Transrutinosylation of tyrosol by flower buds of Sophora japonica

Article abstract of DOI:10.1016/j.foodchem.2020.127674

Dried flower buds of Japanese sophora (Sophora japonica) comprising rutinosidase activity were tested in rutinosylation of tyrosol via transglycosylation process from rutin. Optimal conditions for transrutinosylation of tyrosol were 49 mM rutin and 290 mM

Full text of DOI:10.1016/j.foodchem.2020.127674

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Transrutinosylation of tyrosol by flower buds of Sophora japonica
Elena Karnišová Potocká, Mária Mastihubová, Vladimír Mastihuba
Conceptuation
PII:
S0308-8146(20)31536-3
DOI:
Reference:
https://doi.org/10.1016/j.foodchem.2020.127674
FOCH 127674
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Food Chemistry
Received Date:
Revised Date:
Accepted Date:
14 February 2020
20 July 2020
23 July 2020
Please cite this article as: Karnišová Potocká, E., Mastihubová, M., Mastihuba Conceptuation, V.,
Transrutinosylation of tyrosol by flower buds of Sophora japonica, Food Chemistry (2020), doi: https://doi.org/
10.1016/j.foodchem.2020.127674
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Transrutinosylation of tyrosol by flower buds of Sophora japonica
Elena Karnišová Potocká, Mária Mastihubová, Vladimír Mastihuba*
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Institute of Chemistry, Slovak Academy of Sciences,
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Dúbravská cesta 9, SK-845 38 Bratislava, Slovakia, vladimir.mastihuba@savba.sk
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Abstract
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Dried flower buds of Japanese sophora (Sophora japonica) comprising rutinosidase
activity were tested in rutinosylation of tyrosol via transglycosylation process from rutin.
Optimal conditions for transrutinosylation of tyrosol were 49 mM rutin and 290 mM tyrosol,
giving maximum conversion up to 66.4 % and 24 % yield of isolated and purified
rutinoside. The rutinosylation proceeded exclusively on the primary hydroxyl of tyrosol,
thus forming rhamnosylated derivative of salidroside. This strict regioselectivity
differentiates the sophora biocatalyst from microbial rutinosidases.
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Keywords: rutinosidase; rutin, Sophora japonica; tyrosol rutinoside; transglycosylation
1. Introduction
Tyrosol and hydroxytyrosol are low-molecular phenolic antioxidants occurring in olive oil
and in by-products from olive production and processing (Wani et al., 2018; Conde, Cara,
Moure, Ruiz, Castro & Domínguez, 2009). Their esters may find use in stabilization of
lipids and emulsions (Sun, Zhou & Shahidi, 2018; Akanbi & Barrow, 2018), while
glycosides of tyrosol and hydroxytyrosol display wide spectra of pharmacological activities
including anticancer (Sun, Wang, Zheng & Zhang, 2012), antiviral (Wang, Ding, Zhou, Sun
& Wang, 2009), antiinflammatory (Guan et al., 2011), antidiabetic (Li, Ge, Zheng & Zhang,
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2008), neuroprotective (Nieto-Dominguez et al., 2017), cardioprotective (Liang et al. 2010,
Zhang et al. 2009) and hepatoprotective (Wu, Lian, Jiang & Nan, 2009).
Enzymatic glycosylations catalyzed by glycosidases offer an effective, straightforward
and environmentally friendly alternative to rather complicated and oftentimes harmful
chemical procedures. Generally, two methods may be employed in one-step enzymatic
preparation of glycosides catalyzed by glycosidases – transglycosylation and reversed
hydrolysis. Reversed hydrolysis is a thermodynamic process leading to equilibrium
between the target glycoside and starting monosaccharide while transglycosylation
employs partial transferase activity of glycosidases. Glycosidase thus catalyzes the
transfer of monosaccharide from the nonreducing end of the substrate (polysaccharide,
oligosaccharide, or glycoside) to a nucleophil (an alcohol or another molecule of the
saccharide) present in the reaction mixture (van Rantwijk, Woudenberg-van Oosterom &
Sheldon 1999). The presence of transferase activity is limited to retaining glycosidases
and its displayed level in particular enzyme varies depending on its origin and reaction
conditions.
Within our research on enzymatic syntheses of natural tyrosol glycosides and their new
derivatives, we have recently prepared salidroside (tyrosol β-D-glucopyranoside) and its α-
and β-D-galacto- and β-fructofurano- analogues by use of microbial enzymes (Potocká,
Mastihubová & Mastihuba, 2015; Karnišová Potocká, Mastihubová & Mastihuba, 2019).
Enzymatic synthesis of salidroside by reversed hydrolysis is a well studied process,
employing usually plant β-glucosidases (Bi et al., 2012) Recently published enzymatic
preparations of pure glycosides of tyrosol and hydroxytyrosol such as β-glucosides
(Méndez-Líter et. al., 2019), β-galactosides (Qi, Gu, Xu, Xiao & Lu, 2017), β-
fructofuranosides (Míguez et. al., 2018) and β-xylopyranosides (Nieto-Dominguez et al.,
2017) rely however on the more advantageous transglycosylation process.
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To extend the scale of glycosides of tyrosol for studies of their acylations toward natural
pharmacologically active substances, we focused on preparation of a structured
oligoglycoside of tyrosol, namely 2-(4-hydroxyphenyl)ethyl β-rutinoside (TR1), which would
be free of its structural analogue TR2 (Figure 1).
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Figure 1. Structure of isomers of tyrosol β-rutinosides.
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Kinetically controlled transrhamnosylation of the corresponding glucoside, salidroside, is
not possible due to the inverting mechanism of α-L-rhamnosidases and these enzymes
can therefore produce rutinosides only through reversed rhamnosylation. In addition to the
obvious problems of the reversed hydrolysis of glycosides (long reaction times, low
chemical yields), the price of rhamnose used in high starting concentration makes the
reversed rhamnosylation rather unpractical. A more convenient way how to obtain TR1
may be use of rutinosidase for direct rutinosylation of tyrosol. Rutinosidases (EC
3.2.1.168) belong to a special group of β-glycosidases, so-called diglycosidases, which are
specific to hydrolysis of diglycosides comprising β-D-glucose on the reducing end of the
glycone.
Diglycosidases
(rutinosidases,
acuminosidases,
vicianosidases,
primeverosidases) occur more typically in plant tissues, although they can be produced by
microorganisms as well. Their main role in the plant kingdom is an immediate hydrolysis of
diglycosides (such as cyanogenic or terpenyl glycosides) and fast liberation of toxic or
semiotic aglycones in one-step mechanism (Mizutani et al., 2002). Rutinosidases can be
found among plants and some filamentous fungi. They hydrolyze rutinosides like rutin and
hesperidin into rutinose and the corresponding aglycone. Some rutinosidases were found
to be able to perform also the transrutinosylation reactions, which means that they do not
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