Metabolomics driven analysis of Nigella sativa seeds identifies the impact of roasting on the chemical composition and immunomodulatory activity.

Nigella sativa L. seeds (NS) are known as one of the most traditional immunomodulatory and nutritive food additives. NS can, furthermore, be roasted to give curries, breads, and other dishes a smoky, nutty flavor. This study evaluated the effect of roasting NS on the metabolic profile and immunomodulatory activity. Non-targeted metabolomics analysis was conducted using several analytical platforms, including GC-MS and UPLC-MS. A total of 197 metabolites were identified, belonging to different classes such as saponins, alkaloids, flavonoids, and lipids. In vitro immunomodulatory activity on the differentiated monocytic cell line THP-1 was assessed, revealing that the roasted seeds showed significantly-decreased immunomodulatory activity. Furthermore, a molecular docking study, which was carried out against immunomodulation-related pathway protein (iNOS), revealed that compounds which showed the best binding scores were severely decreased by roasting. Conclusively, our results demonstrate that the roasting of NS results in severe losses in their bioactive metabolites and immunomodulatory activity.