Evaluation of free amino acids in Cirsium vulgare (Bull thistle) plant materials using gas chromatography–mass spectrometry

Amino acids are one of the main particles in a living organism. They perform many different functions, such as structural, receptor, energetic and enzymatic functions [1]. The aim of the investigation was to identify and evaluate the qualitative composition of free amino acids in samples of Cirsium vulgare material using gas chromatography–mass spectrometry (GC-MS). Our objectives were to apply the gas chromatography– mass spectrometry (GC-MS) method for free amino acids from Cirsium vulgare raw materials grown in Lithuania and determine the qualitative composition of free amino acids from extracts of Cirsium vulgare raw materials: roots, leaves, flowers and seeds. MTBSTFA (N-methyl-N-(tertbutyldimethylsilyl) trifluoroacetamide) was selected for derivatisation in free amino acid analysis. Applying gas chromatography–mass spectrometry with compound derivatisation and based on the mass spectral database free amino acids were identified in bull thistle raw material: L-alanine, glycine, L-valine, L-leucine, L-isoleucine, L-proline, L-serine, L-threonine, L-phenylalanine, L-lysine, L-tyrosine, L-aspartic acid and L-glutamic acid. Studies have shown that the qualitative composition of free amino acids depends on the plant vegetation phase and plant parts.