Synergistic in vitro antimicrobial activity of pomegranate rind extract and zinc (II) against Micrococcus luteus under planktonic and biofilm conditions

Celiksoy, Vildan, Moses, Rachael L., Sloan, Alastair J. ORCID: https://orcid.org/0000-0002-1791-0903, Moseley, Ryan ORCID: https://orcid.org/0000-0002-2812-6735 and Heard, Charles M. ORCID: https://orcid.org/0000-0001-9703-9777 2021. Synergistic in vitro antimicrobial activity of pomegranate rind extract and zinc (II) against Micrococcus luteus under planktonic and biofilm conditions. Pharmaceutics 13 (6) , 851. 10.3390/pharmaceutics13060851

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Abstract

Infectious diseases caused by microbial biofilms are a major clinical problem, and new antimicrobial agents that can inhibit biofilm formation and eradicate pre-formed biofilms are urgently needed. Pomegranate extracts are a well-established folkloric medicine and have been used in the treatment of infectious diseases since ancient times, whilst the addition of metal ions, including zinc (II), has enhanced the antimicrobial activity of pomegranate. Micrococcus luteus is generally a non-pathogenic skin commensal bacterium, although it can act as an opportunistic pathogen and cause serious infections, particularly involving catheterization and comorbidities. The aims of this study were to evaluate the holistic activity of pomegranate rind extract (PRE), Zn (II), and PRE/Zn (II) individually and in combination against M. luteus under both planktonic and biofilm conditions. Antimicrobial activity was detected in vitro using the broth dilution method, and synergistic activity was determined using checkerboard and time-kill assays. Effects on biofilm formation and eradication were determined by crystal violet and BacLightTM Live/Dead staining. PRE and Zn (II) exerted antimicrobial activity against M. luteus under both planktonic and biofilm conditions. After 4 h, potent synergistic bactericidal activity was also found when PRE and Zn (II) were co-administered under planktonic conditions (log reductions: PRE 1.83 ± 0.24, Zn (II) 3.4 ± 0.08, and PRE/Zn (II) 6.88 ± 1.02; p < 0.0001). In addition, greater heterogeneity was induced in the structure of M. luteus biofilm using the PRE/Zn (II) combination compared to when PRE and Zn (II) were applied individually. The activity of PRE and the PRE/Zn (II) combination could offer a novel antimicrobial therapy for the treatment of disease-associated infections caused by M. luteus and potentially other bacteria.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Dentistry Pharmacy
Additional Information:	This is an open access article distributed under the Creative Commons Attribution License
Publisher:	MDPI
ISSN:	1999-4923
Date of First Compliant Deposit:	11 June 2021
Date of Acceptance:	31 May 2021
Last Modified:	05 May 2023 10:31
URI:	https://orca.cardiff.ac.uk/id/eprint/141882

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