Anti-Bacterial Activity of Phenolic Compounds against Streptococcus pyogenes

Type Article
Date 2017-06
Language English
Author(s) Macé SabrinaORCID1, Truelstrup Hansen Lisbeth2, Rupasinghe H. P. Vasantha3
Affiliation(s) 1 : Department of Plant, Food, and Environmental Sciences, Faculty of Agriculture, Dalhousie University, Truro, NS B2N 5E3, Canada
2 : Department of Process Engineering and Applied Science, Faculty of Engineering, Dalhousie University, Halifax, NS B3H 4R2, Canada
3 : Department of Pathology, Faculty of Medicine, Dalhousie University, Halifax, NS B3H 4H7, Canada
Source Medicines (2305-6320) (MDPI AG), 2017-06 , Vol. 4 , N. 2 , P. 25 (9p.)
DOI 10.3390/medicines4020025
Note This article belongs to the Special Issue Antimicrobial, Antioxidant and Anti-inflammatory Activities of Essential Oils
Keyword(s) pharyngitis, strep throat, biofilm, naphthoquinone, infection, disease, polyphenols

Background: Worldwide, Streptococcus pyogenes is the leading cause of bacterial pharyngitis. To reduce the use of antibiotics, antimicrobial phytochemical-containing remedies, which have long been in use in traditional medicine, may provide new approaches for management of streptococcal pharyngitis. The objective of this study was to assess the inhibitory activities of 25 natural phenolic compounds against three strains of S. pyogenes. Methods: After an initial screening, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the nine most effective phenolic compounds were determined. The effect of four compounds with the lowest MIC and MBC on streptococcal growth and biofilm formation was also studied. Results: 1,2-Naphthoquinone and 5-hydroxy-1,4-naphthoquinone elicited the greatest anti-S. pyogenes activities with MICs ranging from 0.39 to 6.25 µg mL−1 and MBCs of 100 µg mL−1. Both naphthoquinones inhibited the biofilm formation at concentrations ranging from 12.5 to 50 µg mL−1. Biofilm reduction and altered bacterial cell structures were visible in scanning electron microscopy images of naphthoquinone-treated cells. Conclusion: In conclusion, 1,2-naphthoquinone and 5-hydroxy-1,4-naphthoquinone inhibit S. pyogenes and should be further investigated as candidates for the management of streptococcal pharyngitis.

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