Molecules 2013, 18(2), 2183-2199; doi:10.3390/molecules18022183
Article

Anti-Escherichia coli O157:H7 Properties of Purple Prairie Clover and Sainfoin Condensed Tannins

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Received: 21 December 2012; in revised form: 31 January 2013 / Accepted: 31 January 2013 / Published: 8 February 2013
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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.
Keywords: condensed tannins; E. coli; outer membrane; cell aggregation; protein precipitation
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MDPI and ACS Style

Liu, X.-L.; Hao, Y.-Q.; Jin, L.; Xu, Z.-J.; McAllister, T.A.; Wang, Y. Anti-Escherichia coli O157:H7 Properties of Purple Prairie Clover and Sainfoin Condensed Tannins. Molecules 2013, 18, 2183-2199.

AMA Style

Liu X-L, Hao Y-Q, Jin L, Xu Z-J, McAllister TA, Wang Y. Anti-Escherichia coli O157:H7 Properties of Purple Prairie Clover and Sainfoin Condensed Tannins. Molecules. 2013; 18(2):2183-2199.

Chicago/Turabian Style

Liu, Xiu-Li; Hao, Yong-Qing; Jin, Long; Xu, Zhong-Jun; McAllister, Tim A.; Wang, Yuxi. 2013. "Anti-Escherichia coli O157:H7 Properties of Purple Prairie Clover and Sainfoin Condensed Tannins." Molecules 18, no. 2: 2183-2199.


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