Chemical Composition and Antimicrobial Activity of the Essential Oils Isolated from the Herbage and Aqueous Distillates of twoThymusSpecies

The essential oils are generally extracted from aromatic plants through hydro- or steamdistillation process. During the process of distillation the slightly hydrophilic fraction of the essential oil gets dissolved in the aqueous distillate. This aqueous distillate is generally considered waste hence discarded during the distillation process. The aim of this study was to isolate the water soluble fractions of the essential oils of Thymus serpyllum L. and Thymus linearis (Benth.) grown in India and explore their chemical and antimicrobial potentials. The herbs of T. serpyllum and T. linearis were hydro-cum-steam distilled in a small size field distillation unit. The main essential oils (primary oil) were decanted from the receiver after completion of distillation process, while the aqueous distillates (hydrosols) of both the species were collected in separate containers and used for the isolation of dissolved oils (secondary essential oil). The primary and secondary essential oils were analyzed using GC-FID and GC-MS techniques. The antimicrobial activity of these oils was determined against six pathogenic bacterial and two fungal strains. The secondary essential oils of T. serpyllum and T. linearis were rich in phenolic compounds (92.3% and 96.4%, respectively) as compared to primary essential oils (42.1% and 47.9%, respectively). The bioassay showed that the secondary oils of both the Thymus spp. exhibited stronger antibacterial and antifungal activities than primary oils. Present study concluded that the aqueous distillates of Thymus spp, a byproduct of aromatic distillation, can be used as a potential source of thymol or it can be used as such for different antimicrobial applications.