Composition, Antifungal, Phytotoxic, and Insecticidal Activities of Thymus kotschyanus Essential Oil

Abstract

Essential oils (EOs) are some of the outstanding compounds found in Thymus that can exert antifungal, phytotoxic, and insecticidal activities, which encourage their exploration and potential use for agricultural and food purposes. The essential oils (EO) obtained from Thymus kotschyanus collected in the East Azerbaijan Province (Iran) were characterized using a gas chromatography-mass spectrometry (GC-MS) analysis. Thymol was the most important compound (60.48%), although 35 other active compounds were identified in the EO. Significant amounts of carvacrol (3.08%), p-cymene (5.56%), and γ-terpinene (6.67%) were found in the EO. The T. kotschyanus EO was tested against important phytopathogenic fungi ( Botrytis cinerea, Aspergillus niger, and Penicillium expansum). The antifungal assay showed that the use of ≥500 ppm of EO resulted in a fungicidal effect against all funguses tested. In a similar way, the use of ≥500 ppm of EO inhibited the germination of all crop weed seeds ( Amaranthus retroflexus L. and Panicum miliaceum L.) and their subsequent growth, which demonstrated its herbicidal effect. Finally, the insecticidal capacity of T. kotschyanus EO was also observed against selected insects ( Oryzaephilus surinamensis and Sitophilus oryzae). O. surinamensis was more susceptible to the effect of EO (LC ₅₀ = 4.78 µL/L air) than S. oryzae (LC ₅₀ = 13.20 µL/L air). The obtained results of the present study can provide new safe resources to the development of new products for the food, agriculture, and pharmaceutical industries.