Currently, mass spectrometry-based approaches constitute the primary strategy for the dereplication of flavonoid glycosides; however, strategies focused on the dereplication of their isomers are still scarce. On the other hand, although flavonoid glycosides frequently occur in the leaves of the Annonaceae family, some species, such as Onychopetalum periquino, remain understudied on this topic.

The aqueous extract from the leaves of O. periquino was filtered through celite and eluted with methanol. The methanol fraction was analyzed by DI-MS in data-dependent acquisition (DDA) mode with neutral loss scans for flavonoid glycosides recognition. Finally, a set of presumable flavonoid glycosides isomers was analyzed by LC-MS/MS and dereplicated through manual interpretation of MS/MS spectra.

DI-MS analysis revealed the presence of flavonoid glycoside isomers, primarily derived from apigenin, luteolin, and quercetin, which were duly dereplicated through LC-MS/MS analysis as follows: vitexin (1), isovitexin (2), apigenin 7-O-glucoside (3), luteolin 6-C-glucoside (4), luteolin 8-C-glucoside (5), luteolin 7-O-glucoside (6), isoscoparin (7), chrysoeriol 7-O-glucoside (8), diosmetin 7-O-glucoside (9), apigenin 8-C-neohesperidoside (10), apigenin 6-C-neohesperidoside (11), apigenin 7-O-rutinoside (12), quercetin 3-O-glucoside-7-O-rhamnoside (13), and quercetin 3-O-rutinoside (14).

This study demonstrated the efficacy of the proposed strategy in identifying and differentiating flavonoid glycoside isomers in O. periquino leaves. Therefore, this workflow is an effective approach for the comprehensive characterization of flavonoid glycoside isomers in future dereplication works. Additionally, it showed how structural differences, such as the type of linkage and position of sugars, influence their fragmentation patterns.