Comparison of Ferrous Ion Chelating, Free Radical Scavenging and Anti Tyrosinase Properties of Thymus Daenensis Essential Oil with Commercial Thyme Oil and Thymol

Utilization of plants as antioxidants in food processing has a potential for substitution of synthetic antioxidants. In the present work, some unexplored biological activities of Thymus daenensis, commercial thyme essential oils and thymol were comparatively studied.

Ferrous ion chelating was assessed by spectrophotometry by mixing the essential oils with diluted FeSO4 followed by addition of ferrozine. Antioxidative properties were assessed by beta carotene bleaching and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging tests. Gallic acid equivalent of ferric reduction was carried out using FeCl3. Super oxide anion radical scavenging was determined using xanthine oxidase and anti tyrosinase inhibitory activity was determined by a spectrophotometry method using a modified dopachrome method with L-DOPA as the substrate.

Chelating reaction of T. daenensis oil was dose dependent, and its super oxide anion radical scavenging property was higher than the commercial oil. Lipid peroxidation inhibition by T. daenensis oil was stronger and those of the commercial oil and thymol were approximately equal. DPPH free radical scavenging property of T. daenensis oil was higher than trolox, butylated hydroxytoluene and anisol (BHT and BHA). Ferric-reducing antioxidant power (FRAP) of T. daenensis oil was greater. The total phenolics anti tyrosinase IC50 were also determined.

The results point to the nutritional value of these plants in preventing formation of toxic reactive oxygen species, and show that Thymus daenensis, as a good antioxidant, can directly scavenge free radicals. The results from biological properties of Thymus daenensis are indicative of its potentials for use in food and drug industries.