Antifungal activity of usnic acid and alizarin against Paracoccidioides brasiliensis yeasts

• Grant number: 25/23847-6
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: November 01, 2025
• End date: October 31, 2026
• Field of knowledge: Biological Sciences - Microbiology - Applied Microbiology
• Principal Investigator: Flávio Vieira Loures
• Grantee: Diego Vinícius Alves da Silva
• Host Institution: Instituto de Ciência e Tecnologia (ICT). Universidade Federal de São Paulo (UNIFESP). Campus São José dos Campos. São José dos Campos , SP, Brazil
• Associated research grant: 25/13771-2 - Antifungal potential of usnic acid and alizarin against Paracoccidioides brasiliensis yeasts., AP.R

Abstract

Paracoccidioidomycosis (PCM) is a systemic mycosis endemic to South America, particularly in Brazil. Current antifungal treatments, such as amphotericin B and itraconazole, have important limitations, including prolonged treatment duration and significant adverse effects. Amphotericin B, in particular, is associated with renal, hepatic, and hematological toxicities, which can compromise patient adherence and recovery.In this context, natural compounds such as alizarin and usnic acid have emerged as promising therapeutic alternatives, having demonstrated antimicrobial activity against a variety of fungi, including Candida spp., Cryptococcus spp., Aspergillus spp., Malassezia furfur, Microsporum gypseum, and Trichophyton mentagrophytes. Usnic acid, a dibenzofuran derivative found in lichens of the genus Usnea, and alizarin, an anthraquinone extracted from plants, also exhibit antioxidant, antileukemic, and antiviral properties.This project aims to characterize the antifungal potential of these compounds against Paracoccidioides brasiliensis through in vitro assays to assess fungistatic and fungicidal activity using optical density measurements, flow cytometry, and colony-forming unit (CFU) counts. If found effective, the compounds will be evaluated in a murine model of PCM, with histological analysis and CFU quantification in target organs from treated and untreated mice.Preliminary results indicate a significant reduction in fungal colonies after 24 hours of treatment with both compounds, showing performance comparable to amphotericin B, thereby supporting the continuation of this study.