| Plant extract contains a great variety of active constituents, thus it has antibacterial, antioxidant, regulating metabolism activities, and so on. In addition, it is free of residue and resistance. According to that, plant extract is regarded as one of the ideal substitutes for antibiotics. Due to the residue and resistance of antibiotics in animal production, the objective of this paper was to select the components of compound plant extracts from different nature plants by the in vitro antibacterial or antioxidant experiments, then evaluate the safety and application effects of the compound extracts on mouse. The results would provide the scientific evidence for the application of the compound plant extracts in animal production.The main results were as follows:1. The selection, extraction and in vitro antibacterial and antioxidant studies of different plantsSeventeen plants were selected to prepare the water extracts respectively by the method of microwave-assisted extraction, condensed to contain0.5g/ml starting material, and detected by in vitro antibacterial and antioxidant experiments. The results of the antibacterial experiments showed that schisandra fruit (WWZ) and evodia rutaecarpa (WZY) exhibited better inhibitory property against Escherichia Coli C83912, Streptococcus and Salmonella paratyphoid, namely two strains were isolated from the pigs, than others panlt extracts, and the inhibitory ratios of WWZ to the above strains were100%,91%and100%respectively, and the inhibitory rates of WZY were34%,14%and91%respectively. The inhibitory activities of other plant extracts were very low or not detected. The results of antioxidant experiments showed that pomegranate rind (SLP) and argy wormwood leaf (AY) exhibited the higher antioxidant activity than the others, and the half maximal inhibitory concentration of a substance (IC50) of them were1.64mg/ml and6.19mg/ml respectively. IC50of the other plant extracts were ranging from10.10mg/ml to152.54mg/ml. 2. The combination and analysis of functional activated components of compound plant extractsAccording to the above results, WWZ and WZY exhibiting better inhibitory property AY and SLP exhibiting higher antioxidant activity were selected to be the starting materials of the compound plant extracts. The four plant materials were combined with orthogonal combination design L9(43), and then extracted and measured the antibacterial and antioxidant activities by the above methods. According to the results, two optimal compounds were deduced,which were AY:SLP:WWZ:WZY=3:1:9:9(Fl) and AY: SLP:WWZ:WZY=3:9:9:9(F2), respectively. The results of antibacterial experiment showed that the minimum inhibitory concentrations (MIC) of F1extract to Escherichia Coli, Streptococcus and Salmonella paratyphoid, were500mg/ml,250mg/ml and250mg/ml respectively; the MIC of F2extract were250mg/ml,500mg/ml and500mg/ml respectively. The results of antioxidant experiment showed that the IC50of F1and F2extract were6.46mg/ml and3.63mg/ml, respectively.The contents of total phenols (TP), total polysaccharides (TPS), total flavones (TF) and total organic acids (TOA) in the two compounds were determined through Folin-Ciocaileu method, phenol-sulphuric acid method, NaNO2-Al(NO3)3method and electric titration method, respectively. The results showed that Fl extract contains8.02%TP,1.74%TPS,10.38%TF and9.71%TOA, and F2extract contains10.63%,2.16%,8.02%and7.31%, respectively.3. The safety evaluation of compound plant extractsAccording to Horn method recommended by GB15193.3-2003, the safety evaluation of Fl, F2and four starting extracts was conducted with a little modification. The mice were given F1,F2,AY, SLP, WWZ and WZY once orally at60,600and6000mg·kg-1·bw-1, respectively. The results showed that the LD50of all extracts were not detected. Other125ICR healthy female mice (11-13g) were taken and5of them were orally administrated with saline as the control group. The other120mice were divided evenly to6treatments, each treatment contained4doses including111,333,1000,3000mg·kg-1·bw-1. The experimental period was14days. The results showed that no significant difference was found between any treatment group and the control group. Compared with the control, daily weight gain and feed conversion rate of mice orally administered F1and F2extracts exhibited an increasing tendency, especially in the doses groups of1000mg·kg-1·bw-1.4. Application of the compound plant extracts in mouse80Balb/c healthy female mice (11-13g) were divided into5groups containing the control, model, antibiotic, F1and F2groups, respectively. Mice in control group were orally administrated with saline every day, and no more else treating was taken. Mice in model group were orally administrated with saline every day and intraperitoneal injected with cyclophosphamide (CY) every four days to make immunosuppressive model. Antibiotics group were orally administered with chlortetracycline every day at dose of50mg·kg-1·bw-1excepting the treatment of CY. Fl and F2groups were orally administered with F1and F2at dose of1000mg·kg-1·bw-1respectively excepting the treatment of CY. The doses of CY were both100mg·kg-1·bw-1for the former two times, both50mg·kg-1·bw-1for the letter two times. The experiment was conducted for14days, and the growth performances were recorded in the whole experimental stage. At the fourteenth day, eight mice per group were slaughtered, and their samples were gotten and the immune indices and antioxidant indices were studied. The results exhibited that, compared with control group, daily weight gain, feed conversion rate, spleen index, thymus index, liver catalase (CAT) activity and liver total antioxidant capacity (T-AOC) of model group were all significantly increased (P<0.05), while MDA content in liver was opposite the former (P<0.05). Compared with model group, liver superoxide dismutase (SOD) activity, liver CAT activity and liver T-AOC in Fl group and F2group were both increased (P<0.05), and MDA content in liver was opposite the former (P<0.05). Besides, the spleen index of Fl group was increased significantly. Compared with antibiotic group, there were no significant difference in daily weight gain, feed conversion rate, thymus index in Fl group and F2group (P<0.05). Spleen index of F1was increased significantly (P<0.05). The SOD activity, CAT activity and T-AOC in liver in both F1group and F2group were significantly increased (P<0.05), and MDA content in liver was opposite the former (P<0.05). The other mice in each group were intraperitoneal injected with Escherichia coli, and then continued to administer those substance orally as before. The mortality and diarrhea rate in forty eight hours after the injection were recorded. The result showed that the diarrhea rates of the F1, F2,antibiotic, model and control groups were25%、75%、25%、66.6%and25%especially, and the mortality of which were0%、37.5%、0%、33.3%and0%especially.In a word, two plant compounds composed of argy wormwood leaf, pomegranate rind, schisandra fruit and evodia rutaecarpa were obtained by in vitro antibacterial and antioxidant experiments, and performed the safety evaluation and application effects on mouse as the test of animals. The results showed that one of the two compounds could significantly increase growing performances and improve antioxidant capacity, immune function, anti-coli infection capacity in immunosuppressive mice. |
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