Chemical characterization of the essential oil of Thymus vulgaris and evaluation of its antifungal activity on the apple scab pathogen (Venturia inaequalis L)

Abstract

This study aims to investigate the chemical composition of essential oils (EO) extracted from the aerial part of Thymus vulgaris L. and to evaluate its antifungal activity against the apple scab pathogen (Venturia ineaqualis L). Chemical analysis of this EO revealed the presence of 30 compounds which represent for approximately 99.07 % of the total component. Linalool, is the most abundant constituent (36.41%), followed by Terpinen-4-ol (10.51%) and β-myrcene (7.5%). Other constituents were identified in varying amounts include para-Cymene (6.6 %); γ-Terpinene (6.11 %), and Carvacrol (0.75 %), with entirely absent of thymol compound. The evaluation of antifungal activity of thyme EO on the growth of Venturia ineaqualis mycelium was marked by a decrease in number of fungal filaments in the colony which was significantly influenced by increasing the doses. The EO concentration that had the minimal inhibitory effect was 300l/ml. Thymus vulgaris EO had a complete inhibitory effect on fungal growth at a dose of 600 l/ml, where no growth was observed. Despite the absence of thymol and the relatively low content of carvacrol, both of which are known to be highly toxic, thyme EO from the Seraidi region was very effective and revealed a very powerful activity against V.ineaqualis, which is likely due to the presence of high levels of monoterpenes (36.96%) and oxygenated monoterpenes (55.51%) associated with other synergistic components.