Antifungal Activity of Capric Acid Against Candida albicans in vitro

Objectives: The objective of this study was to test the susceptibility of Candida albicans to various concentrations of capric acid by determining the minimum inhibitory concentration (MIC), the minimum fungicidal concentration (MFC), and completing a time kill assay.
Methods: C. albicans (ATCC: 321128, 90028, MYA 274, and MYA 2876) were seeded onto Sabouraud Dextrose Agar (SDA) at 37°C in 5% CO₂ for 24h. The MIC (n=9) was determined using an inoculum of 1-5x10³ CFU/mL C. albicans grown in RPMI-1640. Serial dilutions of capric acid (1mM-100mM) with C. albicans strains were placed in 96-well plates and incubated at 37°C in 5% CO₂ for 24h. Fluconazole and solutions with 1% ethanol served as the positive and vehicle controls respectively. The MFC was determined by subculturing 10μl of each well with concentrations at or above MIC on SDA at 37°C in 5% CO₂ for 24h. For the time kill assay, 360μl of 321128 inoculum of 1-5x10³ CFU/mL was added to individual wells on a 24-well plate. 40μl of the initial MFC and a concentration 2x MFC for capric acid (10mM and 20mM), and fluconazole (100μM and 200μM), and vehicle were placed in individual wells. A negative control was included. At specific times (0, 30min, 1h, 2h, 4h, 8h, 24h) 10μl each well was subcultured onto Blood Agar (BA) at 37°C in 5% CO₂ for 24-48h.
Results:
Susceptibility of capric acid against C. albicans showed antifungal activity. The MIC and MFC for each strain were as follows: 321128 (MIC:10-25mM, MFC:10mM); 90028 (MIC:50-100mM, MFC:100mM); MYA 274 (MIC:25-100mM, MFC:25mM); MYA 2876 (MIC:50-100mM, MFC:50mM). The time kill assay showed a reduction of growth for C. albicans 321128 on the 20mM and10mM of capric acid after 4h.
Conclusions: Capric acid had inhibitory effects on fungal growth and this data suggests that capric acid may be a potential antifungal agent against C. albicans.