HPLC-DAD-ESIMS Analyses of Hyoscyamus niger and H. reticulatus for their Antioxidant Constituents

Different extracts from leaves, epicalyxes and seeds of the plants Hyoscyamus niger and H. reticulatus were subjected to total phenolic measurements using Folin-Ciocalteu reagent and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays and high performance liquid chromatography (HPLC-UV) analyses. Among the tested plant's extracts, the 80% methanol extracts of H. reticulatus leaves (173.1±0.0), H. reticulatus epicalyxes (183.3±10.1), H. niger leaves (221.3±26.6) and H. niger epicalyxes (362.3±11.6) had lower IC50s (μg plant extracted/1 mL 10-4 M DPPH) which were in agreement with the increasing order of their total phenolic contents. The constituents of the most active 80% methanol extracts of H. niger and H.reticulatus were determined by HPLC-Diode Array Detector-Electrospray Ionization Mass Spectroscopy (LC-DAD-ESIMS). Three major phenolic constituents were identified and quantified: chlorogenic acid, rutin and Quercetin-3O-Glucoside-Rhamnoside-Rhamnoside (QGRR). In this paper, we correlate the antioxidant activity of the plants extracts with the concentrations of their phenolics.