Laccase Activity as an Essential Factor in the Oligomerization of Rutin

Abel Muñiz-Mouro,Juan Lema,Gemma Eibes,María Moreira,Beatriz Gullón,Thelmo Lú-Chau

doi:10.3390/catal8080321

Abel Muñiz-Mouro, Juan Lema + Show 4 more

Open Access

https://doi.org/10.3390/catal8080321

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Abstract

The enzyme-mediated polymerization of bioactive phenolic compounds, such as the flavonoid rutin, has gained interest due to the enhanced physico-chemical and biological properties of the products, which increases their potential application as a nutraceutical. In this work, the influence of enzyme activity on rutin oligomerization was evaluated in reactions with low (1000 U/L) and high (10,000 U/L) initial laccase activities. For both reactions, high molecular weight oligomer fractions showed better properties compared to lower weight oligomers. Products of the reaction with low laccase activity exhibited thermal stability and antioxidant potential similar to control reaction, but led to higher inhibitory activity of xanthine oxidase and apparent aqueous solubility. Oligomers obtained in the reaction with high laccase activity showed better apparent aqueous solubility but decreased biological activities and stability. Their low antioxidant activity was correlated with a decreased phenolic content, which could be attributed to the formation of several bonds between rutin molecules.

Highlights

Flavonoids are one of the main types of polyphenols commonly identified in plants as secondary metabolites [1]
The results provided by the Folin–Ciocalteu assay showed a slight loss of reducing phenolic compounds (RPC) for AF3 of less than 15% compared to coniferyl alcohol (CA), indicating that O–C bonding could have occurred
The rutin oligomers with the best characteristics for its use as a nutraceutical were obtained in the reaction with the lowest laccase activity (1000 U/L)

Summary

Introduction

Flavonoids are one of the main types of polyphenols commonly identified in plants as secondary metabolites [1] This type of compound exhibits satisfactory antioxidant capacities [2,3] and pharmacological properties, with potential use in the prevention of various diseases such as diabetes, cancer, cardiovascular, and neurodegenerative diseases [4,5]. Due to its useful properties, the Dietary Supplement Label Database lists over 1100 currently marketed products that contain rutin [8]. Both its low solubility in aqueous and non-toxic organic solvents, which imply scarce bioavailability, and poor thermal stability [9,10,11], restrict its application. Enzymatic polymerization of polyphenolic monomers has been shown to produce higher molecular weight polyphenols with improved solubility, thermostability, and superior antioxidant properties [12,13,14,15,16]

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