain(ADG)during days 0 to 72 and plasma superoxide dismutase(SOD)activity on day42,and decreased malondialdehyde(MDA)content on day 14(P<0.05).Treatment with 0.6 m M H_(2)O_(2)for 1 h significantly decreased cell viability and catalase(CAT)activity and increased intracellular reactive oxygen species(ROS)levels and MDA content(P<0.05),while pretreatment with 40μM daidzein prevented the decrease in cell viability and CAT activity and the increase in intracellular ROS levels and MDA content caused by H_(2)O_(2)(P<0.05).In addition,H_(2)O_(2)stimulation significantly suppressed the expression of nuclear factor erythroid-2-related factor 2(Nrf2),CAT,occludin and zonula occludens-1(ZO-1),while pretreatment with daidzein preserved the expression of Nrf2,CAT and occludin in H_(2)O_(2)-stimulated IPEC-J2 cells(P<0.05).In conclusion,our results suggested that long-term dietary supplementation with 50 mg/kg daidzein improved growth performance in pigs and was beneficial to the antioxidant capacity of pigs.Daidzein exerted protective effects against H_(2)O_(2)-induced oxidative stress in IPEC-J2 cells and the underlying mechanism may be related to the activation of the Nrf2 signaling pathway.

Heterologous expression and characterization of man gene from Bacillus Subtilis in Pichia Pastoris

β-Mannanase catalyzes endo-wise hydrolysis of the backbone of mannan and heteromannan,which are abun-dant in the cell wall structure of ungerminated leguminous seeds.The mature β-mannanase originated from Bacillus subtilis was expressed in Pichia pastoris,a methylotrophic yeast,using the leader peptide sequence of Saccharomyces cerevisiae α-factor.The cultivation of β-mannanase express-ing Pichia pastoris yields up to 1.8 g/L protein.In the super-natant the activity of the 40 kDa—total mannanase attained a level of 1102.0 IU/mL.The properties of the β-mannanase were characterized.Optimum pH and temperature for the recombinant enzyme were 5.5 and 50℃ respectively.The enzyme was stable at pH 5.0-10.0 and maintained over 30%original activity after incubating at 70℃ for 30 min.