Chemical composition and in vitro antibacterial activity of the pure essential oils and essential oils extracted from their corresponding hydrolats from different wild varieties of Moroccan thyme

This work was designed to study the chemical composition and antibacterial activity, against four bacterial strains including two Gram-negative and two Gram-positive of pure essential oils, and those extracted from corresponding hydrolats of three species of Moroccan Thymus: (Thymbra capitata, Thymus munbyanus and Thymus glandulosus). Analysis of these oils by GS/MS, revealed that the pure essential oil of Thymbra capitata (carvacrol chemotype) is dominated by carvacrol (85, 35%) and the essential oil extracted from its hydrolat (carvacrol /4- tert-butylcatechol chemotype) consists predominantly of carvacrol (75.14%), 4-tert-butylcatechol (14.72%) and thymol (4.36%). Thus, the pure essential oil of Thymus munbyannus (carvacrol/pcymene/ γ−terpinene chemotype) consists mainly of carvacrol (44.52%), p-cymene (16.64%) and γ−terpinene (10.85%), while the essential oil extracted from its hydrolat (carvacrol/thymoquinone/borneol/linalyl anthranilate chemotype) consists especially of carvacrol (36.94%), thymoquinone (10.79%), borneol (10.21%) and linalyl anthranilate (15.78%). The chemical composition of pure essential oil of Thymus glandulosus (thymol/carvacrol/ p-cymene chemotype) shows that this latter consists mainly of monoterpenes especially both phenolic compounds thymol (28.51%) and carvacrol (24.88%) along with their precursors p -cymene (18.57%) and γ−terpinene (10.51%), while the essential oil extracted from its hydrolat (carvacrol/thymol chemotype) consists mainly of carvacrol (45.95%), thymol (44.68%) and 4- tert-butylcatechol (3.87%). These oils showed significant antibacterial activities against the bacterial strains tested.