Polymeric Forms of Plant Flavonoids Obtained by Enzymatic Reactions

Abstract

Naringenin is one of the flavonoids originating from citrus fruit. This polyphenol is mainly found in grapefruit, orange and lemon. The antioxidant and antimicrobial properties of flavonoids depend on their structure, including the polymeric form. The aim of this research was to achieve enzymatic polymerization of naringenin and to study the properties of poly(naringenin). The polymerization was performed by methods using two different enzymes, i.e., laccase and horseradish peroxidase (HRP). According to the literature data, naringenin had not been polymerized previously using the enzymatic polymerization method. Therefore, obtaining polymeric naringenin by reaction with enzymes is a scientific novelty. The research methodology included analysis of the structure of poly(naringenin) by NMR, GPC, FTIR and UV-Vis and its morphology by SEM, as well as analysis of its properties, i.e., thermal stability (DSC and TGA), antioxidant activity (ABTS, DPPH, FRAP and CUPRAC) and antimicrobial properties. Naringenin oligomers were obtained as a result of polymerization with two types of enzymes. The polymeric forms of naringenin were more resistant to thermo-oxidation; the final oxidation temperature To of naringenin catalyzed by laccase (poly(naringenin)-laccase) was 28.2 °C higher, and poly(naringenin)-HRP 23.6 °C higher than that of the basic flavonoid. Additionally, due to the higher molar mass and associated increase in OH groups in the structure, naringenin catalyzed by laccase (poly(naringenin)-laccase) showed better activity for scavenging ABTS+• radicals than naringenin catalyzed by HRP (poly(naringenin)-HRP) and naringenin. In addition, poly(naringenin)-laccase at a concentration of 5 mg/mL exhibited better microbial activity against E. coli than monomeric naringenin.

Effect of enzymatic polymerization on the thermal stability of flavonoids

“…Knowledge of the thermal stability of flavonoids and the changes in their antioxidant activity during heat treatment seems to be important both in the field of food processing [16], as well as in the processing of packaging materials in this industry. Few scientific publications have been devoted to the analysis of the influence of the structure of monomeric flavonoids [16][17][18] and their polymeric forms on their thermal stability, both those occurring in nature and those synthesized in chemical reactions [19][20][21][22][23][24]. Chaaban et al [16] investigated the relationship between thermostability, flavonoid structure and antioxidant activity of six flavonoids (rutin, naringin, eriodictyol, mesquitol, luteolin and luteolin 7-O glucoside).…”

“…The double bond required more energy to degrade [16]. In the case of polymeric flavonoids synthesized as a result of chemical reactions, only a few publications have examined the thermal stability of the compounds obtained [19][20][21][22][23][24]. The relationship between polymeric flavonoids and their thermal properties has been poorly studied.…”

“…The relationship between polymeric flavonoids and their thermal properties has been poorly studied. Polymeric forms of flavonoids have been obtained as a result of several different chemical reactions, such as enzymatic polymerization [20,23,[25][26][27][28][29][30][31][32][33], as well as polymerization with a cross-linking compound [19,21,22,24]. For poly(flavonoids) synthesized by reactions with a cross-linking agent, it was found that the polymeric forms of rutin [21] and quercetin [22], as well as catechin [19] and naringenin [24], had better thermal stability.…”

“…Although enzymatic polymerization is a well-described method of obtaining polymeric forms of flavonoids, and the mechanisms of these reactions are known [20,23,[25][26][27][28][29][30][31][32][33], data on the influence of polymerization on the thermal behaviour of polymeric forms of flavonoids and the relationship of the polymeric structure with these properties are lacking. The authors of these scientific publications focused mainly on characterizing the structure of the polymerization product and determining the antioxidant and antimicrobial properties, as well as finding the SAR for poly(flavonoids) synthesized in enzymatic reactions.…”

Simulate the Dynamic Interactions Across Nutritional Supplements, the Polybiome, and the Biochemical Approach Dependent on Patient-Derived Gastrointestinal Knowledge

“…The drug doesn't enter the bloodstream until after this process is complete. Polymeric flavonoids, for example, arrive in the colon virtually undisturbed in the great majority of instances [9]. Flavonoids and indigestible polymers are exposed to the gut microbiota in the large intestine, where they interact with it to decide their fate [10,11].…”