Synthesis and Antibacterial Properties of Oligomeric Dehydrogenation Polymer from Lignin Precursors

Abstract

The lignin precursors of coniferin and syringin were synthesised, and guaiacyl-type and guaiacyl-syringyl-type oligomeric lignin dehydrogenation polymers (DHP and DHP-GS) were prepared with the bulk method. The carbon-13 nuclear magnetic resonance spectroscopy showed that both DHP-G and DHP-GS contained β-O-4, β-5, β-β, β-1, and 5-5 substructures. Extraction with petroleum ether, ether, ethanol, and acetone resulted in four fractions for each of DHP-G (C11–C14) and DHP-GS (C21–C24). The antibacterial experiments showed that the fractions with lower molecular weight had relatively strong antibacterial activity. The ether-soluble fractions (C12 of DHP-G and C22 of DHP-GS) had strong antibacterial activities against E. coli and S. aureus. The C12 and C22 fractions were further separated by preparative chromatography, and 10 bioactive compounds (G1–G5 and GS1–GS5) were obtained. The overall antibacterial activities of these 10 compounds was stronger against E. coli than S. aureus. Compounds G1, G2, G3, and GS1, which had the most significant antibacterial activities, contained β-5 substructures. Of these, G1 had the best antibacterial activity. Its inhibition zone diameter was 19.81 ± 0.82 mm, and the minimum inhibition concentration was 56.3 ± 6.20 μg/mL. Atmospheric pressure chemical ionisation mass spectrometry (APCI-MS) showed that the antibacterial activity of G1 was attributable to a phenylcoumarin dimer, while the introduction of syringyl units reduced antibacterial activity.

Lignin–cellulose complexes derived from agricultural wastes for combined antibacterial and tissue engineering scaffolds for cutaneous leishmaniasis wounds

“…4(A), indicating the presence of a G-type dimer structure linked by a β-5 bond (phenyl-coumaran). 49,54…”

“…4(A), indicating the presence of a G-type dimer structure linked by a b-5 bond (phenylcoumaran). 49,54 Overall, the MALDI-TOF MS analysis revealed that the extracted lignin had a maximum molecular weight of around 1374 Da and was made up of three repeating units. In addition, the results further consolidated the fact that SCB, HT1 and HT2 lignins are composed primarily of G-type b-5 dimers, acting as the repeating unit, linked by b-O-4 0 .…”

Antibacterial Synergy Detection of Lignin Extract from Oil Palm Empty Fruit Bunches (Opefb) Combined with Amoxicillin Against Staphylococcus Aureus Using The Azdast Method

“…Each of these compounds originates from different precursors, namely p-coumaryl, coniferyl, and sinapyl alcohols (Kai et al, 2018). Previously reported by Wei et al (2022), it was found that lignin precursors derived from coniferyl and sinapyl alcohols exhibit strong antibacterial activity against S. aureus.…”

Application of Plasticizer Glycerol in Lignosulfonate-Filled Rubber Compounds Based on SBR and NBR

“…Paracoumaryl alcohol, sinapyl alcohol, and coniferyl alcohol are lignin precursors from which phenyl propane units are formed, namely p-hydroxyphenyl (H), syringyl (S), and guaiacyl (G) units, respectively. The radical copolymerization of these units leads to the formation of lignin polymers [ 3 , 4 , 5 ]. Regarding structure, lignin is an amorphous, highly branched polymer containing ample amounts of functional groups, mostly methoxyl, phenolic, and aliphatic hydroxyl moieties.…”