Heat treatment enhances the plant phenolic (+)-catechin, a weak antimicrobial agent when combined with copper sulphate

Holloway, A. C., Mueller-Harvey, I., Gould, S. W. J., Fielder, M. D., Naughton, D. P. and Kelly, A. P. (2015) Heat treatment enhances the plant phenolic (+)-catechin, a weak antimicrobial agent when combined with copper sulphate. Letters in Applied Microbiology, 61(4), pp. 381-389. ISSN (print) 0266-8254

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Abstract

The aim of the study was to compare the antimicrobial activities of freshly-made, heat-treated (HT), and 14 d stored (+)-Catechin solutions with (+)-catechin flavanol isomers in the presence of copper sulphate. (+)-Catechin activity was investigated when combined with different ratios of Cu(2+) ; 100°C heat treatment; autoclaving; and 14 d storage against Staphylococcus aureus. Cu(2+) -(+)-Catechin complexation, isomer structure-activity relationships, and H2 O2 generation were also investigated. Freshly-made, HT, and 14d stored flavanols showed no activity. Whilst combined Cu(2+) -autoclaved (+)-Catechin and -HT(+)-Catechin activities were similar, HT(+)-Catechin was more active than either freshly-made (+)-catechin (generating more H2 O2 ) or (-)-Epicatechin (though it generated less H2 O2 ) or 14d-(+)-Catechin (which had similar activity to Cu(2+) controls - though it generated more H2 O2 ). When combined with Cu(2+) , in terms of rates of activity, HT(+)-Catechin was lower than (-)-Epigallocatechin gallate and greater than freshly-made (+)-Catechin. Freshly-made and HT(+)-Catechin formed acidic complexes with Cu(2+) as indicated by pH and UV-vis measurements although pH changes did not account for antimicrobial activity. Freshly-made and HT(+)-Catechin both formed Cu(2+) complexes. The HT(+)-Catechin complex generated more H2 O2 which could explain its higher antimicrobial activity. This article is protected by copyright. All rights reserved.

Item Type: Article
Research Area: Biological sciences
Faculty, School or Research Centre: Faculty of Science, Engineering and Computing > School of Life Sciences
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Depositing User: Automatic Import Agent
Date Deposited: 14 Aug 2015 15:05
Last Modified: 01 Feb 2017 03:31
URI: http://eprints.kingston.ac.uk/id/eprint/32230

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