Beetroot Extract Solution as a Photosensitizer for Antimicrobial Photodynamic Therapy- An in Vitro Study

Cinthya Cosme Gutierrez Duran; Ana Paula Taboada Sobral; Amanda Rafaelly Honório Mandetta; Marcela Letícia Leal Gonçalves; Monica Rosas Da Costa Iemma; Eliane  Trovatti; Kristianne Porta Santos Fernandes; Renato Araujo Prates; Raquel Agnelli Mesquita Ferrari; Sandra Kalil Bussadori

doi:10.5455/JPPR.20250820113600

Abstract
Background: The use of natural dyes in antimicrobial photodynamic therapy (aPDT) has gained increasing attention due to their biocompatibility, low toxicity, and potential clinical applicability. However, the photodynamic performance of crude, non-purified plant extracts remains poorly explored. This preclinical study evaluated the physicochemical stability, cytocompatibility, and antimicrobial behavior of beetroot extract as a natural photosensitizer for aPDT. Methods: The extract was assessed through pH monitoring, absorbance analysis, microbiological assays against Candida albicans, and cytotoxicity tests using L929 fibroblast cells, in accordance with ISO 10993-5 standards. Results: The results demonstrated that the beetroot extract maintained pH stability and exhibited acceptable cytocompatibility at the tested concentrations. Although limited absorbance in the visible spectrum was observed, the extract remained chemically stable under irradiation conditions and showed intrinsic antimicrobial activity. Conclusion: These findings provide important preliminary insights into both the potential and limitations of beetroot extract as a photosensitizer for aPDT, supporting future optimization strategies aimed at improving light absorption and antimicrobial efficacy.

Key words: Beetroot Extract, Antimicrobial Photodynamic Therapy, Betalains, Candida Albicans, Cytotoxicity, Photosensitizer.