Antifungal Evaluation of Capric Acid on Candida species in vitro

Objectives: The nature of oral candidiasis and the increased antifungal resistance demand the search for novel antifungal therapeutic agents. This study tested the susceptibility of 4 species of Candida: C. albicans (ATCC:MYA2876), C. dubliniensis (ATCC:MYA646), C. glabrata (ATCC:MYA275), and C. tropicalis (ATCC:MYA750) to various concentrations of capric acid using minimum inhibitory concentration (MIC), minimum fungicidal concentration (MFC), and time kill assay.
Methods: Candida spp. were streaked onto Blood Agar (BA) at 37°C in 5%CO₂ for 24h. The MIC (n=9) was determined using an inoculum of 1-5x10³ CFU/mL for each candida spp. grown in RPMI-1640. Capric acid dilutions (1mM-100mM) with each candida spp. were placed in 96-well plates and incubated at 37°C in 5%CO₂ for 24h. Fluconazole and 1% ethanol were the positive and vehicle controls, respectively. The MFC was determined by subculturing 20μl of each well with concentrations at or above MIC onto BA at 37°C in 5%CO₂ for 24h. A time kill assay using MYA2876 was performed. 900μl of inoculum at 1-5x10³ CFU/mL was added to individual wells on a 24-well plate containing 100μl of the initial MFC and 2x MFC for capric acid and fluconazole. At specific times (0-1-2-4-8-24h), 50μl of each well was subcultured onto BA at 37°C in 5%CO₂ for 24-48h. A 1:10 dilution of the capric acid and fluconazole concentrations at 8h and 24h were made. 50μl of each dilution was subcultured onto BA.
Results: Susceptibility of capric acid against Candida spp. showed antifungal activity: C. albicans MYA 2876 (MIC: 50-100mM, MFC: 50mM); C. dubliniensis MYA 646 (MIC: 25-100 mM, MFC: 25mM); C. glabrata MYA 275 (MIC: 25-100 mM, MFC: 50 mM); C. tropicalis (MIC: 25-100mM, MFC: 100mM). The time kill assay showed a reduction of growth for C. albicans MYA2876 after 4h.
Conclusions: This data suggests that capric acid may be a potential antifungal agent against Candia spp.