Characterization and enhanced antibiofilm activity of Annona muricata extract in combination with fluconazole against Candida albicans

Introduction: Candida albicans biofilm formation is a significant contributor to antifungal resistance, necessitating new treatment strategies. Annona muricata Lin., a traditional herbal remedy, has shown promise in combating microbial infections. The purpose of this study was to assess the antibiofilm activity of the methanol extract of A. muricata leaves alone or with the addition of fluconazole against C. albicans.

Methods: Phytochemicals from the methanol extract were analyzed by LC-MS, the XTT assay was used for metabolic activity, and morphological characteristics were examined using scanning electron microscopy (SEM). Molecular docking screening of identified compounds in A. muricata methanol leaves extract against a Sap3 receptor (PDB: 2H6T) was also performed.

Results: The LC-MS analysis detected 17 possible phytochemicals. The methanol extract showed a dose-dependent inhibition of biofilm formation, with maximum inhibition of ~60% observed at 240 μg/ml, and inhibition by fluconazole increased from 32% to 76% as the concentration increased from 15 to 240 μg/ml. The combination of A. muricata and fluconazole increased the inhibition significantly, from 74% to 78% at 15 μg/ml to 240 μg/mL, respectively. SEM of control and treated C. albicans biofilms showed an altered morphology and loss of cell integrity by the combination, corroborating the findings. Plant phytochemicals also possess high binding affinity (-9.7 to 8.0 kcal/mol, respectively) for the Sap3 enzyme and may therefore have therapeutic potential against C. albicans.

Conclusion: Consequently, the findings indicate that compounds in the A. muricata methanol extract may function in concert with fluconazole at sub-inhibitory concentrations to suppress C. albicans biofilm formation. This finding paves the way for the formulation and development of antifungal treatment regimens that may limit the development of fluconazole resistance employing this plant part.