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Antioxidant and antimicrobial activity of linseed lignans and phenolic acids
- Kyselka, Jan, Rabiej, Dobrochna, Dragoun, Miroslav, Kreps, František, Burčová, Zuzana, Němečková, Irena, Smolová, Jana, Bjelková, Marie, Szydłowska-Czerniak, Aleksandra, Schmidt, Štefan, Šarman, Luděk, Filip, Vladimír
- European food research & technology 2017 v.243 no.9 pp. 1633-1644
- Gram-negative bacteria, Gram-positive bacteria, antimicrobial properties, antioxidants, bioactive compounds, caffeic acid, chromatography, ferulic acid, hydrolysis, levulinic acid, lignans, linseed, lipid peroxidation, mass spectrometry, median effective concentration, molds (fungi), oxidation, p-coumaric acid, pressing, reaction kinetics, secondary metabolites, solvents, stoichiometry, triacylglycerols, yeasts
- In this study, we present antioxidant and antimicrobial activity of isolated lignans freed of other bioactive compounds in comparison with dominant phenolic acids. The combinations of screw pressing, solvent extractions, acid-catalysed hydrolysis and flash chromatography were used to describe and isolate linseed phenolic compounds. Secoisolariciresinol, ferulic, p-coumaric and caffeic acids were the most abundant ones while salicylic, gentisic, dihydro-p-coumaric, phenylacetic, vanillic, p-hydroxybenzoic and β-resorcylic acids were the minor secondary metabolites. Anhydrosecoisolariciresinol (ANHSECO) and levulinic acid were an artefacts formed during exhaustive hydrolysis. The effective concentration (EC₅₀), antiradical power (1/EC₅₀), stoichiometry (2·EC₅₀) values and second order rate constants k ₂ were determined to classify antioxidants according to reaction kinetics as slow (p-coumaric acid derivatives), medium (ferulic acid derivatives, secoisolariciresinol and ANHSECO; k ₂ ranges from 1.85 to 2.29 μmol⁻¹ dm³ s⁻¹) and fast (caffeic acid derivatives; k ₂ = 6.91 μmol⁻¹ dm³ s⁻¹) ones. Rancimat method was simulating lipid peroxidation and its inhibition. Linseed lignans and phenolic acids could be classified according to protection of unsaturated triacylglycerols in the following order: p-coumaric acid < ANHSECO < methyl p-coumarate < ferulic acid < secoisolariciresinol < methyl ferulate < crude extract < caffeic acid < methyl caffeate. The mechanism and the formation of secoisolariciresinol oxidation products were discovered by mass spectrometry. The effect of crude linseed extract, ANHSECO, caffeic, ferulic and p-coumaric acid on the growth of Gram-negative bacteria, Gram-positive bacteria, yeasts and moulds was also determined.