1H NMR Metabolomic analysis of coffee and tea samples for the quantative determination of the main constituents

In metabolomics the aim is to detect and quantify all metabolites present in a certain organism, tissue or cell at a specific moment. One of the major problems in the analysis is the incomplete extraction [1]. In NMR based metabolomics generally aqueous solutions are used. In studies with humans or animals, where the samples are generally derived from body fluids this seems logic, but in plants a much larger variety of metabolites is encountered and the metabolites are obtained through the extraction of tissues. For the analysis of samples of tea and coffee the extraction procedure was investigated. Direct extraction with commonly used NMR solvents, did show that no single solvent provided a complete profile, but the best results were obtained with an extraction with a two-phase system consisting of water and chloroform. Water was found to be essential to obtain a good extraction of the apolar constituents with chloroform. The direct use of chloroform on dried plant material yielded incomplete extractions.

The application of the developed protocol on the coffee and tea samples permitted an accurate quantification of the caffeine content and the detection of specific metabolites in different types of coffee and tea.

Acknowledgement: CNPq, FAPERJ, CAPES.

References: 1. Schripsema J (2010) Phytochem Anal 21: 14–21