Targeted Screening for Active Flavonoids From Medicinal Extracts to Trap Methylglyoxal: Scutellaria barbata Herba as a Case Study

Methylglyoxal (MGO) is a highly reactive carbonyl species that modifies proteins, leading to the formation of advanced glycation end products (AGEs), which contribute to diseases such as diabetes and cardiovascular disorders. Certain flavonoids, including quercetin and luteolin, can trap MGO, thereby preventing AGE formation. However, traditional screening methods for identifying MGO-trapping flavonoids are inefficient and not suitable for high-throughput analysis. In this study, a novel screening approach was developed utilizing electrospray ionization mass spectrometry with data-dependent acquisition and neutral loss scanning (ESI-DDA-NL). Data-dependent acquisition enhances the quality of tandem mass spectra. By analyzing MS/MS fragmentation patterns, flavonoids that had formed adducts with MGO were identified based on a characteristic 72.0206-Da mass increase and a neutral loss fragment (C3H4O2, 72.0206 Da). This approach enabled the rapid identification of 10 active flavonoids from Scutellaria barbata herba extract. Among these, luteolin, quercetin, naringenin, and apigenin were already known MGO-trapping agents, while scutellarein, hispidulin, nepetin, 6-methoxyerythrictyol, 6-methoxynaringenin, and 4'-hydroxywogonin were newly identified as MGO-trapping agents. Scutellarein and hispidulin were further validated through individual MGO reactions. ESI-DDA-NL is an effective method for screening active flavonoids in traditional Chinese medicine that are capable of trapping MGO.