Comparative antifungal efficacy of trans-cinnamaldehyde and nystatin against biofilm-forming Candida Species: Structural insights and drug susceptibility

Abstract

Biofilm-associated infections caused by Candida species present significant therapeutic challenges due to their resistance to conventional antifungal agents. This study compared the antifungal efficacy of trans-Cinnamaldehyde-a natural compound extracted and purified from Cinnamon Tra My (Vietnam)-with nystatin against Candida albicans, C. glabrata, and C. tropicalis in both planktonic and biofilm forms. Planktonic Minimum Inhibitory Concentration (PMIC) and Minimum Biofilm Inhibitory Concentration (MBIC) values were determined using the CLSI M27-A3 protocol and MTT assay, while biofilm structure was assessed via light microscopy. Nystatin demonstrated superior efficacy across all species, with MBIC₁₀₀ values of 0.008 mg/mL for C. albicans and C. glabrata, and 0.032 mg/mL for C. tropicalis. In contrast, trans-Cinnamaldehyde required 0.32 mg/mL to achieve MBIC₁₀₀ in C. albicans and C. glabrata, and 0.63 mg/mL in C. tropicalis. Microscopic analysis confirmed pronounced biofilm disruption in C. albicans post-treatment with trans-Cinnamaldehyde, whereas C. tropicalis biofilms remained structurally resilient. These findings highlight the species-dependent susceptibility of Candida biofilms and underscore nystatin's continued role as a frontline antifungal. Trans-Cinnamaldehyde, while less potent, shows promise as a natural adjunct, particularly against C. albicans and C. glabrata biofilms.

Keywords: Antifungal resistance; Biofilm susceptibility; Candida biofilm; MBIC; Nystatin; PMIC; Structural analysis; trans-Cinnamaldehyde.