Rapid characterization of metabolites in soybean using ultra high performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry (UPLC-ESI-Q-TOF-MS/MS) and screening for α-glucosidase inhibitory and antioxidant properties through different solvent systems

Abstract

This work was the first to investigate on the simultaneous characterization of metabolite profiles in soybean using UPLC-ESI-Q-TOF-MS/MS. Twenty two compositions were observed within 14 min from the methanol extract and confirmed as twelve isoflavones of three types and ten soyasaponins (Ab, Af, I-III, αg, βg, βa, γg, and γa). Moreover, the patterns of two chemicals showed considerable differences in seven solvent systems by HPLC analysis and their optimal extraction was achieved by 70% methanol (isoflavone: 4102.69 μg/g; soyasaponin: ten peaks). The second abundant isoflavones were detected in 50% methanol (4054.39 μg/g), followed by 30% methanol, 100% methanol, 10% methanol, CH₂Cl₂, and acetone extracts with 3134.03, 2979.49, 1681.33, 366.19, and 119.00 μg/g, respectively. Soyasaponins exhibited similar tendencies as those of isoflavones. The highest total phenolic was found as 2.10 ± 0.05 mg GAE/g in 70% methanol with remarkable differences by comparing other extracts. Specifically, this extract showed potent α-glucosidase inhibitory (81%) and antioxidant capacities (DPPH: 93% and ABTS: 95%) at a concentration of 1.0 mg/mL. Our results may be contributed to enhancing the value to functional foods and evaluating the secondary metabolites concern to antioxidant properties using solvent system in soybean.

Keywords: Antioxidant; Isoflavone; Soyasaponin; UPLC-ESI-Q-TOF-MS/MS; α-Glucosidase.