Identification and quantification of flavonoids in edible dock based on UPLC-qTOF MS/MS and molecular networking

Abstract

Edible dock, also known as Rumex patientia L.×Rumex tianschanicus A. LOS., exhibiting the characteristics of high yield, high protein and high nutrition, is widely used in the functional food industry and Chinese herbal medicine while short of secondary metabolites research. This study used UPLC-qTOF MS with two ion polarity in conjunction with Molecular Networking from Global Natural Products Social (GNPS) platform. Then, these 16 flavonoid substances including quercetin derivatives and kaempferol derivatives, firstly were identified from leaves in edible dock and were systematically investigated by UPLC-qTOF MS/MS. MS/MS experiments found that quercetin derivatives have five common characteristic ions, including m/z 300, m/z 271, m/z 255, m/z 243, and m/z 151. In addition, kaempferol derivatives have three common characteristic ions, including m/z 284, m/z 255, and m/z 227. Subsequently, 7 representative constituents were quantified via UPLC-QQQ MS with chemometrics, and the total content of 7 major flavonoids in its dry leaves is 6.988 mg/g in the 21st day samples. The work provided abundant metabolites information of flavonoids in edible dock, and the common characteristic ions will facilitate the building blocks-based molecular network (BBMN) to predict novel framework compounds from quercetin derivatives and kaempferol derivatives, laying the basis for exploitation of edible dock in the fields of pharmaceuticals, health food, and livestock feed.