Discovery and Characterization of Phenolic Compounds in Bearberry (Arctostaphylos uva-ursi) Leaves Using Liquid Chromatography–Ion Mobility–High-Resolution Mass Spectrometry

The characterization
and quantification of phenolic compounds in
bearberry leaves were performed using hyphenated ion mobility spectroscopy
(IMS) and a quadrupole time-of-flight mass spectrometer. A higher
identification confidence level was obtained by comparing the measured
collision cross section (TWCCSN2) with predicted
values using a machine learning algorithm. A total of 88 compounds
were identified, including 14 arbutin derivatives, 33 hydrolyzable
tannins, 6 flavanols, 26 flavonols, 9 saccharide derivatives, and
glycosidic compounds. Those most reliably reproduced in all samples
were quantified against respective standards. Arbutin (47–107
mg/g), 1,2,3,4,6-pentagalloylglucose (6.6–12.9 mg/g), and quercetin
3-galactoside/quercetin 3-glucoside (2.7–5.7 mg/g) were the
most abundant phenolic components in the leaves. Quinic acid and ellagic
acid were also detected at relatively high concentrations. The antioxidant
activity of the most abundant compounds was evaluated. A critical
view of the advantages and limitations of traveling wave IMS and CCS
for the discovery of natural products is given.