LC–NMR, NMR, and LC–MS identification and LC–DAD quantification of flavonoids and ellagic acid derivatives in Drosera peltata

•Qualitative and quantitative analysis of phenolics in the sundew Drosera peltata.•Identification of 13 flavonoids and ellagic acid derivatives by LC–MS and (LC-)NMR.•Five compounds have not been detected in any Drosera species before.•Quantification of major compounds by a validated narrow-bore HPLC method.•Notable differences in composition to other therapeutically used Drosera species.

The herb of Drosera peltata, commonly named the shield sundew, is used as an antitussive in phytotherapy, although the plants’ composition has not been determined in detail so far. Hence, in this study, we present a validated, sensitive, reliable, and cheap narrow-bore LC–DAD method for the simultaneous quantification of flavonoids and ellagic acid derivatives in this herbal drug. In addition, the structures of 13 compounds have been elucidated by LC–MS, LC–NMR, and offline NMR experiments after isolation: herbacetin-3-O-glucoside (1), gossypitrin (2), ellagic acid (3), quercetin-7-O-glucoside (4), isoquercitrin (5), kaempferol-3-O-(6″-O-galloyl)-glucoside (6), herbacetin-7-O-glucoside (7), astragalin (8), gossypetin (9), herbacetin (10), quercetin (11), 3,3′-di-O-methyl ellagic acid (12), and kaempferol (13). Compounds 1, 2, 4, 5, 6, 7, and 10 have been identified in D. peltata for the first time, and compounds 1, 4, 6, 7, and 10 have not been detected in any Drosera species before.