Quantification of Glucosinolates in Seeds by Solid-State 13C-Nuclear Magnetic Resonance (NMR)

Solid-state 13C NMR spectroscopy using cross-polarization magic-angle spinning is a highly valuable technique for the semi-quantitative analysis of complex solid matrices. One of its key advantages is that it does not require any manipulation of the matrix, such as extractions or other treatments, which is particularly important for preserving the integrity of unstable secondary metabolites. Glucosinolates (β-thioglucoside-N-hydrosulphates) are crucial secondary metabolites specific to Brassica species, and many of them are known to be highly unstable. In this study, we evaluated solid-state nuclear magnetic resonance spectroscopy as an alternative method for the identification and quantification of total glucosinolates in the seeds of Sisymbrium officinale, Brassica napus, Sinapis alba, Brassica nigra, and Moringa oleifera. The results obtained with this method showed good agreement with those from conventional chemical analyses of the seed material. Although, based on a limited number of samples, this preliminary study suggests that the proposed approach could be a useful alternative for quantifying total glucosinolate content in seeds.