Detection of bioactive coffee compounds by TLC-ESI-MS using QuEChERS concept

The green coffee bean is one of the main arrays of the chemistry of natural products. It presents several bioactive compounds, among them, caffeine (CAF), chlorogenic acids (CGA) and diterpenes cafestol and kahweol (DIT). These compounds are associated with effects on the purinergic system, dyslipidemia, cardiovascular protection and diabetes.1,2 As they have different chemical characteristics, such as polarity, the methodologies of extraction and analysis of these compounds have been a challenge., for the best of our knowledge, no methodology has been capable to achieve a mixture of these bioactive molecules in a purified form, evidencing an important gap in the experimental area. The TLC (Thin Layer Chromatography) technique appears as a key device in innovation and simplicity, opening perspectives where expensive methods have been dominant. TLC has several advantages, such as the small amount of samples and solvents used and the speed of the analyzes.3 The use of modern TLC and the coupling with mass spectrometers (TLC-MS, Thin Layer Chromatography – Spectrometer Mass) as detection devices brought to this is old technique a new concept of modern sustainability.4 The objective of this work was to detect the main bioactive compounds present in coffee beans using the QuEChERS (Quick, Easy, Cheap, Effective, Robust, Safe) concepts,5 with a development a methodology to clean up other substances present, such as fatty acids and glycosides, following an identification process using TLC-ESI-MS technique. Several solvent combinations were tested for extraction and the chloroform/acetone system is the best result for the concentration of the substances of interest. A brief analysis of the HPTLC plates by TLC-MS allowed the detection and identification of the compounds present in the extract, obtaining the molecular ions of diterpene kahweol ([M-H]- 313.0), caffeine ([M + H]+ 195.1) and of the 5-Caffeoylquinic acid CGA ([M - H]- 353.1). The methodologies employed allow the extraction and efficient concentration of compounds of interest, facilitating the identification by TLC-ESI-MS