Comparative analysis of the chemical constituents and in vitro antioxidant activities of different aqueous extracts of the Cistanche phelypaea (L.) Cout. from Algeria

Cistanches herba are well-known for their nutritional and therapeutic effects, but only few reports are available about the species Cistanche phelypaea (L.) Cout. and studies of aqueous extracts are scarce. This study aimed to elucidate the impact of aqueous extraction methods including decoction, infusion and cold maceration from C. phelypaea roots on phytochemical composition and in vitro antioxidant activities of the extracts. In order to accomplish this, determinations of total phenolic and flavonoid contents, liquid chromatography electrospray ionization mass spectrometry (LC/ESI-MS and LC/ESI-MS/MS) analyses and in vitro antioxidant activity studies were carried out. All extracts had significant levels of total phenolic content, but the decoction possessed the highest concentration and no significant difference was observed between infusion and cold maceration. Concerning flavonoids, decoction and infusion possessed the highest concentrations. Data obtained from LC/ESI-MS and LC/ESI-MS/MS analyses showed similar qualitative profiles for all aqueous extracts with 14 characteristic chromatographic peaks in negative mode and 6 in positive mode, which allowed the tentative identification of syringin, 14 phenylethanoid glycosides and 5 iridoids, including 5 pairs of isomers. However, significant variations were recorded for the relative abundance of some compounds depending on the method that was employed. Hot extraction procedures, decoction and/or infusion were more efficient in extracting acteoside, isoacteoside and two molecules corresponding to isomers of 2ʹ-acetylacteoside/tubuloside B, and it seems that a longer time of heating-extraction was required for an improved extraction of isoacteoside, and one of the two isomers of 2ʹ-acetylacteoside/tubuloside B, as decoction gave a significant higher amount of these compounds. However, 8-epiloganic acid and cistanoside F, with their respective isomers, and syringin were more extractable by the cold maceration process. All extracts had similar antioxidant properties in scavenging DPPH radical and total antioxidant activity assays, with the exception of the ferric-reducing power activity assay, in which cold maceration exhibited a significantly less potent activity. Aqueous extracts of C. phelypaea roots present an interesting antioxidant potential which is related to the synergistic effects of several antioxidant compounds.