Evaluation of antioxidative constituents from thyme

The non-polar fraction of thyme was examined for the occurrence of phenolic components and their antioxidative activity. In addition to carvacrol (II) and thymol (III), p-cymene-2,3-diol (I; 2,3-dihydroxy-4-isopropyl-1-methylbenzene) was isolated for the first time from thyme. The structure of I was elucidated using H-1 nuclear magnetic resonance (NMR), C-13 NMR, and mass spectrometry. Antioxidative activity was investigated with the Rancimat method (100 degrees C) and the Schaal test (60 degrees C). Compound I exhibited the strongest antioxidative activity which was greater than that of alpha-tocopherol and butylated hydroxyanisole. Five thyme species were analysed by means of HPLC with electrochemical detection for the concentration of compounds I-III. The highest amounts of I-III were found in Thymus vulgaris L.