title: Anti-Escherichia coli O157:H7 properties of purple prairie clover and sainfoin condensed tannins.
abstract: Condensed tannins (CT) from purple prairie clover (PPC; Dalea purpurea Vent.) and sainfoin (SF; Onobrychis viciifolia) were assessed for anti-Escherichia coli activity by comparing their ability to react with proteins and liposome, cause cell aggregation, and alter outer membrane (OM) morphology and permeability. The PPC CT had greater (P < 0.01) protein-precipitating capacity than SF CT using either bovine serum albumin or ribulose 1,5-disphosphate carboxylase as model proteins. Minimum inhibitory concentration of PPC CT for two strains of E. coli and five strains of E. coli O157:H7 was four to six times lower than that of SF CT. E. coli exposed to 10 µg/mL of both CT had higher (P < 0.05) OM permeability than controls and was greater (P < 0.05) for PPC than for SF CT. Addition of both CT at 50 and 200 µg/mL caused cell aggregation which was more evident (P < 0.05) for PPC than for SF CT. Transmission electron microscopy showed electron dense material on the cell surface when cells were exposed to 50 µg/mL of PPC CT. The greater anti-E. coli activity of PPC than SF CT was due to its enhanced ability to precipitate protein that increased OM permeability and promoted cell aggregation.
authors: Department of Veterinary Medicine, Inner Mongolia Agricultural University, Hohhot 010020, China. shiguangnmg@163.com
authors: Xiu-Li
authors: XL
authors: Liu
authors: Yong-Qing
authors: YQ
authors: Hao
authors: Long
authors: L
authors: Jin
authors: Zhong-Jun
authors: ZJ
authors: Xu
authors: Tim A
authors: TA
authors: McAllister
authors: Yuxi
authors: Y
authors: Wang
mesh_terms: D015057:1-Naphthylamine / Q000031:analogs & derivatives / Q000737:chemistry; D000818:Animals; D000900:Anti-Bacterial Agents / Q000302:isolation & purification / Q000494:pharmacology*; D002417:Cattle; D002462:Cell Membrane / Q000187:drug effects / Q000648:ultrastructure; D002463:Cell Membrane Permeability / Q000187:drug effects; D011232:Chemical Precipitation; D019453:Escherichia coli O157 / Q000166:cytology / Q000187:drug effects* / Q000648:ultrastructure; D007887:Fabaceae / Q000737:chemistry*; D005453:Fluorescence; D008081:Liposomes / Q000737:chemistry; D008826:Microbial Sensitivity Tests; D044945:Proanthocyanidins / Q000302:isolation & purification / Q000494:pharmacology*; D012710:Serum Albumin, Bovine / Q000737:chemistry; D029921:Trifolium / Q000737:chemistry*
chemical_list: D000900:Anti-Bacterial Agents; D008081:Liposomes; D044945:Proanthocyanidins; D012710:Serum Albumin, Bovine; C005444:N-phenyl-1-naphthylamine; D015057:1-Naphthylamine
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