Comprehensive characterization of flavonoid derivatives in young leaves of core-collected soybean (Glycine max L.) cultivars based on high-resolution mass spectrometry

Most previous studies have been focused on isoflavone profile with biological activities from soybean seed and its related products. However, in the present study, eighty-three flavonoid derivatives (55 flavonols, 9 flavones and 19 isoflavones) were comprehensively identified and quantified from young leaves of 21 core-collected soybean cultivars based on ultra-performance liquid chromatography-diode array detector with quadrupole time of flight/mass spectrometry (UPLC-DAD-QToF/MS). Among total content (342.5-992.7 mg/100 g, dry weight) of 83 derivatives found in these soybean leaves (SLs), the abundant flavonols (83.6%, 275.1–854.0) were primarily composed of 26 di- and 23 tri- glycosides combined to the aglycones (K, kaempferol; Q, quercetin; I, isorhamnetin), and distributed in the order of K, Q and I. Particularly, K-rich SLs (yellow coated seed), Nongrim 51 (breeding line) and YJ208-1 (landrace) contained mainly kaempferol 3- O -(2"- O -glucosyl-6"- O -rhamnosyl)galactoside and 3- O -(2",6"-di- O -rhamnosyl)galactoside, and were expected to be superior cultivars by their higher flavonoids. Besides, the new tri-I-glycosides (soyanins Ⅰ~Ⅴ) were presented as predominant components in Junyeorikong (landrace, black). Thus, these detailed profiles will support breeding of superior varieties with excellent biological activities as well as relationship with seed anthocyanins production, and suggest that the SLs can be considered as a valuable edible resource due to their rich flavonoids.