Sustainable ultrasound-assisted extraction followed by ultra-high liquid chromatography coupled to ion-trap tandem mass spectrometry for the determination of major and minor quinolizidine alkaloids in Retama monosperma (L.) Boiss seeds

Abstract

This study addresses the development, optimisation and validation of a sustainable analytical procedure for the determination of antinutritional factors (quinolizidine alkaloids, QAs) in legume seeds. The approach proposes the ultrasound-assisted extraction (UAE) of major (i.e., cytisine) and minor (i.e., n-methylcytisine and anagyrine) QAs from Retama monosperma seeds followed by ultra-high performance liquid chromatography coupled to ion- trap tandem mass spectrometry analysis (UHPLC-IT-MS/MS). The procedure was optimised by Response Surface Methodology and fully validated (overall recoveries 86–105% and precision RSD values ≤18%). The method was applied to the analysis of different raw and treated seed samples. Cytisine was the main QA found in the samples, followed by methylcytisine and finally anagyrine. Variations in the concentration of these analytes were observed depending on environmental conditions. Similarly, they showed different behaviour under the different mitigation processes tested. Anagyrine was the most affected by the hydrothermal mitigation treatment. Heat treatment + soaking for several days probed to more effective in QA mitigation than just heat treatment. However, the mitigation procedures tested were not enough to reach a QA concentration safe for consumption. Thus, further research in mitigation strategies is needed to consider R. monosperma seeds as a safe protein-rich source for food and feed.