Original research article
Anti-acidogenic, anti-biofilm and slow release properties of Dodonaea viscosa var. angustifolia flavone stabilized polymeric nanoparticles

https://doi.org/10.1016/j.archoralbio.2019.104586Get rights and content

Highlights

  • PLGA-PEG/DVA flavone has anti-S. mutans activity.

  • It also inhibited biofilm formation and acid production in S. mutans.

  • Stabilised nanoparticles retained the flavone and released it slowly.

  • The release of flavone was noted at physiological pH and at cariogenic pH.

  • DVA derived flavone has anticariogenic potential.

Abstract

Objective

Dental caries is caused by plaque associated oral bacteria including a pioneer species Streptococcus mutans. It has ability to form biofilm and produce acids in the oral cavity. Many oral hygiene products containing plant derived compounds have been investigated for their anti-S. mutans activity. Dodonaea viscosa var. angustifolia (DVA), has been found to have this property. However, beneficial concentrations are difficult to maintain in the oral cavity due to continual saliva flow which can be overcome using nanotechnology. The aim of this study was to investigate the anti-acidogenic, anti-biofilm and slow release properties of DVA derived flavone stabilized polymeric nanoparticles.

Methods

Crude extract prepared from DVA leaves was fractionated to produce subfractions and the beneficial subfraction (F5.1) was obtained. Polymeric nanoparticles (PLGA-PEG) were prepared, stabilized with the DVA subfraction (F5.1/NPs) and characterized. Anti-S. mutans, anti-acidogenic and antibiofilm properties were determined. The subfraction release profile (substantivity) and cytotoxicity was determined. Results were analyzed using the Wilcoxon sum test (Mann-Whitney).

Results

F5.1/NPs showed anti-S. mutans property (MIC 1.56 mg/ml). Subinhibitory concentrations of these nanoparticles significantly reduced the acid production in S. mutans (p < 0.01) and also reduced the biofilm formation by 92%. The retention and slow release of the beneficial compound was detected up to 12 h, reaching 0.1 mg/ml concentration at pH 7.4 after 4 h and at pH 5.5 after 5 h. IC50 of F5.1/NPs was 62.5 µg/ml.

Conclusion

the DVA flavone containing nanoparticles showed anticariogenic activity with improved substantivity. Therefore, they have potential for use to control dental caries.

Introduction

Dental caries is the most important oral infection and it is prevalent worldwide (Petersen, Bourgeois, Ogawa, Estupinan-Day, & Ndiaye, 2005). It is caused by plaque associated oral bacteria mainly Streptococcus mutans due to its ability to form biofilm and the production of acids in the oral cavity. Many oral hygiene products containing antimicrobial chemicals have been used to control and prevent dental caries. Medicinal plants have also been investigated for their ability to prevent dental caries. Crude extracts of Dodonaea viscosa var. angustifolia (DVA), have been found to have anti- S. mutans property (Naidoo, Patel, Gulube, & Fenyvesi, 2012). A flavone (5,6,8-Trihydroxy-7-methoxy-2-(4-methoxyphenyl)-4H-chromen-4-one) has been identified as the main compound exhibiting anti- S. mutans, anti-biofilm and anti-acidogenic properties (Ngabaza, Moeno, & Patel, 2018). However, beneficial concentrations are difficult to maintain in the oral cavity due to continual saliva flow which can be overcome using nanotechnology.

Nanoparticles have gained importance in many fields such as medicine, biomedical science, drug gene delivery, optics and chemical industry due to their extremely small size and large surface area to volume ratio (Iravani, 2011). Drugs that are used in combination with nanoparticles (NPs) show an increase in solubility and ability to adhere to biological surfaces thereby improving bioavailability and therapeutic activity (Wang, Dave, & Pfeffer, 2004). Controlled release systems also provide the benefits of protection from rapid degradation, targeting delivery, control of the release rate, and prolonged duration of activity by bioactive agents (Wang et al., 2004).

Polymeric nanoparticles (vary in size between 10–1000 nm) prepared from polymers such as Poly lactic-co-glycolic acid polymeric (PLGA) and Polyethylene glycol (PEG) have chemically modifiable surfaces and they are biocompatible, biodegradable, and capable of drug encapsulation and controlled release. In drug delivery, the drug is dissolved, entrapped, encapsulated or attached to the nanoparticle copolymer matrix (Singh & Lillard, 2009). This makes them potential carriers for safe and efficient drug delivery (Gentile, Chiono, Carmsgnola, & Hatton, 2014). The aim of this study was to investigate the anti-cariogenic and slow release properties of Dodonaea viscosa var. angustifolia derived flavone stabilized polymeric nanoparticles.

Section snippets

Plant material and test cultures

The plant was collected from Pypeklipberg Mkhunyane Eco Reserve in Mpumalanga province, South Africa. The plant was positively identified by a Taxonomist from the herbarium at University of The Witwatersrand as Dodonaea viscosa var. angustifolia Benth which belongs to the Sapindaceae family. Voucher specimen number J94882 was deposited at this herbarium (Patel & Coogan, 2008).

Stock cultures of Streptococcus mutans were obtained from the Oral microbiology laboratory. The cultures were obtained

Extraction of DVA flavone

The crude extract of DVA showed 6 fractions. These fractions were eluted based on polarity and they exhibited different colours. The fraction of interest, subfraction 5.1 was purified by several re-runs of column chromatography. The UV–vis absorption spectrum of subfraction 5.1 confirmed that it contained a flavone (Fig. 1) that showed two major peaks observed at 334 nm and 270 nm. These peaks appeared in regions that were cited as identified in literature, where band A is expected in the range

Discussion

A flavone, 5,6,8-Trihydroxy-7-methoxy-2-(4-methoxyphenyl)-4H-chromen-4-one present in DVA is known to have an anticariogenic properties (Ngabaza et al., 2018). However, if it is to be used in the oral cavity, due to the constant flow of saliva, it is difficult to maintain the beneficial concentrations. Therapeutic compounds with good substantivity such as chlorhexidine can provide long lasting effect because it becomes absorbed on to the oral mucosa which is released slowly providing long

Funding

This project was funded by the University of The Witwatersrand and National Research Foundation, South Africa.

Ethical approval

Stock cultures of Streptococcus mutans were obtained from the Oral microbiology laboratory. These cultures were originally obtained under ethical clearance (M10205) granted by The Human Research Ethics Committee, University of The Witwatersrand.

Authors contribution

Mpho Sebelemetja (postgraduate student) performed experiments and analysed the data, Sharon Moeno supervised the chemistry experiments, assisted in the interpretation of results and reviewed the manuscript, Mrudula Patel conceived the idea and designed the research project, supervised the Microbiology experiments and prepared manuscript.

Declaration of Competing Interest

We declare that there is no conflict of interest.

Acknowledgements

We thank National research foundation and Faculty Research Committee, The University of The Witwatersrand for the financial support.

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