Comprehensive structural characterization of phenolics in litchi pulp using tandem mass spectral molecular networking

Phenolic compounds are a large class of plant secondary metabolites with various health-promoting effects, and are known for their structural diversity. Therefore, high efficiency characterization of phenolic profiles is of key importance in identifying their potential bioactivity. In the present study, Global Natural Products Social (GNPS) Molecular Networking was applied to trace the phenolic compounds in plants, which allowed the characterization of 9 procyanidins and 11 flavonoid glycosides (di-, tri-, or tetra-saccharides of kaempferol, quercetin, isorhamnetin and myricetin) in litchi pulp extracts. Six compounds were reported for the first time in litchi pulp. In addition, quercetin-3-O-rutinoside-(1 -> 2)-O-rhamnoside, the most abundant flavonoid glycoside in litchi pulp, was proved to have considerable a-glucosidase inhibitory activity, illustrating the anti-diabetic potential of phenolic-rich litchi pulp extracts.