Anticandidal activity of Cassia fistula and its effect on ergosterol biosynthesis

Cassia fistula Linn. (Caesalpiniaceae) has been used in folk medicine. Anthraquinone derivative rhein having antimicrobial properties is actively present in C. fistula fruit. Although, as yet there has been no study of its anticandidal potential.

The present study was conducted to determine the phytochemical composition of fruit pulp and seed extract and their effect on Candida albicans ATCC 10261, Candida glabrata ATCC 90030 and Candida tropicalis ATCC 750, respectively.

The fruit pulp and seed extracts were tested for phytochemicals by various standard methods and rhein was identified by thin-layer chromatography. The anticandidal activity was determined by minimum inhibitory concentration (MIC), growth curve studies, cytotoxicity and ergosterol estimation assay.

The fruit pulp and seed extracts showed high content of phenolic compounds. Rhein was identified in both extracts, Rf 0.38. MICs of seed extract obtained with C. albicans, C. tropicalis and C. glabrata is 350, 300 and 300 μg/ml. However, for fruit pulp extract, these values significantly reduced to 150, 250 and 100 μg/ml, respectively. Comparative MIC values for fluconazole were 16, 16 and 04 µg/ml. At MICs, pulp reduced ergosterol content in cell membrane of C. albicans, C. tropicalis and C. glabrata by 54.42, 48.78 and 68.0%, seed extract by 38.11, 47.0 and 45.0%, whereas, fluconazole showed 93.56, 89.21 and 98.0%, respectively.

C. fistula fruit pulp and seed extract possessed anticandidal activity. The result was significantly correlated between the MICs, cytotoxicity and ergosterol inhibition. It was concluded that the crude extract is a promising source for anticandidal compounds.