13th Conference on Medicinal and Aromatic Plants of Southeast European Countries (CMAPSEEC 2026)

Naturally occurring phytochemicals are increasingly investigated as bioactive candidates for antifungal applications. Gallic acid and curcumin possess broad biological activities; however, comparative information on their concentration- and time-dependent anticandidal effects remains limited. This study comparatively evaluated the in vitro activity of standard gallic acid and curcumin against Candida albicans, Candida glabrata, and Candida krusei using minimum inhibitory concentration (MIC) and time-kill kinetic analyses. Gallic acid exhibited an MIC of 200 µg/mL against all three species, whereas curcumin showed an MIC of 400 µg/mL. Time-kill kinetics were evaluated at 100, 200, and 400 µg/mL over 0–24 h. Both compounds showed concentration- and time-dependent reductions in viable populations, with the greatest effects at 400 µg/mL. At 24 h, gallic acid resulted in viable counts of 4.09, 4.19, and 4.22 log₁₀ CFU/mL for C. albicans, C. glabrata, and C. krusei, respectively, compared with 3.93, 3.97, and 4.01 log₁₀ CFU/mL for curcumin. Between 12 and 24 h, gallic acid reduced viable counts by 44.4–55.5% (0.26–0.35 log₁₀), while curcumin produced more consistent reductions of 64.7–66.1% (0.45–0.47 log₁₀). At 400 µg/mL, 24-h viable counts with curcumin were 29.5–39.6% lower than those with gallic acid. EC50 values for curcumin were 194.7, 224.6, and 281.5 µg/mL against C. albicans, C. glabrata, and C. krusei, respectively. For gallic acid, the EC50 was 326.3 µg/mL for C. albicans and >400 µg/mL for the other species. Gallic acid demonstrated greater MIC-based inhibitory potency, whereas curcumin showed stronger and more consistent suppression during prolonged exposure, supporting further investigation of both phytochemicals as anticandidal candidates.