Chemical profile and in vitro antibacterial potential of essential oils and hydrolat extracts from aerial parts of three wild species of Moroccan Thymus

Abstract

The present study aims to determine and compare the chemical composition of essential oils (EO) and hydrolat extracts (HE), isolated from three wild varieties of Moroccan thyme (T. satureioides Coss., T. willdenowii Boiss. and T. zygis L.) and to assess their antibacterial activity against four bacterial strains: Gram- (E. coli, Pr. Mirabilis) and Gram+ (B. subtilis, S. aureus). The findings showed that carvacrol (44.95%) and its biogenetic precursor p-cymene (23.36%) were the most dominant compounds of T. zygis L EO. The major volatile compounds in T. willdenowii Boiss EO were found to be thymol (42.38%), carvacrol (16.49%), and p-cymene (13.29%). Thus, T. satureioides Coss EO consists mainly of carvacrol (27.57%) and borneol (21.56%). On the other hand, carvacrol (72.33%) and thymol (10.70%) were the most prominent constituents in T. zygis L HE. T. willdenowii Boiss was dominated by thymol (65.01%) and carvacrol (21.74%). Furthermore, T. satureioides Coss HE was characterized by a high percentage of carvacrol (47.45%), borneol (25.04%), and γ-terpineol (19.34%). All investigated extracts exercised a strong antibacterial power against both tested Gram-positive and Gram-negative strains. However, the weakest activity was observed with T. satureioides Coss. EO and HE. The biological potential of HEs was found much higher than that of the corresponding EOs, which may give hydrolats a great value in aromatherapy to the detriment of essential oils.