Simple non-specific enzymatic oxidation method for studying the bioactivity of phenolic compounds in plants

A new oxidation method was developed to reveal species- and tissue-level bioactivity of plants. The method combines an existing alkaline oxidation method [1] with an in situ enzymatic oxidation step. Plant samples are incubated in an oven after freezing, enabling polyphenol oxidase (PPO) and other oxidizing enzymes getting into contact with phenolic compounds in the plant, resulting in oxidation of the compounds. As the results are analyzed using total phenolics assay on well plate reader and ultrahigh-performance liquid chromatography coupled to a diode array detector and mass spectrometer (UHPLC-DAD-MS), alterations in the levels of total phenolics and individual compounds can be observed. Depending on the available equipment in a laboratory, either of the analysis methods or both can be utilized.