Enzymatic Conversion of Oleuropein to Hydroxytyrosol Using Immobilized <i>β</i>-Glucosidase on Porous Carbon Cuboids

• Main Authors: Alexandra V. Chatzikonstantinou, Elena Gkantzou, Eleni Thomou, Nikolaos Chalmpes, Kyriaki-Marina Lyra, Vasiliki G. Kontogianni, Konstantinos Spyrou, Michaela Patila, Dimitrios Gournis, Haralambos Stamatis
• Format: Article
• Language: English
• Published: MDPI AG 2019-08-01
• Series: Nanomaterials
• Subjects: <i>β</i>-glucosidase; carbon cuboids; hydroxytyrosol; oleuropein; bio-catalysis; nano-biocatalyst
• Online Access: https://www.mdpi.com/2079-4991/9/8/1166

In the present study, we developed novel <i>&#946;</i>-glucosidase-based nano-biocatalysts for the bioconversion of oleuropein to hydroxytyrosol. Using non-covalent or covalent immobilization approaches, <i>&#946;</i>-glucosidases from almonds and <i>Thermotoga maritima</i> were attached for the first time on oxidized and non-oxidized porous carbon cuboids (PCC). Various methods were used for the characterization of the bio-nanoconjugates, such as Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and fluorescence spectroscopy. The oxidation state of the nan&#959;-support and the immobilization procedure play a key role for the immobilization efficiency or the catalytic activity of the immobilized <i>&#946;</i>-glucosidases. The nano-biocatalysts were successfully used for the hydrolysis of oleuropein, which leads to the formation of its bioactive derivative, hydroxytyrosol (up to 2.4 g L^&#8722;1), which is a phenolic compound with numerous health benefits. The bio-nanoconjugates exhibited high thermal and operational stability (up to 240 h of repeated use), which indicated that they are efficient tools for various bio-transformations.