Composition of Cassia fistula oil and its antifungal activity by disrupting ergosterol biosynthesis

Cassia fistula oil was investigated for antifungal activities against standard and clinical isolates of Candida species. Gas chromatography coupled with mass spectrometric (GC-MS) analysis of C. fistula oil revealed the presence of antimicrobial compounds like β-sitosterol, stigmasterol, ergosterol, betulinic acid, lupeol, fucosterol, α-amyrin and friedelin. The minimum inhibitory concentration (MIC) of the pulp and seed oils ranged between 250-300 and 350-500 μg/mL respectively. Both oils also inhibited by ≥63.8% ergosterol bio-synthesis in Candida cell wall {fluconazole (standard) ≥89.1%)}. The MICs were significantly correlated with the ergosterol content decrease in the cell wall (Student's t test p ≤ 0.005). We can, therefore, conclude that active compounds are present in Cassia fistula oil that primarily target ergosterol biosynthesis in Candida cell wall.