Analyses Of Chemical Constituents And Biological Activities Of Giant Panda's Staple Bamboo Leaf Extract

In this study,the leaves of Bashania fargesii in Foping National Nature Reserve of Shaanxi Province were used as research objects to identify the chemical composition of extractions from different ages of bamboo leaf in feeding area of giant pandas(Ailuropoda melanoleuca)and non-feeding areas to find the difference of compositions.The temporal and spatial changes of antioxidant activity in vitro and antibacterial activity of bamboo leaves extracts were also studied.Combined with the changes of biological activity of bamboo leaves extracts,the possible factors affecting the food selection of giant pandas were discussed from the perspective of chemical composition.which provided reference for the breeding management of captive giant pandas and the repurchase selection of wild pandas.Content 1 Establishment of the methodology for preparation of giant panda staple bamboo leaf extract(BLE)The orthogonal extraction test was carried out to determine the extraction method of bamboo leaves with ethyl acetate as solvent.The optimum extraction conditions were as follows: soaking for 8 h,sowing at 90°C for 18 h,the extraction rate was up to 7.54%.The average extraction rate was 4.04%.Content 2 Chemical composition analysis and identification of the main panda bamboo leaf extractThe chemical constituents of Extraction of bamboo leaves in feeding area(FABLE)and Extraction of bamboo leaves in non-feeding area(NFABLE)of giant pandas were identified by Ultra-high performance liquid chromatography-mass spectrometry(UPLC-MS)combined with map databases MassBank,MoNA,Respect and GNPS.The chemical composition can be divided into 12 superclasses according to the chemical structure.Among them,the number of chemical components and compounds in FABLE are higher than that of NFABLE.A total of 9 super-class(84 species)FABLE conserved compounds were not identified in NFABLE,and the difference between phenylpropionic acid and polyketide(PPs)was greater.Plant secondary metabolites(PSMs)in BLE were analyzed.Nine conserved alkaloids were identified in FABLE,of which Hydrocinchonine and Tazettine are alkaloids present only in FABLE.Nine,seven and six unique alkaloids were found in FABLE-1,FABLE-2 and FABLE-3,respectively.Those alkaloids belong to 14 classes such as Lupin alkaloids,Tropane alkaloids and Ergoline and derivatives.124 kinds of conserved PPs were identified in FABLE,belonging to 15 classes such as Tetracyclines,Stilbenes and Phenylpropanoic acids.34,42 and 38 unique PPs were found in FABLE-1,42 FABLE-2 and 38 FABLE-3.Content 3 Biological Activity of Extracts from Giant PandasThe inhibitory effect of young BLE(?2 years)and old BLE(?2 years)on six pathogenic bacteria of giant pandas is determined by the disk diffusion methods,and then compared the diameter of the inhibition zone with 20 antibiotics.The results showed that there was no significant difference in the diameter of the inhibition zone between BLE and 11 antibiotics(P>0.05).Season and altitude jointly affect the inhibitory effect of BLE on Escherichia coli,Salmonella enterica sub sp.arizonae,Klebsiella pneumoniae,and the bacteriostatic effects of BLE in the transitional and wintering season are better than those in mating season.Old BLE,from more than 1700 m,has significantly higher activity against S.enterica sub sp.arizonae than in the 1500 m area during the transition.The activity of the BLE-resistant S.enterica sub sp.arizonae in transition of more than 1700 m was significantly higher than 1500 m.The season significantly affected the inhibitory activity of BLE against Pseudomonas aeruginosa,Salmonella enteritidis,Yersinia enterocolitica(P<0.05),and Salmonella enteritidis at different altitudes BLE The activity exhibits a wave-like change.The results suggest that the food choice of giant pandas may be related to the chemical composition of their food.The vertical migration of giant pandas may be related to the biological activity of the staple bamboo leaves.The unique conserved compounds of feeding area bamboo leaf extract may be one of the factors influencing the food choice of giant pandas.