Ethnopharmacological relevance: Oils of Cymbopogon citratus and Syzygium aromaticum have been used in
traditional medicine to treat fungal infections of skin, mouth, urinary and vaginal tract in Asian countries
particularly India and other developing countries.
Aim of the study: To evaluate essential oils of Cymbopogon citratus and Syzygium aromaticum for their
anti-biofilm activity against strong biofilm forming strains of Candida albicans.
Materials and methods: XTT reduction assay, Time kill assays, light microscopy and scanning electron
microscopy (SEM) were employed to determine the effect of test oils on the Candida albicans biofilms.
Results: Most of the Candida albicans strains tested displayed formation of moderate to strong biofilms.
Preformed Candida biofilms showed ≥1024 times increased resistance to antifungal drugs, 2 times to
Syzygium aromaticum, but no increased tolerance for Cymbopogon citratus. Test oils were more active
against preformed biofilms compared to amphotericin B and fluconazole. At 0.5× MIC, Cymbopogon
citratus followed by Syzygium aromaticum were most inhibitory against biofilm formation. Light and
electron microscopic studies revealed the deformity of three dimensional structures of biofilms formed
in the presence of sub-MICs of Cymbopogon citratus. The cell membranes appeared to be the target site
of compounds in sessile cells as displayed by SEM observations.
Conclusion: Our data had demonstrated promising in vitro anti-biofilm activity by Cymbopogon citratus
and Syzygium aromaticum and confirm the ethnopharmacological use of these oils in muco-cutaneous
Candida infections. Furthermore, it suggests exploitation ofthese oils as new anti-biofilm products to deal
with the proble