Comparing the Metabolic Characteristics of Hyacinth Bean (Lablab purpureus L.) Seeds from Five Local Varieties by UHPLC-QE HF HRMS

Hyacinth bean seeds are a good source of vegetable protein and have great potential for medicinal development. However, their metabolic characteristics are unclear. Therefore, in this study, we conducted non-targeted metabolomics research on hyacinth bean seeds from local varieties using ultra-high-performance liquid chromatography combined with high-field quadrupole orbital trap high-resolution mass spectrometry (UHPLC-QE HF HRMS) and evaluated their antioxidant properties. A total of 745 metabolites were identified, including many bioactive medicinal compounds such as chikusetsusaponin IVa, pipecolic acid, and genistin. The seed coat color and origin of hyacinth bean seeds have significant impacts on their metabolic characteristics. Compared with the other four hyacinth beans, the Chongming white hyacinth bean (SCLW) has a higher medicinal value, with glycitin, finsenoside Ro, diferuloyl glycerol, isopongflavone, procyanidin B2, and pratensein speculated to be its characteristic metabolites. DPPH and FRAP assays showed that the antioxidant activity of SCLW was significantly higher than that of the other four hyacinth bean seeds, and 11 metabolites related to antioxidant activity were identified. These findings enrich our knowledge of the metabolites in hyacinth bean seeds, which is of great significance for hyacinth bean cultivation according to local conditions and for the improvement of variety quality.