The aim of our study was to identify phenolic compounds in the root peels and young shoots of Japanese knotweed (Fallopia japonica), Giant knotweed (Fallopia sachalinensis) and Bohemian knotweed (Fallopia × bohemica). We collected plant material and prepared ethanol extracts of the samples. With DPPH• method we determined antioxidant efficiency of knotweed extract, where higher Trolox equivalent antioxidant capacity was determined in the root peel extracts compared to the young shoots ones. Separation of phenolic compounds was performed by reverse phase chromatography followed by ionization with scattering in an electric field. We then characterized the phenolic compounds with high resolution and tandem mass spectrometry. We used data from mass spectrometric libraries as a tool for identification where we proposed emodin-8-o-β-D-glucoside, procyanidin B1, procyanidin C1, taxifolin and epicatechin gallate. We confirmed the compounds with reference standards of phenolic compounds. We identified catechin or epicatechin, polydatin, resveratrol, emodin, piceatanol, epigallocatechin gallate, quercetin, chlorogenic acid and ferulic acid. Content of compounds among extracts is different. We found that liquid chromatography coupled with mass spectrometry is a useful method for the successful identification and characterization of phenolic compounds and more research for identification and characterization in knotweed is needed.
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