Identification of <i>Synedrella nodiflora</i> secondary metabolites by UHPLC-MS dereplication

Abstract Ultra-high-performance liquid chromatography-quadrupole-orbitrap-tandem mass spectrometry (UHPLC-Q-Orbitrap MS/MS) dereplication is an emerging technology. The current work used the technology to analyze the twigs of Synedrella nodiflora (L.) Gaertn, a plant with dual roles. Through UHPLC-Q-Orbitrap MS/MS dereplication analysis, 43 secondary metabolites ( 1–43) have been found in this plant for the first time. Particularly, seven isomers were successfully separated from each other, including a pair of oleanane-type saponin isomers (chikusetsusaponin Iva and zingibroside R1). Furthermore, the contents of 43 compounds were evaluated using the UHPLC-Q-Orbitrap MS/MS dereplication analysis. It was observed that pedunculoside showed the highest content (1253.21 ± 26.41 μg/g material) and rutin had the lowest content (0.30 ± 0.01 μg/g material). In addition to chemical content, the antioxidant activities of all 43 compounds were also estimated using 2,2′-azino-bis (3-ethylbenzo-thiazoline-6-sulfonic acid) radical (ABTS ·+ )-scavenging assay and then their antioxidant contributions to the whole twigs were individually calculated using the formula: chemical content × ABTS ·+ -scavenging antioxidant percentage. The calculation results indicated that pedunculoside and protocatechuic acid exhibited the highest antioxidant contributions. According to quantum chemical results, UV–Vis experiment results, and quality-marker (Q-marker) principles (e.g., testability, pharmacology-relevance, traceability, specificity, and non-industrialization), pedunculoside, momordin Ic, zingibroside R1, and protocatechuic acid were proposed as medicinal Q-markers of S. nodiflora twigs. Therefore, it can be concluded that (1) S. nodiflora twigs have drug development potential. (2) The four medicinal Q-markers can be used for the quality-control of S. nodiflora twigs through LC-MS analysis. (3) The UHPLC-Q-Orbitrap MS/MS dereplication is a powerful tool for plant resource development.