Photodynamic Therapy With Propolis: Antibacterial Effects on Staphylococcus aureus, Streptococcus mutans and Escherichia coli Analysed by Atomic Force Microscopy

Synthesis and evaluation of antibacterial and antioxidant effects of propolis nanoparticles and cinnamon nanostructures in preventive dentistry: Experimental and theoretical approaches

INTRODUCTION

Natural products such as green propolis and cinnamon have been used traditionally in medicine due to their medicinal value. Recently, interest has grown in developing nanotechnology-based approaches to enhance the biological activity of these compounds.

OBJECTIVE

This study evaluated the antioxidant and antibacterial properties of macro-sized and nanostructured forms of green propolis and cinnamon against Streptococcus mutans (S. mutans) and the 2,2-diphenyl-2-picrylhydrazyl (DPPH) assay.

MATERIAL AND METHODS

The sonochemical method was used to synthesize green propolis nanoparticles (PNPs) and cinnamon nanoparticles (CNPs). Their size was confirmed by scanning electron microscopy (SEM) and dynamic light scattering measurements, while they were compared with propolis (P) and cinnamon (C). The antioxidant activity was measured using the DPPH assay, while the minimum inhibitory concentration (MIC) test determined the antibacterial activity against S. mutans. One-way analysis of variance (ANOVA) and Tukey's post hoc tests (α = 0.05) were conducted to analyze the data. Furthermore, docking calculations were carried out to examine the potential of incorporating any new supplements or therapies into your routine.

RESULTS

The MIC were 5.46, 21.87, 21.87, and 175 g/L for PNPs, P, CNPs, and C groups, respectively. The PNPs exhibited the most significant antibacterial effect while C was weakest. About antioxidant activity, PNPs and P exhibited significant differences from other groups (P = 0.000 and 0.001, respectively), while CNPs and C showed no significant difference between each other (P = 0.07). The docking calculations revealed a strong interaction between both nanoparticles and S. mutans. The binding energy of dihydroflavonols on propolis nanoparticles was -6.83 kcal/mol, indicating a stable connection.

Antimicrobial photodynamic therapy with Brazilian green propolis controls intradermal infection induced by methicillin-resistant Staphylococcus aureus and modulates the inflammatory response in a murine model

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the leading causes of skin and soft tissue infections worldwide. This microorganism has a wide range of antibiotics resistance, a fact that has made the treatment of infections caused by MRSA difficult. In this sense, antimicrobial photodynamic therapy (aPDT) with natural products has emerged as a good alternative in combating infections caused by antibiotic-resistant microorganisms. The objective of the present study was to evaluate the effects of aPDT with Brazilian green propolis against intradermal MRSA infection in a murine model. Initially, 24 Balb/c mice were infected intradermally in the ears with 1.5 × 108 colony-forming units of MRSA 43300. After infection, they were separated into 4 groups (6 animals per group) and treated with the vehicle, only Brazilian green propolis, only blue LED light or with the aPDT protocol (Brazilian green propolis + blue LED light). It was observed in this study that aPDT with Brazilian green propolis reduced the bacterial load at the site of infection. Furthermore, it was able to inhibit weight loss resulting from the infection, as well as modulate the inflammatory response through greater recruitment of polymorphonuclear cells/neutrophils to the infected tissue. Finally, aPDT induced an increase in the cytokines IL-17A and IL-12p70 in the draining retromaxillary lymph node. Thus, aPDT with Brazilian green propolis proved to be effective against intradermal MRSA infection in mice, reducing bacterial load and modulating the immune response in the animals. However, more studies are needed to assess whether such effects are repeated in humans.

Characterization of Brazilian green propolis as a photosensitizer for LED light-induced antimicrobial photodynamic therapy (aPDT) against methicillin-resistant Staphylococcus aureus (MRSA) and Vancomycin-intermediate Staphylococcus aureus (VISA)

Staphylococcus aureus is the primary cause of skin and soft tissue infections. Its significant adaptability and the development of resistance are the main factors linked to its spread and the challenges in its treatment. Antimicrobial photodynamic therapy emerges as a promising alternative. This work aimed to characterize the antimicrobial photodynamic activity of Brazilian green propolis, along with the key bioactive compounds associated with this activity. Initially, a scanning spectrometry was conducted to assess the wavelengths with the potential to activate green propolis. Subsequently, reference strains of methicillin-resistant Staphylococcus aureus (MRSA ATCC 43300) and vancomycin-intermediate Staphylococcus aureus (VISA ATCC 700699) were exposed to varying concentrations of green propolis: 1 µg/mL, 5 µg/mL, 10 µg/mL, 50 µg /mL and 100 µg/mL and were stimulated by blue, green or red LED light. Finally, high-performance liquid chromatography coupled with a diode array detector and tandem mass spectrometry techniques, along with classic molecular networking analysis, was performed to identify potential bioactive molecules with photodynamic activity. Brazilian green propolis exhibits a pronounced absorption peak and heightened photo-responsiveness when exposed to blue light within the range of 400 nm and 450 nm. This characteristic reveals noteworthy significant photodynamic activity against MRSA and VISA at concentrations from 5 µg/mL. Furthermore, the propolis comprises compounds like curcumin and other flavonoids sourced from flavone, which possess the potential for photodynamic activity and other antimicrobial functions. Consequently, Brazilian green propolis holds promise as an excellent bactericidal agent, displaying a synergistic antibacterial property enhanced by light-induced photodynamic effects.