Composition and microbial activity of thyme (Thymus algeriensis genuinus) essential oil

Abstract

In this study, the essential oil composition of Thymus algeriensis genuinus from Algeria was characterised by gas chromatography with flame ionization detector (GC/FID) and confirmed by gas chromatography coupled to mass spectrometry (GC/MS). The combination of GC/FID and GC/MS has resulted in the identification of 48 compounds then classified into four classes: monoterpene hydrocarbons, oxygenated monoterpenes, sesquiterpene hydrocarbons and oxygenated sesquiterpenes. The essential oil obtained by hydrodistillation is characterized by a rich content of phenolic compounds such as thymol (71%) and carvacrol (4%) versus a minor presence of monoterperne hydrocarbons like p-cymene (3%) and γ-terpinene (0.5%). Furthermore, extraction kinetic study has revealed the effect of conservation period on oil yield and extraction rate especially during the first thirty minutes. As a consequence, we would argue that high moisture content in fresh plant material would produce a high oil yield in a reduced processing time and that reduced conservation period would prevent loss of volatiles before processing. Finally, the antimicrobial and antifungal activities were evaluated using the disc diffusion method. The extracted essential oil has presented a high inhibiting activity against eight bacterial strains up to 75 mm and two species of fungus up to 45 mm.