Bioenhancer potential of Aegle marmelos (L.) Correa essential oil with antifungal drugs and its mode of action against Candida albicans

Efficacy of clinical antibiotics has decreased with increase in drug resistance against fungal pathogens. This work proposes a novel approach to combat fungal infections by combining an-tibiotics with essential oil from the leaves of Aegle marmelos (L.) Correa. GC-MS evaluation de-tected nine compounds with alpha-Phellandrene and D-Limonene as the major phytocompounds. The major phytocompounds were quantified by using standard calibration curve of alpha-Phellandrene and D-Limonene and the amount obtained was 385 +/- 0.096 and 330 +/- 0.100 ppm respectively. Additionally, the anti-candida activity of A. marmelos essential oil (AMEO) was evaluated using the agar well diffusion assay and showed zone of inhibition of 24 +/- 0.5 and 22 +/- 0.30 mm against both the C. albicans strains (ATCC 90028 and MTCC277), respectively. Further, the mini-mum inhibitory concentration (MIC) showed a fungicidal effect against both ATCC90028 and MTCC277 strains of C. albicans and ranged from 0.312 to 0.156% (v/v). The antifungal activity against C. albicans was found to be potent and effective. Synergistic potential was determined us-ing time kill assay and checkerboard method showing increased antifungal efficacy of clinical drugs by 16 and 32 folds, with complete death of cells after 16 h. The assessment of the mode of action of essential oil and antibiotics alone and in combination was done through sorbitol test and Field Emission Scanning Electron Microscopy (FESEM) observations. The sorbitol test demonstrated that the antifungal activities of AMEO, both on their own and in combination with antibiotics, are not associated with the biosynthesis pathways of the cell wall. According to the results of the ergosterol test, AMEO combined with antibiotics appear to bind to the ergosterol in the membrane. This results in an increase in ion permeability, which ultimately leads to cell death. FESEM analysis also confirmed this by showing complete rupture and disruption of the fungal membrane of C. albicans cells treated with essential oil combined with antibiotics. At separate capacity in broth which means when they were used individually, they induced shrinkage and distortion. Thus represents an effective treatment for candidiasis by acting as a refinement in drug design.