Compositional Variation in Volatile Constituents and Some Activities of Thyme Essential Oils Harvested from Saudi Arabia

This study evaluates variations in the yield, chemical composition and biological effects of hydro-distilled thyme essential oils (TEOs) linked to variable agro-climatic conditions of fourharvesting regions. The antioxidant activity of TEOs was evaluated by measuring total phenolics content using Folin Ciocalteu reagent based colorimetric assay and DPPH radical scavenging capacity. TEOs along with principal component (durenol) were also evaluated for antimicrobial activity against selected strains of bacteria and fungus by disc diffusion method. The tested TEOs were evaluated for thrombolytic potential based on the clot lysis measurement using streptokinase as standard. The cytotoxicity of TEOs was identified against human RBCs using Triton X-100 and phosphate buffer saline as positive and negative control by taking absorbance at 576 nm. GC-Ms analysis of the tested TEOs was investigated to detect phytochemical components in oil fraction with potent biological activities. Overall, 40 chemical components, representing 98.17-99.56% of oil, were detected by GC-MS/GC-FID analysis with durenol (41.21%) as a principal component. TEOs exhibited good DPPH radical scavenging activity (68.80-94.00%) along with considerable antibacterial, antifungal and sizable thrombolytic activity (clot lysis 4.20-72.60%) with slight cytotoxicity (0.42-530%). TEOs contained oxygenated monoterpenes as a major class while durenol was found as the main component with its highest amount in Abha ecotype. The tested thyme chemotype can be explored as a good source for durenol rich essential oils with valuable antioxidant and antimicrobial properties having promising nutraceutical application with appreciable thrombolytic activity and negligible cytotoxicity.