Synergistic potential of Bauhinia holophylla leaf extracts with conventional antifungals in the inhibition of Candida albicans: A new approach for the treatment of oral candidiasis

Abstract

Objective

This study investigated the combination of Bauhinia holophylla (Bong.) Steud. leaf extracts with conventional antifungal agents, highlighting the extracts' potential as adjuvants in treating oral candidiasis.

Design

Ethanolic and aqueous extracts of B. holophylla leaves were analyzed using ultra-high-performance liquid chromatography with a diode array detector (UHPLC-DAD) to assess their chemical composition. Their Minimum Inhibitory Concentration (MIC) against standard strains of Candida albicans and isolates from oral mucosa was determined. Additionally, the potential synergistic effects with chlorhexidine gluconate, nystatin, and fluconazole were investigated, along with their impact on inhibiting and disrupting biofilm formation, germ tube formation of C. albicans, and cytotoxicity in human erythrocytes.

Results

Protocatechuic acid, epicatechin, and rutin were identified in both extracts. They exhibited fungistatic activity with a median minimum inhibitory concentration (MIC₅₀) of 15.62 µg/mL for the ethanolic extract (EEB) and 62.50 µg/mL for the aqueous extract (AEB) against C. albicans. In growth kinetics, both extracts reduced the viable cell count of C. albicans by 2 logs after 24 h compared to the positive control. The extracts reduced germ tube formation by 81.6 % for EEB and 86.3 % for AEB. The synergistic combination with fluconazole and nystatin resulted in a 50 % reduction in the concentration required to inhibit C. albicans growth. No hemolytic activity was detected in human erythrocytes at the tested concentrations.

Conclusion

Both ethanolic and aqueous extracts show promising potential as adjuvants in managing oral candidiasis. Notably, the aqueous extract is advantageous due to its non-toxic solvent, cost-effectiveness, and ease of preparation.