A rapid profiling of gallotannins and flavonoids of the aqueous extract of Rhus coriaria L. by flow injection analysis with high-resolution mass spectrometry assisted with database searching

Hydrolysable tannins appear to have some extremely important biological roles including antioxidant,antibacterial, anti-inflammatory, anti-hypoglycemic, anti-angiogenic, and anticancer activities. The aimof this work was to set up a flow injection high-resolution mass spectrometric approach combined withdatabase searching to obtain rapidly a profiling of gallotannins and other phenolics in a crude extract fromplant tissue. The flow injection analysis (FIA) takes place in an electrospray ionization source of an hybridorbitrap high resolution mass spectrometry system (ESI–HR-MS/MS2, resolution 100,000, negative ionmode) and polyphenols are tentatively identified by matching the monoisotopic masses of the spectrawith those of polyphenols databases.This leads to the most probable molecular formulas and to the possible structures among those reportedin the database. The structures confirmation occurs by the compliance of MS2 fragments with those of aprediction fragment commercial database.With this method we identified in the aqueous extract of sumac leaves, with a maximum error of1.7 ppm, a group of ten gallotannins from mono- to deca-galloyl glycosides of the class of hydrolysabletannins and a set of coextracted flavonoid derivatives including myricetin, quercetin-3-O-rhamnoside,myricetin-3-O-glucoside, myricetin-3-O-glucuronide, and myricetin-3-O-rhamnoglucoside.The separation of isomers of gallotannins and flavonoids present in the same extract occurredby high-performance liquid chromatography with electrospray ionization tandem mass spectrometry(HPLC/ESI–HR-MS2); this approach allowed the structure resolution of the isobaric flavonoids quercetin-3-O-glucoside and myricetin-3-O-rhamnoside.