Journal of Ethnopharmacology 140 (2012) 416–423 Contents lists available at SciVerse ScienceDirect Journal of Ethnopharmacology jo ur nal homep age : www.elsevier.com/locate/jethpharm Biofilm inhibition by Cymbopogon citratus and Syzygium aromaticum essential oils in the strains of Candida albicans Mohd Sajjad Ahmad Khan, Iqbal Ahmad ∗ Department of Agricultural Microbiology, Aligarh Muslim University, Aligarh 202002, India a r t i c l e i n f o Article history: Received 4 November 2011 Accepted 11 January 2012 Available online 2 February 2012 Keywords: Cymbopogon citratus Syzygium aromaticum Candida albicans Biofilm Scanning electron microscopy a b s t r a c t 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 of these oils as new anti-biofilm products to deal with the problem of drug-resistance and recurrent infection associated with biofilm mode of growth of Candida spp. © 2012 Elsevier Ireland Ltd. All rights reserved. 1. Introduction In recent times, there has been renewed interest on plants as sources of antimicrobial agents due to their ethnomedicinal uses and the fact that a good portion of the world’s population, par- ticularly in developing countries, rely on plants for the treatment of infectious and non-infectious diseases. The plant-derived drugs have been reported to be safe and without side-effects and antimi- crobial properties of plant volatile oils have been recognized since antiquity (Cowan, 1999). In particular, oils of Cymbopogon citra- tus (lemongrass) and Syzygium aromaticum (clove) have long been used in traditional practices by many ancient cultures. In Ayurveda, the traditional system of healing in India, lemongrass oil is used to treat hypertension, fever, stomach disorders, and to reduce pain ∗ Corresponding author at: Department of Agricultural Microbiology, Faculty of Agricultural Sciences, Aligarh Muslim University, Aligarh 202002, India. Tel.: +91 9456465852. E-mail address: ahmadiqbal8@yahoo.co.in (I. Ahmad). and inflammation associated with rheumatism, cold and flu, and bacterial and fungal infections of throat, urinary and vaginal tract (Carlini et al., 1986; Husain et al., 1988; Schwiertz et al., 2006). Similarly clove oil has been used in toothache and as a carminative, anaesthetic, and as an antimicrobial for oral and skin infections (Cai and Wu, 1996; Ghelardini et al., 2001; Karmakar et al., 2011). Studies have reported the presence of citral, geraniol and myrcene as major active constituents in lemongrass oil (Tyagi and Malik, 2010; Khan and Ahmad, 2011) whereas eugenol predominates in clove oil (Khan et al., 2009). These essential oils have been recom- mended as home remedies for treatment of oral and vaginal fungal infections by numerous books and articles and products contain- ing these essential oils for treatment of such infections are being used in many parts of the world (Barnes, 1989; Newall et al., 1996). Scientific literature has also shown that these oils and its active con- stituents (citral, geraniol and eugenol) possess antifungal activities (Hammer et al., 1999; Dutta et al., 2007; Khan and Ahmad, 2012). A range of mucosal to systemic fungal infections have been reported to be caused by opportunistic pathogen Candida spp. such as oral candidiasis, vaginitis and candidemia. Vulvovaginal 0378-8741/$ – see front matter © 2012 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.jep.2012.01.045