Contribution of the R8 substituent to the in vitro antibacterial potency of besifloxacin and comparator ophthalmic fluoroquinolones

Wolfgang Haas, Christine M Sanfilippo, Christine K Hesje, Timothy W Morris Department of Microbiology and Sterilization Sciences, Bausch + Lomb, Inc, Rochester, NY, USA Introduction: Previous work has shown that besifloxacin, an 8-chloro-fluoroquinolone, has more potent activity against gram-positiv...

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Autores principales:	Haas W, Sanfilippo CM, Hesje CK, Morris TW
Formato:	article
Lenguaje:	EN
Publicado:	Dove Medical Press 2013
Materias:	Ophthalmology RE1-994
Acceso en línea:	https://doaj.org/article/f9762f88eb7a4c4fb3c941968679e0f2
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spelling	oai:doaj.org-article:f9762f88eb7a4c4fb3c941968679e0f22021-12-02T00:58:47ZContribution of the R8 substituent to the in vitro antibacterial potency of besifloxacin and comparator ophthalmic fluoroquinolones1177-54671177-5483https://doaj.org/article/f9762f88eb7a4c4fb3c941968679e0f22013-05-01T00:00:00Zhttp://www.dovepress.com/contribution-of-the-r8-substituent-to-the-in-vitro-antibacterial-poten-a12948https://doaj.org/toc/1177-5467https://doaj.org/toc/1177-5483Wolfgang Haas, Christine M Sanfilippo, Christine K Hesje, Timothy W Morris Department of Microbiology and Sterilization Sciences, Bausch + Lomb, Inc, Rochester, NY, USA Introduction: Previous work has shown that besifloxacin, an 8-chloro-fluoroquinolone, has more potent activity against gram-positive pathogens than moxifloxacin and gatifloxacin, which carry an 8-methoxy group. This study was conducted to determine the contribution of the R7 and R8 substituent to fluoroquinolone antibacterial activity. Materials and methods: Besifloxacin, moxifloxacin, gatifloxacin, their R8 structural analogs, and ciprofloxacin were tested against representative isolates of various gram-positive and gram-negative species and previously characterized fluoroquinolone-resistant mutants of Staphylococcus aureus. Minimum inhibitory and minimum bactericidal concentrations were determined according to Clinical and Laboratory Standards Institute (CLSI) guidelines. Reserpine was used to determine the effect of efflux pumps on antibacterial activity. Results: In general, exchanging the R8 residue in besifloxacin slightly reduced the molecule's potency, while introducing an 8-chloro group in moxifloxacin increased its potency. A similar change in gatifloxacin had little to no effect. Substituting the R8 residues did not increase the susceptibility to the efflux pump inhibitor reserpine or result in a loss of bactericidal activity. In contrast, the positive control, ciprofloxacin, was shown to be a substrate for reserpine and lost bactericidal activity against some fluoroquinolone-resistant isolates of S. aureus. Conclusion: The data presented here show that, depending on the R7 substituent, replacing an 8-methoxy group with an 8-chloro substituent can improve potency or can have little-to-no effect. These findings highlight the importance of the interplay between the R7 and R8 substituents in determining antibacterial potency. Keywords: moxifloxacin, besifloxacin, fluoroquinolone analogs, Staphylococcus aureus, resistanceHaas WSanfilippo CMHesje CKMorris TWDove Medical PressarticleOphthalmologyRE1-994ENClinical Ophthalmology, Vol 2013, Iss default, Pp 821-830 (2013)
institution	DOAJ
collection	DOAJ
language	EN
topic	Ophthalmology RE1-994
spellingShingle	Ophthalmology RE1-994 Haas W Sanfilippo CM Hesje CK Morris TW Contribution of the R8 substituent to the in vitro antibacterial potency of besifloxacin and comparator ophthalmic fluoroquinolones
description	Wolfgang Haas, Christine M Sanfilippo, Christine K Hesje, Timothy W Morris Department of Microbiology and Sterilization Sciences, Bausch + Lomb, Inc, Rochester, NY, USA Introduction: Previous work has shown that besifloxacin, an 8-chloro-fluoroquinolone, has more potent activity against gram-positive pathogens than moxifloxacin and gatifloxacin, which carry an 8-methoxy group. This study was conducted to determine the contribution of the R7 and R8 substituent to fluoroquinolone antibacterial activity. Materials and methods: Besifloxacin, moxifloxacin, gatifloxacin, their R8 structural analogs, and ciprofloxacin were tested against representative isolates of various gram-positive and gram-negative species and previously characterized fluoroquinolone-resistant mutants of Staphylococcus aureus. Minimum inhibitory and minimum bactericidal concentrations were determined according to Clinical and Laboratory Standards Institute (CLSI) guidelines. Reserpine was used to determine the effect of efflux pumps on antibacterial activity. Results: In general, exchanging the R8 residue in besifloxacin slightly reduced the molecule's potency, while introducing an 8-chloro group in moxifloxacin increased its potency. A similar change in gatifloxacin had little to no effect. Substituting the R8 residues did not increase the susceptibility to the efflux pump inhibitor reserpine or result in a loss of bactericidal activity. In contrast, the positive control, ciprofloxacin, was shown to be a substrate for reserpine and lost bactericidal activity against some fluoroquinolone-resistant isolates of S. aureus. Conclusion: The data presented here show that, depending on the R7 substituent, replacing an 8-methoxy group with an 8-chloro substituent can improve potency or can have little-to-no effect. These findings highlight the importance of the interplay between the R7 and R8 substituents in determining antibacterial potency. Keywords: moxifloxacin, besifloxacin, fluoroquinolone analogs, Staphylococcus aureus, resistance
format	article
author	Haas W Sanfilippo CM Hesje CK Morris TW
author_facet	Haas W Sanfilippo CM Hesje CK Morris TW
author_sort	Haas W
title	Contribution of the R8 substituent to the in vitro antibacterial potency of besifloxacin and comparator ophthalmic fluoroquinolones
title_short	Contribution of the R8 substituent to the in vitro antibacterial potency of besifloxacin and comparator ophthalmic fluoroquinolones
title_full	Contribution of the R8 substituent to the in vitro antibacterial potency of besifloxacin and comparator ophthalmic fluoroquinolones
title_fullStr	Contribution of the R8 substituent to the in vitro antibacterial potency of besifloxacin and comparator ophthalmic fluoroquinolones
title_full_unstemmed	Contribution of the R8 substituent to the in vitro antibacterial potency of besifloxacin and comparator ophthalmic fluoroquinolones
title_sort	contribution of the r8 substituent to the in vitro antibacterial potency of besifloxacin and comparator ophthalmic fluoroquinolones
publisher	Dove Medical Press
publishDate	2013
url	https://doaj.org/article/f9762f88eb7a4c4fb3c941968679e0f2
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Contribution of the R8 substituent to the in vitro antibacterial potency of besifloxacin and comparator ophthalmic fluoroquinolones

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