Identification of polyphenol extracts from flaxseed and study on its bacteriostatic mechanism

Highlights
The polyphenol extract of flaxseed had inhibitory effect on the five indicator bacteria. The extract
damages the cell structure of microorganisms, thereby inhibiting their growth. The integrity of
the cell wall of P. fluorescens was damaged by the polyphenol extract of flaxseed. Sinapic acid
and quercetin were the dominant phenolics in flaxseed polyphenol extract.
Abstract
In this paper, the polyphenol components of flaxseed were identified, and their antibacterial
effect and mechanism of action against pathogenic bacteria were studied. Results showed that 14 phenolic acids and 15 flavonoids were identified in flaxseed. Among them, 5 phenolic acids,
including ferulic acid, vanillic acid, sinapic acid, gallic acid, 4-hydroxybenzoic acid, as well as
6 flavonoids, including vitexin, quercitrin, quercetin, apigenin, kaempfero1, (+)-dihydroquercetin,
were the main phenolic compounds in flaxseed and have been quantitatively analyzed and
determined. The content of sinapic acid and quercetin accounted for over 42.67% of flaxseed
polyphenol extract. The Oxford Cup method confirmed the antibacterial effect of flaxseed
polyphenol extract on Staphylococcus aureus, Escherichia coli, Listeria
monocytogenes, Salmonella and Pseudomonas fluorescens. The experimental data showed
that flaxseed polyphenol extract had a strong inhibitory effect on the growth of both common
food-borne pathogens and non-food-borne pathogens. Flaxseed polyphenols increased the
permeability of microbial cell membrane, resulting in microbial protein leakage, cell membrane
depolarization, and decreased intracellular ATP content, and increased cell membrane
potential and cell contents leakage. The results of this study clarified the composition of
flaxseed polyphenol and provided a new way for the comprehensive utilization of flaxseed.