Development of Analytical Methods and Databases for the Analysis of Polyphenols in Medicinal and Aromatic Plant Extracts

Numbers of epidemiologic studies have shown an inverse correlation between the consumption of fruits and vegetables and mortality from degenerative diseases, such as cancer and coronary heart disease. It is not known which dietary components are responsible of this correlation, but natural antioxidants and especially polyphenols, appear to play an important role in the protective effect of plant foods. The first part of this work was focused on the development of a specific analytical method and database using HPLC-DAD-MS technique for the characterization of naturally occurring polyphenols. The collected data included retention times, UV and MS spectra of thirty-eight reference compounds (phenolic acids and flavonoids). The second part focused on the characterisation of polar extracts prepared from selected medicinal and aromatic plants, followed by a bio-guided fractionation using automated preparative chromatography. The obtained fractions were examined in terms of radical-scavenging activity, and the most active ones were analysed and compared to the developed specific database. This method permitted a rapid, specific and accurate identification of the main bioactive compounds responsible for the antioxidant activity. The analytical procedure described in this work, combining antioxidant bioassays, bio-guided fractionation and sensitive detection is a powerful tool for the identification and measure of natural occurring polyphenols, and thus, for the valorisation of related medicinal and aromatic plants.