Polyphenol Polymerization and Antioxidant Properties

Polyphenols are a diverse class of plant-derived compounds characterised by multiple phenolic rings. Owing to their ability to donate electrons or hydrogen atoms, they play a key role in scavenging free radicals and chelating transition metals, thereby mitigating oxidative stress. Polymerization—whether enzymatic, chemical or photochemical—links monomeric polyphenols into oligomers or high-molecular-weight polymers, often altering solubility, redox potential and stability. These structural changes can enhance antioxidant efficacy by increasing the density of phenolic hydroxyl groups and by stabilising resonance-delocalised radicals. Moreover, polymerised forms frequently exhibit superior thermal resistance, controlled release in food and cosmetic formulations, and novel antimicrobial or anticancer activities. Advances in cross-linking chemistry and biocatalysis have enabled tailored polymer architectures, fostering applications in functional materials, nutraceuticals and biomedical devices. By elucidating structure–activity relationships, researchers aim to optimise polymerisation conditions for maximal radical-scavenging capacity without compromising bioavailability or safety.

Research from Nature Portfolio

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Research from all publishers

Researchers have developed a cross-linking strategy to convert monomeric catechin into a polymeric network, producing poly(catechin) with markedly enhanced thermal stability and radical-scavenging capacity. The resultant material resisted oxidation at higher temperatures and demonstrated stronger antibacterial activity against Gram-positive and filamentous fungi compared with its monomer.

Enzymatic polymerization of the flavanone naringenin using grafting agents has yielded poly(naringenin) exhibiting a higher conversion to oligomeric chains. This polymer displayed improved thermal resistance and superior free-radical scavenging in ABTS and DPPH assays, alongside notable antimicrobial effects against bacterial and fungal pathogens, highlighting its potential as a multifunctional additive in eco-friendly polymer composites.

A comparative study of enzymatically produced oligomeric flavonoids employed laccase and peroxidase to polymerise quercetin, rutin and catechin. Analysis by spectroscopic and chromatographic methods revealed that all oligomers possessed elevated oxidation onset temperatures and enthalpies relative to monomers. These oligomeric products also showed enhanced capabilities in metal-reducing assays and improved antimicrobial profiles, underscoring the broad applicability of enzyme-catalysed polymerisation to tailor antioxidant materials.

Polyphenol Polymerization and Antioxidant Properties publication trend

The graph below shows the total number of articles in polyphenol polymerization and antioxidant properties across all publications each year (not limited to Nature Index journals).

Technical terms

Polyphenol: A plant secondary metabolite with multiple phenolic rings, capable of antioxidative activity through radical scavenging and metal chelation.

Polymerization: A chemical or enzymatic process linking monomer units into oligomeric or polymeric chains, modifying physicochemical properties.

Oligomer: A low-molecular-weight polymer composed of a few monomer units, often retaining functional group density for bioactivity.

Proanthocyanidin: A class of oligomeric flavonoids formed by the condensation of flavan-3-ol units, noted for strong antioxidant and health-promoting properties.

Cross-linking agent: A bifunctional or multifunctional compound that covalently bridges monomer units to form polymer networks, enhancing stability and mechanical properties.

References

1. Thermally Stable and Antimicrobial Active Poly(Catechin) Obtained by Reaction with a Cross-Linking Agent. Biomolecules (2020).
2. Novel Polymeric Biomaterial Based on Naringenin. Materials (2021).
3. Polymeric Forms of Plant Flavonoids Obtained by Enzymatic Reactions. Molecules (2022).