Characterization of polyphenolic constituents from Sanguisorba officinalis L. and its antibacterial activity Abstract Sanguisorba officinalis L., one kind of perennial plants, has been widely distributed in southern Europe, northern Africa and China. The objective of the present work was to evaluate the antibacterial captivities of polyphenolic extract (PE) of S. officinalis L. on five pathogenic bacteria, including Gram-negative bacteria (Escherichia coli and Salmonella typhimurium) and Gram-positive bacteria (Staphylococcus aureus, Listeria monocytogenes and Bacillus subtilis). The antibacterial activities were determined by the diameter of inhibition zone, minimum inhibitory concentration and minimum bactericidal concentration tests. The results showed that purified PE had significantly better performance in inhibiting bacteria than crude PE (P < 0.05), and PE had better inhibition effect on Gram-positive bacteria than Gram-negative bacteria. Using LC–ESI–QTOF–MS/MS technology, a total of 44 polyphenolic compounds were tentatively identified, 26 of which have been discussed for the first time in S. officinalis L. Gallic acid, ellagic acid, catechin and their derivatives, which have been identified as antibacterial bioactivities previously, were the major constituents with the amounts of 10, 8 and 11, respectively. Besides, compared with potassium sorbate and sodium benzoate, purified PE with a low concentration had significantly stronger antibacterial ability against all the tested bacteria (P < 0.05), suggesting that purified PE of S. officinalis L. could be a promising source of food preservatives.