Screening Brazilian collard cultivars for glucosinolate content

Collard is one of the most consumed leafy vegetables in Brazil, being very important in the diet of the Brazilian population as a source of vitamins and antioxidants. Among the most important antioxidants are glucosinolates (GSs), whose compounds contain sulfur molecules in their molecules that act to prevent cancer. Sinigrin (2propenylglucosinolate) is a secondary metabolite of the plant glucosinolate group, and occurs naturally in Brassica plants with significant quantities. In this work, the objective was to evaluate the concentration of sinigrin in 29 collard cultivars produced and consumed in the federal district, Brazil, and to study its interaction with minerals' soil level. Samples of green collard leaves were harvested from different fields, one leaf per plant, and soil was collected in different points of cultivation, forming a composite sample. A reversed phase-high performance liquid chromatography (HPLC) method was used to quantify sinigrin content of freeze-dried leaf samples. The cultivar HI61 had the highest total glucosinolate content, which was 219.46 μmol 100 g^‑1 DW, followed by DB74 (178.58 µmol 100 g^‑1 DW) and EN42 (169.63 μmol 100 g^‑1 DW). The lowest total GSs content was 1.00 μmol 100 g^‑1 DW with cultivar MC47. The results showed that Vargem Bonita presented the highest concentration of sinigrin and had also the highest value for organic matter, Ca and Mg and P. These findings showed that Brazilian collard varieties showed great variation in their glucosinolate content, and might be influenced by soil mineral fertilization. Thus, cultivars with high glucosinolate contents could be used in Brazilian breeding programs to improve commercial cultivars, whose compounds are beneficial to human health.