Biological and Pharmaceutical Bulletin
Online ISSN : 1347-5215
Print ISSN : 0918-6158
ISSN-L : 0918-6158
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Lacunary-Substituted Undecatungstosilicates Sensitize Methicillin-Resistant Staphylococcus aureus to β-Lactams
Yutaka TAJIMA
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2001 Volume 24 Issue 9 Pages 1079-1084

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Abstract

Some Keggin-structural (hetero)polyoxotungstates with a lacunary hole, such as undecatungstosilicate ([SiW11O39]8-, SiW11), greatly sensitize methicillin-resistant Staphylococcus aureus (MRSA) to β-lactams. In this study, the effects of lacunary-substituted derivatives of SiW11 were tested to determine if the lacunary hole is required for the sensitizing effect. Initially, it was supposed that the hole functioned as a binding site that interacts with some bacterial components. However, most of the lacunary-substituted species had stronger effects than SiW11, indicating that the hole is not essential for the sensitizing effect. Undecatungsto(ferri)ferrosilicate ([SiW11O39Fe]6/5-) was the most potent compound tested, but undecatungstocobaltosilicate ([SiW11O39Co]6-) gave better results according to the fractional inhibitory concentration index. Small lipophilic cations enhanced the sensitizing effect, but bulky cations inhibited it. This suggests that a charge interaction between the tungsten compounds and some unknown materials in the culture medium or bacterial cells plays an important role in the sensitizing effect.

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© 2001 The Pharmaceutical Society of Japan
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