Discrimination of Thymus, Origanum, Satureja and Thymbra species from the family Labiatae by untargeted metabolomic analysis

Abstract

The term “thyme” does not refer to herbs that belong to a single species. The genera Thymus, Origanum, Satureja and Thymbra of the family Labiatae are traditionally named as thyme and locally known as ‘kekik’. Unlike Turkey, these species are globally called differently. Spices made of Origanum, Thymus and Satureja are called oregano, thyme and savory, respectively. It is often difficult to differentiate them because of their similar smell and appearance. Most commercial products traded as a mixture of those genera and the mixing together of different species may lead to economically motivated adulteration and a product of reduced value. The species were analysed by LC-ESI-QTOF-MS and a comprehensive statistical workflow was designed. The data of methanolic extracts were assessed and an extraction algorithm was employed for the processing of raw data. Five species were discriminated using principal component analysis (PCA) and hierarchical cluster analysis (HCA). The results of PCA and HCA were consistent with each other. Twenty-one metabolites were determined for the discrimination.