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Open Access Research article

Effects of mushroom and chicory extracts on the shape, physiology and proteome of the cariogenic bacterium Streptococcus mutans

Caterina Signoretto1*, Anna Marchi1, Anna Bertoncelli1, Gloria Burlacchini1, Alberto Milli1, Francesco Tessarolo2, Iole Caola3, Adele Papetti4, Carla Pruzzo5, Egija Zaura6, Peter Lingström7, Itzhak Ofek8, David A Spratt9, Jonathan Pratten9, Michael Wilson9 and Pietro Canepari1

Author Affiliations

1 Dipartimento di Patologia e Diagnostica – Sezione di Microbiologia, Università di Verona, Strada Le Grazie 8, Verona, 37134, Italy

2 Centro Interdipartimentale di Tecnologie Biomediche (BIOtech), Università di Trento, Via delle Regole 101, Mattarello, Trento, 38123, Italy

3 Sezione di Microscopia Elettronica, Dipartimento di Medicina di Laboratorio, APSS, Trento, 38100, Italy

4 Dipartimento di Scienze del Farmaco, Università di Pavia, Via Taramelli 12, Pavia, 27100, Italy

5 DISTAV, Università di Genova, Corso Europa 26, Genova, 16132, Italy

6 Department of Preventive Dentistry, Academic Centre for Dentistry Amsterdam (ACTA), Gustav Mahlerlaan 3004, Amsterdam, LA, 1081, The Netherlands

7 Department of Cariology, Institute of Odontology The Sahlgrenska Academy, University of Gothenburg, Box 450, Gothenburg, 405 30, Sweden

8 Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, 39987, Israel

9 Department of Microbial Diseases, UCL Eastman Dental Institute, 256 Gray’s Inn Road, London, WC1X 8LD, UK

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BMC Complementary and Alternative Medicine 2013, 13:117  doi:10.1186/1472-6882-13-117

Published: 29 May 2013

Abstract

Background

Dental caries is an infectious disease which results from the acidic demineralisation of the tooth enamel and dentine as a consequence of the dental plaque (a microbial biofilm) accumulation. Research showed that several foods contain some components with antibacterial and antiplaque activity. Previous studies indicated antimicrobial and antiplaque activities in a low-molecular-mass (LMM) fraction of extracts from either an edible mushroom (Lentinus edodes) or from Italian red chicory (Cichorium intybus).

Methods

We have evaluated the antimicrobial mode of action of these fractions on Streptococcus mutans, the etiological agent of human dental caries. The effects on shape, macromolecular syntheses and cell proteome were analysed.

Results

The best antimicrobial activity has been displayed by the LMM mushroom extract with a bacteriostatic effect. At the MIC of both extracts DNA synthesis was the main macromolecular synthesis inhibited, RNA synthesis was less inhibited than that of DNA and protein synthesis was inhibited only by roughly 50%. The partial inhibition of protein synthesis is compatible with the observed significant increase in cell mass. The increase in these parameters is linked to the morphological alteration with transition from cocci of the untreated control to elongated cells. Interestingly, these modifications were also observed at sub-MIC concentrations. Finally, membrane and cytosol proteome analysis was conducted under LMM mushroom extract treatment in comparison with untreated S. mutans cells. Significant changes were observed for 31 membrane proteins and 20 of the cytosol fractions. The possible role of the changed proteins is discussed.

Conclusions

This report has shown an antibiotic-like mode of action of mushroom and chicory extracts as demonstrated by induced morphogenetic effects and inhibition of specific macromolecular synthesis. This feature as well as the safe use of this extract as result of its natural origin render the LMM both mushroom and chicory extracts suitable for the formulation into products for daily oral hygiene such as mouthwashes or toothpastes.

Keywords:
Streptococcus mutans; Dental caries; Anticaries compounds; Food components