Chemical composition and antifungal activity of essential oils from Ocimum species

With the increase of microbial diseases and many reports of resistance of microorganisms to antifungal drugs, the importance of studies on bioprospecting of natural products with antimicrobial properties also increases. The aim of this study was to find new antifungal agents among essential oils from five Brazilian Ocimum species: Ocimum americanum, Ocimum basilicum var. purpurascens, O. basilicum var. minimum, Ocimum micranthum and Ocimum selloi. Plant leaves were steam distilled and the obtained essential oils composition was determined by means of GC-MS analysis. The main constituents for O. americanum oil were 1,8-cineole (25.9%) and (Z)-methyl cinnamate (29.4%), for O. basilicum var. purpurascens linalool (41.5%) and α-muurulol (11.8%), for O. basilicum var. minimum linalool (44%) and 1,8-cineole (15.5%), for O. micranthum and eugenol (64.11%) and β-caryophyllene (14.3%) and for O. selloi, linalool (16.8%) and anethole (52.2%). The antifungal activity of essential oils was evaluated against Candida albicans, Candida tropicalis, Candida parapsilosis, Candida glabrata and Candida krusei by the broth microdilution method. Among the five plants O. micranthum and O. selloi showed the best results, with MIC ranging from 312.5 to 1250 μg mL−1. The Ocimum essential oils, mainly O. micranthum and O. selloi are active in vitro against the Candida species showing to be promising sources for new phytotherapeutic agents to treat mycosis due to the presence of effective antifungal compounds as eugenol and anethole.