Fruits of Heracleum crenatifolium Boiss., Heracleum sphondylium L. subsp. ternatum (Velen.) Brummitt, and Heracleum platytaenium Boiss. (Umbelliferae) were hydrodistilled to obtain essential oils that were then analyzed by GC and GC/MS. The major component was identified as octyl acetate (93.7, 87.6 and 31.6% respectively). Octyl butyrate was also characterized as the main component in H. platytaenium oil. Furthermore, anticandidal activity of the oils was evaluated using the microdilution broth method. All the oils showed good inhibitory effects against C. glabrata.A rapid increase is observed in the number of Candida infections on people with compromised immune systems such as cancer and AIDS patients. Infections are usually difficult to eradicate completely in patients receiving antifungal agents continuously for long periods of time [1,2]. Anticandidal drugs such as fluconazole have been reported to cause resistance [3].Previously, antifungal resistance used to be rare on Candida species; however, at present resistance is a very serious problem. Furthermore, Candida species other than C. albicans have, in recent years, shown to be responsible for fungemia. C. parapsilosis, C. tropicalis, and C. glabrata infections are more common now than before [4].Since the antimycotic activity of plants remains largely unexplored, interest has grown in the search for anticandidal agents from plants [5]. Our group has previously reported on the occurrence of over 5.000 natural compounds with anticandidal activity [6].Here we report on anticandidal effects of the fruit essential oils of Heracleum crenatifolium Boiss., Heracleum sphondylium L. subsp. ternatum (Velen.) Brummitt, and Heracleum platytaenium Boiss. Heracleum crenatifolium is an endemic plant and this is the first report on its essential oil composition and anticandidal activity. The essential oils were analyzed using both gas chromatography (GC) and gas chromatography/mass spectroscopy (GC/MS) techniques.The composition and relative percentages of individual components of the oil were determined by chromatographic and spectroscopic means. Major components were identified as octyl acetate (93.7, 87.6 and 31.6% respectively) for each essential oil. In the oil of H. platytaenium, octyl butyrate (37.8%) was the main component. Complete GC/MS analysis of the oils will be reported elsewhere [9]. Main components in the oils are shown in Table 2. Results of anticandidal assays are given in Table 3.The essential oils did not show outstanding inhibitory effect. They showed moderate activity (MIC values 0.25 to 1.0 mg/mL) against most Candida species. However, their effect was close to that of the standard antifungal agent ketoconazole on Candida dubliniensis and Candida glabrata. The anticandidal effects were better expressed on C. glabrata.Our group has previously reported on the antimicrobial activity of H. sphondylium subsp. ternatum (collected from another region) essential oil that has 1-octanol (50.3%) as the main component [10]. The oil was shown to inhibit Can...