Correlation between chemical composition and antifungal activity of the essential oils of eight Cinnamomum species

Fourteen essential oils hydrodistilled from eight Cinnamomum (Lauraceae) species (C. pubescens Kochummen, C. impressicostatum Kosterm, C. microphyllum Ridl., C. scortechinii Gamb., C. rhyncophyllum Miq., C. cordatum Kosterm, C. zeylanicum Blume, and C. mollissimum Hook f.) were examined for their antifungal activity against six dermatophytes (Trichophyton rubrum, T. mentagrophytes, T. tonsurans, Microsporum canis, M. gypseum, and M. audouini), one filamentous fungi (Aspergillus fumigatus), and five strains of yeasts (Candida albicans, C. glabrata, C. tropicalis, C. parapsilosis, and Crytococcus neoformans) by using the broth microdilution method. The antifungal activities of 13 standard compounds that are prevalent constituents in Cinnamomum oils were also investigated in an effort to correlate the effectiveness of the oils with those of the components of the oils. The chemical composition of the oils was analyzed by GC and GC-MS. Most of the oils showed moderate to strong activity against the fungi. Among the oils, the leaf and bark oils of C. zeylanicum showed the highest activity against all the fungi with MIC values of 0.04 to 0.63 mu g mu L-1. Other oils that gave a strong inhibition on fungal growth were the leaf oil of C. cordatum and bark and twig oils of C. pubescens and C. impressicostatum. Cinnamaldehyde, which was the most abundant component of the bark oil of C. zeylanicum, showed the strongest activity against all the fungi studied. Based on the results of the assay on standard samples, it may be that the high levels of cinnamaldehyde, eugenol, geraniol, benzyl benzoate, and methyl cinnamate in the oils and in combination with the minor components is responsible for the high antifungal activity of the oils.