Activity of Curcuma longa L. Tincture against Biofilms of Candida Standard Strains

Abstract

Aims: To evaluate the fungistatic, fungicidal, and antibiofilm activity of C. longa L. tincture against Candida species. Study Design: Quantitative and mechanistic experimental design using dilution methods to determine the Minimum Inhibitory Concentration (MIC) and the Minimum Candidacidal Concentration (MCC), and specific assays for evaluating the inhibition of biofilm formation and the viability of biofilm-associated cells. Place and Duration of Study: The microorganisms were maintained at the Laboratory of Microbiological Analysis in Health and Environment of the Institute of Tropical Pathology and Public Health at the Federal University of Goiás. The microbiological assays were conducted at the Bioassay Laboratory of the Center for Research and Graduate Studies at the State University of Goiás, and the phytochemical characterization analyses were performed at the Bioproducts and Synthesis Research Laboratory of the State University of Goiás, Anápolis-GO, Brazil, between August 2024 and September 2025. Methodology: The extract was characterized for its curcuminoid profile by HPLC-DAD, and its concentration was determined by rotary evaporation and lyophilization. The MIC and MCC were determined by the broth microdilution method. The action on biofilms was investigated by determining the MBIC50 (concentration that inhibits 50% of the biofilm biomass). Additionally, the viability of yeasts in the biofilm was quantified by CFU counting. Results: We verified that all yeasts form biofilms and that the C. longa L. tincture showed fungistatic activity starting at 45.36 mg∙mL-1 and was fungicidal between 90.72 and 362.88 mg∙mL-1. The tincture reduced biofilm formation variably in the tested yeasts and in a dose-dependent manner with inhibitory concentrations starting at 1.77 mg∙mL-1. Conclusion: The Curcuma longa L. tincture is a promising herbal medicine, being notably more effective at preventing Candida biofilm formation than at eliminating yeasts in suspension, with its superior action attributed to the synergy among its compounds.