Possible Mechanisms Of Action And Inhibition Of Biofilm By Cassia Spectabilis (DC.) Methanol Leaf Extract On Candida Albicans Cells And The Cytotoxicity Effect
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Date
2012-07
Authors
Ayah Torey, Angeline Torey
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Candida albicans in its biofilm mode of growth is increasingly attracting interest in
its role in human infections due to the development of resistance to commonly-used
antibiotics or phenotypic adaptation within the biofilm. Hence, in this study the
inhibitory effect of methanol extract of Cassia spectabilis leaves was evaluated
against biofilm-forming C. albicans with the mechanisms of action. The leaf extract
was first standardized in terms of authenticity, assay and chemical constituent
analysis. Then the antifungal activity of the extract against C. albicans was
established by using the disk diffusion and minimum inhibitory concentration (MIC)
assay using the broth macrodilution method. It was found that the MIC value
obtained was 6.25 mg/ml and this concentration of the extract was used throughout
this study. The antibiofilm activity of the extract on C. albicans biofilms formed on
microtitre plate surfaces were evaluated using the XTT (2,3-bis(2-methoxy-4-nitro-5-
sulfophenyl)-5[(phenylamino)carbonyl]-2H-tetrazolium hydroxide) assay and the
extract inhibited 96.88 + 0.35% of the C. albicans biofilm, whereby fluconazole,
which was used as a positive control inhibited of 95.39 + 0.23% of the biofilm.
Visual observations using scanning electron microscopy (SEM) revealed damaged
and abnormal C. albicans cells and the biofilm was shrivelled and broken down
when the fungal cells were treated with the C. spectabilis leaf extract and the extent
of the damage increased as the time of treatment increased. The fluorescent
microscopy results was in agreement with the SEM observation, as well as the
biofilm assay, whereby as the time of treatment with the extract increased, there were
more dead cells which fluoresced red. In addition to the antifungal and antibiofilm
activities, the possible mechanisms of action of the C. spectabilis leaf extract was
determined, whereby four different methods were used.
Description
Keywords
Candida albicans in its biofilm mode of growth , interest in its role in human infections