Bactericidal and Anti-Biofilm Activity of Ethanol Extracts Derived from Selected Medicinal Plants against Streptococcus pyogenes.

Niluni Wijesundara,H Rupasinghe

doi:10.3390/molecules24061165

Abstract

Background: There is a growing interest in medicinal plants which have been traditionally used for the treatment of human infections. This study assessed 14 ethanol extracts (EEs) on bacterial growth and biofilm formation of Streptococcus pyogenes. Methods: Constituent major phytochemicals in the extracts were identified using ultra performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS/MS). Micro-broth dilution and time-kill assays were used to determine antibacterial activities. Anti-biofilm activities were studied using MTT assay, and morphology of biofilms was observed by scanning electron microscopy (SEM). Transmission electron microscopy (TEM) was employed to visualize the ultra-cross section structure of bacteria treated with efficacious extracts. Results: Licorice root, purple coneflower flower, purple coneflower stem, sage leaves and slippery elm inner bark EEs were the most effective, with minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of 62.5 μg/mL and 125 μg/mL, respectively. The minimum biofilm inhibitory concentration (MBIC) of extracts ranged from 31.5–250 μg/mL. Morphological changes were observed in treated biofilms compared to the untreated. The four most effective extracts exhibited the ability to induce degradation of bacterial cell wall and disintegration of the plasma membrane. Conclusion: We suggest that EEs of sage leaf and purple coneflower flower are promising candidates to be further investigated for developing alternative natural therapies for the management of streptococcal pharyngitis.

Highlights

IntroductionIt is the major bacterial cause of pharyngitis which is responsible for about
Streptococcus pyogenes, called group A streptococcus (GAS), is one of the most important aGram-positive cocci
We report the inhibitory effect on the growth and biofilm formation of S. pyogenes by phytochemical-rich ethanol extracts derived from selected Canadian traditional medicinal plants, emphasizing their importance as an alternative treatment

Summary

Introduction

It is the major bacterial cause of pharyngitis which is responsible for about. The symptoms of streptococcal pharyngitis could overlap with viral pharyngitis; it is important to confirm GAS pharyngitis by proper diagnosis test before prescribing antibiotic therapy. Over-prescribing of antibiotics for pharyngitis is a growing concern that could lead to antibiotic resistance [5,6]. There is a growing interest in medicinal plants which have been traditionally used for the treatment of human infections. This study assessed 14 ethanol extracts (EEs) on bacterial growth and biofilm formation of Streptococcus pyogenes. MTT assay, and morphology of biofilms was observed by scanning electron microscopy (SEM). Transmission electron microscopy (TEM) was employed to visualize the ultra-cross section structure of bacteria treated with efficacious extracts. Results: Licorice root, purple coneflower flower, purple coneflower stem, sage leaves and slippery elm inner bark EEs were the most effective, with minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of 62.5 μg/mL and

Methods

Results

Discussion

Conclusion