Comprehensive Polyphenolic Profiling of Nine Distinct Plants and Edible Mushrooms by Targeted and Untargeted LC-(HR)MS(/MS)

Polyphenols are a broad molecular family whose presence in an organism is mostly only partially known. They are secondary metabolites exhibiting antioxidant properties and are involved in a wide range of biological actions. Moreover, polyphenol oxidases, metalloenzymes present in various plants and fungi, play a role in metabolic pathways by catalyzing the hydroxylation and oxidation of polyphenols. Functional studies on these enzymes are greatly hampered by the lack of information on the polyphenols present in a specific organism, so the physiological substrate is unknown for most polyphenol oxidases. Therefore, seven commercially available fungal and two plant species were examined in detail for the presence of polyphenols using an LC-HRMS-based suspect screening workflow. A total of 401 features were annotated, composed of 221 flavonoids and 180 non-flavonoids. As 64% of the flavonoids were conjugated with a glycone, (semi-)quantification was applied when a reference standard of the aglycone was available. Isomers of hesperetin-O-glucoside were ubiquitous in all investigated samples. The samples were then additionally investigated by a quantitative, targeted LC-MS/MS assay that covers 90 polyphenols from 13 distinct polyphenol classes. The targeted assay showed phenolic acids as prevalent analytes. Overall, this pilot study provides new insights into the complex polyphenol profiles of nine mushroom and plant species.