Unveiling crucifer metabolomes via UPLC-HRMS/MS and chemometric analysis of edible and non-edible varieties

Cruciferous green vegetables are considered as one of the most important consumed vegetables world-wide owing to their rich nutritive value, characteristic taste as well as health benefits. Cruciferous vegetables are rich in a myriad of bioactive phytochemicals including phenolic compounds and glucosinolates (GLS). The current work aims to assess heterogeneity in secondary metabolites profile among six cruciferous green leafy vegetables including Brassica oleracea (cabbage), B. oleracea var. Italica (broccoli), B. oleracea var. oleracea (cauliflower), B. rapa (turnip), Raphanus sativus L. (radish), and Nasturtium officinale (watercress) using UHPLC-HRMS/MS coupled with chemometric analysis. A total of 149 metabolites were identified belonging to different phytochemical classes including flavonoids, phenolic acids, steroids, anthocyanins, fatty acids/acyl esters, and GLS. Flavonoids were detected as the most abundant class in cruciferous vegetables represented by 48 peaks, especially Broccoli, cabbage and cauliflower. Radish exhibited unique flavonoid profiles including kaempferol-O-pentosylhexoside-O-deoxyhexoside, kaempferol-O-hexosyl-O-di-deoxyhexoside, and quercetin-O-tri-deoxyhexoside, along with indole-derived GLS known as methoxyspirobrassinin. Distinct phenolic acid profile was observed where di-sinapoyl-O-hexoside was detected only in turnip and broccoli, p-coumaroyl-malic acid was enriched in turnip only, and feruloyl malate and coumaroyl malate were enriched in turnip and radish. Unsupervised PCA analysis revealed distinct variation of turnip from other cruciferous samples, while OPLS-DA distinguished non-edible broccoli from edible cabbage, showing enrichment of neoglucobrassicin and malic acid in broccoli and higher flavonoid and anthocyanin levels in cabbage. These findings highlight the metabolic diversity of cruciferous leaves and support the valorization of underutilized species as potential functional food resources.