Comparative Chromatographic Analysis of Amino Acids in the Seeds of Three <i>Nigella</i> L. Representatives

Amino acids are an important class of primary metabolites that can exhibit various pharmacological activities. In this study, the comparative gas chromatography-mass spectrometry (GC/MS) analysis of free and total amino acids in the seeds of three representatives of the Nigella L. genus (Nigella arvensis L., Nigella damascena L. [cultivar "Rizdvyana zirochka"], and Nigella sativa L. [cultivar "Faraon"]) was conducted under their cultivation in Ukraine. Regarding the free state of amino acids, 11 were detected in the raw material of N. damascena, and 9 were found in both N. sativa and N. arvensis. It was found the highest content of L-aspartic acid, specifically 50.359 mg/g in N. damascena (cultivar "Rizdvyana zirochka"), 33.816 mg/g in N. sativa (cultivar "Faraon"), and 31.028 mg/g in N. arvensis. It was revealed that L-leucine, L-valine, and L-tyrosine dominated among the essential amino acids detected in the free state in the seeds of all studied samples. L-glycine and L-proline had the highest amounts among the semiessential amino acids, while L-aspartic acid, L-glutamic acid, and L-phenylalanine are predominant in the nonessential group. Some of the detected in the Nigella sp. amino acids possess significant therapeutic potential.