Use of ultra-high-performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry system as valuable tool for an untargeted metabolomic profiling of Rumex tunetanus flowers and stems and contribution to the antioxidant activity

Rumex tunetanus is an untapped resource with no available information about their chemical composition. That is why, the present study has conducted comprehensive metabolites profiling of the hydromethanol extracts of the Rumex tunetanus flowers and stems using RP-UHPLC-ESI-QTOF-MS. As results, 60 compounds were characterized for the first time in Rumex tunetanus between them, 18 photochemical were firstly identified in the Polygonaceae family in negative ionization mode. In this regard, quercetin-3-O-glucuronide and (-)-epicatechin gallate were the most abundant phenolic compounds in flowers and stems, respectively. Moreover, positive correlations were found between the antioxidant activity measured by DPPH and FRAP assays with the total phenolic compounds (r = 0.98; r = 0.99, respectively) and the abundance of some phenolic subfamilies such as hydroxycinnamic acids, hydroxybenzoic acids, flavonols and flavones with r > 0.86. The compounds displaying significant (P < 0.01) and good correlations with the antioxidant activity (r > 0.93) were hydroxybenzoic acid, rutin, quercetin-3-O-glucuronide, quercetin-3-O-glucoside, quercetin and luteolin-7-O-rutinoside, In conclusion, Rumex tunetanus flowers and stems showed different bioactive compound profiles and significant antioxidant properties and could be further used in food and nutraceutical industries. (C) 2018 Elsevier B.V. All rights reserved.