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The modification of gum Arabic with ferulic acid oxidation products was performed in aqueous medium, at 30 °C and pH 7.5, in the presence of Myceliophthora thermophila laccase as biocatalyst. First, this study aimed to investigate the structures of the oxidation products of ferulic acid that could possibly be covalently grafted onto gum Arabic. HPLC analyses revealed that this reaction produced several oxidation products, whose structures were investigated using LC-MS/MS analyses (liquid chromatography-mass spectrometry with mass fragmentation analyses) and NMR experiments. The chemical structure of one intermediate reaction product was fully elucidated as the 2-(4-hydroxy-3-methoxyphenyl)-4-[(4-hydroxy-3-methoxyphenyl) methylidene] cyclobutane-1, 3-dione, called by the authors cyclobutadiferulone. Secondly, this study aimed to locate the grafting of the oxidation products onto gum Arabic by performing several NMR experiments. This study did not determine how much and specifically which oxidation products were grafted but some of them were undeniably present onto modified gum Arabic, close to the glucuronic acid C5 carbon or close to the galactose C6 carbon., Competing Interests: Declaration of competing interest The authors declare no competing financial interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Carnosine (CAR) dipeptide was functionalized with ferulic acid (FA) as substrate using laccase from Myceliophtora thermophila as biocatalyst. The enzymatic reaction was performed in aqueous medium under mild conditions (pH 7.5, 30°C) as an eco-friendly procedure. Results showed that this enzymatic process led to the synthesis of two new derivatives (P1, P2), from the coupling between CAR and FA derived products. Conditions allowing a high production of P1, P2 derivatives were determined with an optimal ratio of (FA: CAR) of (1:1.6) at optimal time reaction of 8h. Under these optimal conditions, the coupling between CAR and FA-products was demonstrated, resulting in the decrease of -NH2 groups (almost 50%) as quantified via derivatization. Due to the presence of FA in the structure of these new derivatives, they exhibited higher hydrophobic property than carnosine. Structural analyses by mass spectrometry showed that P1 and P2 (FA-CAR) derivatives exhibited the same molecular mass (MM 770g/mol) containing one CAR-molecule and three FA-molecules but with different chemical structures. Furthermore, these derivatives presented improved antioxidant (almost 10 times) and anti-proliferative (almost 18 times) properties in comparison with CAR. Moreover, P1 derivative exhibited higher antioxidant and anti-proliferative activities than P2 derivative, which confirmed the different structures of P1 and P2. These results suggested that the oxidized phenols coupling with carnosine is a promising process to enhance the CAR-properties., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The enzymatic oxidation of ferulic acid (FA) and ethyl ferulate (EF) with Myceliophthora thermophila laccase, as biocatalyst, was performed in aqueous medium using an eco-friendly procedure to synthesize new active molecules. First, the commercial laccase was ultrafiltrated allowing for the elimination of phenolic contaminants and increasing the specific activity by a factor of 2. Then, kinetic parameters of this laccase were determined for both substrates (FA, EF), indicating a higher substrate affinity for ethyl ferulate. Additionally, enzymatic oxidation led to the synthesis of a FA-major product, exhibiting a molecular mass of 386 g/mol and a EF-major product with a molecular mass of 442 g/mol. Structural analyses by mass spectrometry allowed the identification of dimeric derivatives. The optical properties of the oxidation products showed the increase of red and yellow colours, with FA-products compared to EF-products. Additionally, enzymatic oxidation led to a decrease of antioxidant and cytotoxic activities compared to initial substrates. Consequently, this enzymatic procedure in aqueous medium could provide new compounds presenting optical, antioxidant and cytotoxic interest., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

The ferulic acid (FA)-oxidation by Myceliophthora thermophila laccase was performed in phosphate buffer at 30 °C and pH 7.5 as an eco-friendly procedure. LC-MS analysis showed that oxidation products were four dehydrodimers (P1, P2, P3, P5) at MM = 386 g/mol, two dehydrotetramers (P6, P7) at MM = 770 g/mol and one decarboxylated dehydrodimer (P4) at MM = 340 g/mol. Structural characterization showed that FA-dehydrodimers were symmetric for P1 and P5 while asymmetric for P2, P3 and P4. Physicochemical characterization showed that oxidation products presented a higher lipophilicity than that of FA. Moreover, symmetric dimers and tetra dimers had a higher melting point compared to FA and its asymmetric dimers. Antioxidant and anti-proliferative assessments indicated that enzymatic oligomerization increased antioxidant and anti-proliferative properties of oxidation products for P2, P3 and P6 compared to FA. Finally, this enzymatic process in water could produce new molecules, having good antiradical and anti-proliferative activities. [ABSTRACT FROM AUTHOR]