Antifungal effects of ligustilide and butylidene phthalide and its synergism with antibiotics
Ligustilide and butylidene phthalide, the major components of Ligusticum chuanxiong essential oil were isolated from this Umbelliferae and the anti-Trichophyton effects in combination with antifungal drugs were evaluated. Checkerboard microtiter and disk diffusion tests were used to measure combined effects against Trichophyton species, T. erinacei, T. mentagrophytes, T. rubrum, T. schoenleinii, T. tonsurans and T. soudanense. Susceptibility of these Trichophyton species to L. chuanxiong essential oil differed distinctly. The fractional inhibitory concentrations (FICIs) against Trichophyton species ranged between 0.27 and 0.56 for ketoconazole combined with ligustilde or butylidene phthalide, indicating synergism or additive effects between the antibiotic and essential oil compounds. Testing by itraconazole instead of ketoconazole, similar combination effects were observed with FICIs from 0.31 to 0.63 against the tested strains of T. mentagrophytes, T. rubrum, T. schoenleinii, and T. soudanense. Thus, data reported here showed that Trichophyton susceptibility to ketoconazole and itraconazole could be notably improved by ligustilde and butylidene phthalide.
Acknowledgements: This study was supported by a grant from Duksung Women's University (2007).
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