Antifungal susceptibility and growth inhibitory response of oral Candida species to Brucea javanica Linn. extract

BACKGROUND Candida species have been associated with the emergence of resistant strains towards selected antifungal agents. Plant products have been used traditionally as alternative medicine to ease candidal infections. The present study was undertaken to investigate the antifungal susceptibility patterns and growth inhibiting effect of Brucea javanica seeds extract against Candida species. METHODS A total of seven Candida strains that includes Candida albicans ATCC14053, Candida dubliniensis ATCCMYA-2975, Candida glabrata ATCC90030, Candida krusei ATCC14243, Candida lusitaniae ATCC64125, Candida parapsilosis ATCC22019 and Candida tropicalis ATCC13803 were used in this study. The antifungal activity, minimum inhibitory concentration and minimum fungicidal concentration of B. javanica extract were evaluated. Each strain was cultured in Yeast Peptone Dextrose broth under four different growth environments; (i) in the absence and presence of B. javanica extract at respective concentrations of (ii) 1 mg/ml (iii) 3 mg/ml and (iv) 6 mg/ml. The growth inhibitory responses of the candidal cells were determined based on changes in the specific-growth rates (μ) and doubling time (g). The values in the presence of extract were computed as percentage in the optical density relative to that of the total cells suspension in the absence of extract. RESULTS B. javanica seeds extract exhibited antifungal properties. C. tropicalis showed the highest growth rate; 0.319 ± 0.002 h(-1), while others were in the range of 0.141 ± 0.001 to 0.265 ± 0.005 h(-1). In the presence of extract, the lag and log phases were extended and deviated the μ- and g-values. B. javanica extract had significantly reduced the μ-values of C. dubliniensis, C. krusei and C. parapsilosis at more than 80% (ρ < 0.05), while others were reduced within the range of 2.28% to 57.05%. The g-values of most candidal strains were extended and significantly reduced (ρ < 0.05) in relative to the untreated. The candidal population was reduced from an average of 10 x 106 to 6 x 106 CFU/ml. CONCLUSIONS B. javanica extract exhibited in vitro antifungal activity against seven oral Candida species. The fungistatic and growth inhibiting effects of B. javanica extract have shown that it has potential to be considered as a promising candidate for the development of antifungal agent in oral health products.