Preliminary investigation of free radical scavenging activity and total phenolic content of three cultivated Thymus chemotypes from Bulgaria

Abstract

Nikolova, M., Jekova, G., Dzhurmanski, A.: Preliminary investigation of free radical scavenging activity and total phenolic content of three cultivated Thymus chemotypes from Bulgaria , Biologica Nyssana, 3 (1), September 2012: 11-15.

Methanol extracts of three varieties of Thymus “Slava”, “German winter” and “Pagane”, representatives respectively of citral, thymol and geraniol chemotype were evaluated for their antioxidant potential and phenolic content. Total content of phenols was determined by spectrophotometric method using Folin-Ciocalteu reagent. The antioxidant potential of methanol extracts was estimated by 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) free radical assay. All of the examined extracts exhibited significant free radical scavenging activity and their IC50 values were below 50 μg/mL. The highest antioxidant activity was determined for the extract of thymol chemotype “German winter” with IC50 value – 19.34 μg/mL. The extract of this variety had the highest amount of phenols 75.61 mg/g extract. The other two varieties “Slava” and “Pagane” have a lower content of phenols and antiradical activity. Influence of three stages of flower development on antiradical activity and total phenolic content was examined for variety “Pagane”. The highest antioxidant activity was determined on the extract prepared from plant material collected at the stage “end of flowering”. For the first time, provides data on the phenolic content and antiradical activity of varieties “Slava” and “Pagane”. These results are the basis for selection of varieties with high antioxidant potential for the preparation of cosmetic and herbal products.

Key words: Thymus vulgaris, Thymus marschalianus, DPPH, citral, thymol, geraniol