Photodynamic Therapy With Propolis: Antibacterial Effects on and Escherichia coli Analysed by Atomic Force Microscopy.

Journal: Journal of lasers in medical sciences
Published Date: Dec 30, 2020

Abstract

Photodynamic therapy (PDT) is a process that uses a light source (e.g. laser), oxygen molecules and a photosensitizing agent. PDT aims to act against pathogens, including those resistant to antimicrobials. The association of PDT with natural drugs, such as Propolis, has not been widely studied. Therefore, this study aimed to evaluate the antimicrobial effect of PDT in vitro by using Propolis as a photosensitizing agent. For this purpose, the dry Propolis extract was used as a photosensitizer and a low-power laser (Photon Laser III model) was irradiated onto the microwells for 90 seconds. Gram-positive and Gram-negative bacterial strains were used in the tests at a concentration of 5 × 10 CFU/mL. Initially, the antibacterial activity of the photosensitizers without laser action was determined by using a serial microdilution method before the experiment with a laser. After the incubation of the plates in a bacteriological oven, resazurin (0.1%) was added and the minimum inhibitory concentration (MIC) was determined. Alterations in the morphology of the bacteria were analysed by using atomic force microscopy (AFM). Bacteria were sensitive to Propolis with MICs ranging from 13.75 to 0.85 mg/mL, but no susceptibility was observed for methylene blue without laser application. A change was observed for MIC values of Propolis against after irradiation, which decreased from 1.71 mg/mL to 0.85 mg/mL. However, this behaviour was not observed in , the only gram-negative strain used. In addition, AFM images revealed alterations in the size of one of the bacteria tested. The Propolis is more active against gram-positive bacteria and PDT improved its activity against one of the strains tested.

Authors

  • Alice de Morais Veras Fonseca
    Undergraduate Medical Student at the Faculty of Human, Exact and Health Sciences of Piauí of the Institute of Higher Education of Vale do Parnaíba, Parnaíba, PI, Brazil.
  • Guilherme Herbet Leite Sampaio
    Undergraduate Medical Student at the Faculty of Human, Exact and Health Sciences of Piauí of the Institute of Higher Education of Vale do Parnaíba, Parnaíba, PI, Brazil.
  • Wládia Pontes Araujo
    Undergraduate Medical Student at the Faculty of Human, Exact and Health Sciences of Piauí of the Institute of Higher Education of Vale do Parnaíba, Parnaíba, PI, Brazil.
  • Raí Emanuel da Silva
    Biodiversity and Biotechnology Research Center (BIOTEC), Federal University of Piauí. Parnaíba, PI, Brazil.
  • Fábio de Oliveira Silva Ribeiro
    Biodiversity and Biotechnology Research Center (BIOTEC), Federal University of Piauí. Parnaíba, PI, Brazil.
  • Manoel da Paixão Brito
    Biodiversity and Biotechnology Research Center (BIOTEC), Federal University of Piauí. Parnaíba, PI, Brazil.
  • Francisca Beatriz de Melo Sousa
    Biodiversity and Biotechnology Research Center (BIOTEC), Federal University of Piauí. Parnaíba, PI, Brazil.
  • Amanda Azevedo Torres
    Undergraduate Medical Student at the Federal University of Piauí, Parnaíba, PI, Brazil.
  • Alyne Rodrigues Araújo
    Biodiversity and Biotechnology Research Center (BIOTEC), Federal University of Piauí. Parnaíba, PI, Brazil.
  • Antonione Santos Bezerra Pinto
    Medical Professor at the Faculty of Human, Exact and Health Sciences of Piauí of the Institute of Higher Education of Vale do Parnaíba, Parnaíba, PI, Brazil.

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