Study of the effect of thiourea and N-ethyl groups on antibacterial activity of rhodamine-labeled 3,4-HPO iron chelators against Gram (+/−) bacteria
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In the sequence of the work in which we identified functional groups of rhodamine labeled 3,4-HPO chelators that are crucial for their activity against Mycobacterium avium infection we now scrutinize if the same groups are also relevant for the chelators antibacterial activity against Gram (+/−) bacteria. In this new infection scenario, we confirmed that a thiourea linkage and N-ethyl substituents on the xanthene ring are important and there is an advantage of the association of both groups in the molecular framework. In particular, we found that three hexadentate chelators (MRH7, MRH8, and MRH10) inhibit bacterial growth of Staphylococcus (S). aureus ATCC 25923 and S. epidermis ATCC 12228 and one hexadentate chelator (MRH7) also inhibits the growth of Escherichia (E.) coli ATCC 25922.
Keywords3-Hydroxy-4-pyridinone Iron(III) chelator Rhodamine Gram-positive bacteria Gram-negative bacteria Infection
This work received financial support from the European Union (FEDER funds through COMPETE) and National Funds (FCT, Fundação para a Ciência e Tecnologia), under the Partnership Agreement PT2020 through project UID/QUI/50006/2013-POCI/01/0145/FEDER/007265 (LAQV/REQUIMTE), and PTDC/QUI/67915/2006. Programa Operacional Regional do Norte (ON.2—O Novo Norte), under the Quadro de Referência Estratégico Nacional (QREN) and funded by Fundo Europeu de Desenvolvimento Regional (Feder) NORTE-07-0124-FEDER-000066. T. M. also thanks FCT for grant SFRH/BD/79874/2011. To all financing sources, the authors are greatly indebted.
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Conflict of interest
The authors declare that they have no conflict of interest.
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