The volatile oil of the Lebanese Za'atar ( Origanum syriacum L.) was characterized for its thymol and carvacrol content using gas-liquid chromatography. These two compounds constituted the major components of the oil and were present in equal proportions of 30% in the volatile oil extracted from the leaves and shoot tips of the Origanum plant during the preflowering stage. The percentage of carvacrol in the essential oil increased to 62% after flowering and maturation, while the concentration of thymol decreased to 14%. Origanum oil extracted from plants collected during midseason was evaluated for its antifungal activity against Aspergillus niger , Fusarium oxysporum , and Penicillium species. The oil exhibited strong inhibitory action against the three fungi tested. The minimum inhibitory concentration (MIC) of the oil was found to be 0.1 μl/ml of yeast extract sucrose broth for the fungi tested.
Keywords: Essential oil; Za'atar; antifungal activity.