Metabolom- und Transkriptom-Analysen zur Charakterisierung von pflanzlichen Substanzen und daraus hergestellten Zubereitungen = Metabolomic and Transcriptomic Analyses in the Characterization of Herbal Substances and their Preparations

Abstract

Herbal substances and preparations thereof have been applied and used worldwide throughout human history. Regarding regulatory affairs, the quality assessment of herbal substances and their preparations is mandatory. Quality control is challenging, as herbal substances and their preparations are always complex mixtures; therefore, a comprehensive characterization is of major impact. <br /> The focus of the present thesis was to bridge data about the chemical profile and the biological activity of herbal preparations. The strategy involved analytical methods like high pressure liquid chromatography and 1H-NMR analysis in combination with principal component analysis (PCA). In parallel, techniques used for the investigation of functional activity (cell proliferation analysis and gene expression profiling after treatment of HepG2 cells) were applied. Preparations containing Chelidonii herba, Cimicifugae racemosae rhizoma or Silybi mariani fructus were characterized by this multidisciplinary approach. Characteristic preparation-specific patterns were observed by PCA and gene expression profiling for differently produced herbal preparations. Investigations on the reproducibility of microarray analysis indicated higher congruency for at least threefold regulated genes. A higher variance of the data was identified for significantly regulated genes with low fold changes.<br /> A subproject of this thesis evaluated in detail the potential of the metabolomics-based method and a polymerase chain reaction (PCR)-based approach using molecular markers, applied for the authentication and identification of herbal substances. Thereby, it was shown that the metabolomics-based approach is highly valuable for a global classification of herbal preparations. Classification of different herbal substances could be achieved up to species level. The analysis of at least two marker sequences is recommended to unambiguously identify the herbal origin.<br /> The comprehensive characterization of complex herbal mixtures by a metabolome-based approach is very useful for authentication of herbal substances and reliable for the discrimination of major constituents. However, regarding phytochemical metabolites present in small amounts only, limitations of the method were shown. For the identification of herbal substances, the PCR-based approach is suitable. <br /> The present thesis provided new insights by bridging data about the chemical profile and gene expression profiles of herbal preparations. The investigation and correlation of both the chemical profile and functional activities is promising to comprehensively characterize herbal substances and their preparations. Regarding specificity, the metabolomics-based approach and gene expression profiling clearly showed characteristic signatures depending on the herbal preparation used. These results show the high importance of a defined manufacturing procedure. However, knowledge in gene regulation and systems biology is still limited and data about signal cascades affected in an in vitro system are only a starting point for further investigations.