Anti-Candida albicans activity of active substances derived from Morinda citrifolia fruit

Abstract

Morinda citrifolia (Yor in Thai) fruit is a kind of herb used in a traditional Thai medicine recipe. It has been reported to treat bacterial infections and/or fungal diseases, including candidiasis. The antimicrobial activity, especially anti-Candida activity was examined by means of agar well diffusion method and broth microdilution method, using 4 strains of C. albicans (TISTR 5239, TISTR 5779, BCC 6120 and clinical isolate) as indicating strains.  The M. citrifolia fruit from southern region of Thailand was collected and used as source of active substances (AS), classified as 1) AS derived from ripe M. citrifolia fruit 2) AS derived from powder-M. citrifolia fruit extracted with 80% ethanol and 3) AS derived from sheet-M. citrifolia fruit extracted with 80 % ethanol.  It indicated that all types of AS from M. citrifolia fruit at a concentration of 120 or 240 mg/ml could inhibit the growth of C. albicans with an inhibition zone in the range of 14.0 + 0.0 to 20.0 + 0.0 mm and 18.0 + 0.0 to 23.5 + 0.5 mm, respectively when they were tested by agar well diffusion method.  The inhibition zone was appeared as closely as the inhibition zone obtained by antifungal drugs; amphotericin B (10 µg/ml), ketoconazole              (15 µg/ml), nystatin (50 µg/ml) and fluconazole (25 µg/ml). The minimum fungicidal concentration (MFC) against C. albicans obtained in the range of 0.94 to 15.00 mg/ml when tested by the broth microdilution method. Interestingly, it was also found that all types of AS derived from M. citrifolia fruit and amphotericin B showed synergistically effect against C. albicans. It implied that AS derived from M. citrifolia fruit may be efficacially used in combination  with antifungal drug for therapeutic or prophylaxis activity of fungal infections in the clinical trial.