Concentration-Dependent Multi-Potentiality of L-Arginine: Antimicrobial Effect, Hydroxyapatite Stability, and MMPs Inhibition.

Mohammed Nadeem Bijle,Muneer Gohar Babar,Abhishek Parolia,Umer Daood,Mallikarjuna Rao Pichika,Cynthia Yiu,Kit-Kay Mak

doi:10.3390/molecules26216605

Mohammed Nadeem Bijle, Muneer Gohar Babar + Show 5 more

Open Access

https://doi.org/10.3390/molecules26216605

Copy DOI

Abstract

This study’s objective was to examine L-arginine (L-arg) supplementation’s effect on mono-species biofilm (Streptococcus mutans/Streptococcus sanguinis) growth and underlying enamel substrates. The experimental groups were 1%, 2%, and 4% arg, and 0.9% NaCl was used as the vehicle control. Sterilised enamel blocks were subjected to 7-day treatment with test solutions and S. mutans/S. sanguinis inoculum in BHI. Post-treatment, the treated biofilms stained for live/dead bacterial cells were analysed using confocal microscopy. The enamel specimens were analysed using X-ray diffraction crystallography (XRD), Raman spectroscopy (RS), and transmission electron microscopy (TEM). The molecular interactions between arg and MMP-2/MMP-9 were determined by computational molecular docking and MMP assays. With increasing arg concentrations, bacterial survival significantly decreased (p < 0.05). The XRD peak intensity with 1%/2% arg was significantly higher than with 4% arg and the control (p < 0.05). The bands associated with the mineral phase by RS were significantly accentuated in the 1%/2% arg specimens compared to in other groups (p < 0.05). The TEM analysis revealed that 4% arg exhibited an ill-defined shape of enamel crystals. Docking of arg molecules to MMPs appears feasible, with arg inhibiting MMP-2/MMP-9 (p < 0.05). L-arginine supplementation has an antimicrobial effect on mono-species biofilm. L-arginine treatment at lower (1%/2%) concentrations exhibits enamel hydroxyapatite stability, while the molecule has the potential to inhibit MMP-2/MMP-9.

Highlights

Oral biofilms are significant to both the health and disease state
The confocal laser scanning microscopy (CLSM) images of S. mutans and S. sanguinis biofilms treated with the control 0.9% NaCl are shown in Figure 1A,B, respectively
The 1% arg-treated specimens appeared with dead S. mutans bacterial colonies with few areas of surviving green-stained bacteria (Figure 1C)

Summary

Introduction

Oral biofilms are significant to both the health and disease state. The shift from homeostasis to biofilm dysbiosis is inceptive to the pathological state of chronic biofilmmediated diseases such as dental caries [1,2]. Cariogenic biofilms are dominant with aciduric pathogens such as Streptococcus mutans (dysbiosis state), as their pathogenicity is dependent on frequent exposure to fermentable carbohydrates, leading to prolonged biofilm acidification and net mineral loss in dental enamel [3,4]. Indiscriminate use of anti-microbials to counter pathogenic biofilms has led to antimicrobial resistance [5,6]. The failure of anti-microbials to prevent the growth of deep-embedded pathogens through biofilms with extra-cellular polymeric substances (EPS) as a biofilm matrix constitutes the rationale for this study. Strategies are needed that combat the limitations of anti-microbials

Objectives

Methods

Results

Conclusion