Determination of essential oil composition by GC-MS and integral antioxidant capacity using photochemiluminescence assay of two Thymus leaves: Thymus syriacus and Thymus cilicicus from different Syrian locations
The Syrian Thymus cilicicus (Th. cilicicus) Boiss & Bal. and Thymus syriacus (Th. syriacus) Boiss chemical components were identified using GC-MS spectrometry. Sixteen constituents representing an average of 93.85% of the essential oil from Syrian Thymus cilicicus were characterized. The major average components in four collection rounds of Thymus cilicicus around the year were: thymol, carvacrol, γ-terpinene, carvyl acetate, dihydrocarvone and anis aldehyde. Eighteen components representing an average of 93.46% of the essential oil of Thymus syriacus were characterized. The major average components in four collection rounds of Thymus syriacus around the year were: carvacrol, dihydrocarvone, β-caryophyllene, p-cymene, farnesol, limonine, menthol, myrecene, γ-terpinene, terpinene- 4-ol and thymol. The integral antioxidant capacity of aqueous and essential oils extracts of both Thymus species: Th. syriacus and Th. cilicicus have been determined by means of a photochemiluminescence assay (PCL). The highest integral antioxidant capacity has been found for Th. syriacus and Th. cilicicus in Fahel mountain and Salah Aldin locations which have a value of total nmol equivalent per gram of dry material at 374.6 ± 0.94 and 475.80 ± 1.20 nmol TE/g DM, respectively.