Differentiation of Thymus vulgaris L. sample lots by NMR based metabolic profiling

Thymus vulgaris L. represents one of the major ingredients of herbal medicinal products used for the treatment of bronchitis and cough. Authenticity, yield of desired secondary metabolites, possible adulteration or spoilage of the starting drug material are quality control issues which have to be investigated. NMR based metabolic profiling techniques are rapidly emerging as powerful tools for the quality control of medicinal plants and plant derived products [1]. These approaches offer enormous advantages over traditional analyses like HPLC-UV in terms of efficacy and analysis time [2]. In this study, principal component analysis (PCA) of 600MHz ¹H NMR spectra of Thymus vulgaris L. aerial parts DMSO-d ₆ extracts has been employed for the discrimination of 15 different Thymus vulgaris L. lots. Extracts have been prepared through a one-step extraction procedure using DMSO-d ₆ as solvent and directly analyzed by means of ¹H NMR spectroscopy. The obtained ¹H NMR spectra have been integrated to yield 189 variables and subjected to PCA analysis using a total of 8 principal components. The PCA model explains 98.9% of the total variance, whereas the first three components account for 87.9% of the total variance. The developed method allowed a fast and efficient differentiation of the samples under investigation and represents the starting point for a new approach in the quality control of Thymus vulgaris L. sample lots.

Acknowledgements: This work was financially supported by Bionorica AG, Kerschensteinerstraße 11–15, 92318 Neumarkt, Germany.

References: 1. Holmes, E. et al. (2006) Planta Med. 72:771–785. 2. Seger, C. et al. (2007)J. Proteome Res. 6:480–497.