Targeting Biofilm Formation in Candida albicans with Halogenated Pyrrolopyrimidine Derivatives

Abstract

Growing concern over environmental contaminants, including pharmaceuticals and antifungal agents, highlights their role in promoting resistance and biofilm formation by microorganisms. Antifungal resistance, especially in drug-resistant Candida spp., poses a global threat, worsened by the widespread use of antifungal agents in both clinical applications and environmental contamination. This study investigates the antibiofilm properties of various halogenated pyrrolo pyrimidine derivatives, specifically 4-chloro-5-iodo-7H-pyrrolo[2,3-d]pyrimidine (10) and 2,4-dichloro-5-iodo-7H-pyrrolo[2,3-d]pyrimidine (16), against fluconazole-resistant C. albicans. Both compounds demonstrated strong biofilm inhibition, with 16 showing greater efficacy even at lower concentrations. qRT-PCR analysis revealed downregulation of key biofilm- and hyphae/germ tube-relating genes, including ALS3, HWP1, and ECE1, alongside upregulation of stress response and biofilm regulator genes such as CDR11, GST3, IFD6, UCF1, YWP1, and ZAP1, indicating complex regulatory responses to the treatments. Molecular docking analysis revealed that these compounds bind effectively to the binding cavity of the ALS3 protein, with halogen atoms playing a key role in stabilizing interaction. Compound 16 exhibited minimal cytotoxicity in Brassica rapa and Caenorhabditis elegans models, suggesting a favorable ADMET safety profile. Confocal microscopy analysis confirmed the compounds effectiveness in preventing biofilm formation when applied as biodegradable PLGA coatings on biomaterial surfaces. These findings suggest that 16 holds promise as a potent antifungal agent with reduced environmental impact, offering both efficacy and sustainability.