Improved enzyme-mediated synthesis and supramolecular self-assembly of naturally occurring conjugates of beta-sitosterol

Naturally occurring acylated beta-sitostetyl glucosides have been investigated for their novel properties. The synthetic protocol based on the literature data was improved and optimized. The main improveinent consists in employing systems of ionic liquids combined with organic solvents in lipase-med...

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Bibliographic Details
Published in:Steroids
Main Authors: Wimmerová, M. (Martina), Siglerová, V. (Věra), Šaman, D. (David), Šlouf, M. (Miroslav), Kaletová, E. (Eva), Wimmer, Z. (Zdeněk)
Format: Article in Journal/Newspaper
Language:English
Published: 2017
Subjects:
glycosides
esterification
resolution
sterols
esters
foods
l
beta-Sitosterol
Acylated steryl glycoside
Lipase
Ionic liquid
Supramolecular self-assembly
Pharmacological activity
Antarc*
Antarctica
Online Access:https://doi.org/10.1016/j.steroids.2016.09.009
http://hdl.handle.net/11104/0271064
Description
Summary:Naturally occurring acylated beta-sitostetyl glucosides have been investigated for their novel properties. The synthetic protocol based on the literature data was improved and optimized. The main improveinent consists in employing systems of ionic liquids combined with organic solvents in lipase-mediated esterification of (3 beta)-stigmast-5-en-3-yl beta-D-glucopyranoside to get (3 beta)-stigmast-5-en-3-yl 6-O-acyl-beta-D-glucopyranosides. Maximum yields of these products were achieved with Candida antarctica lipase B immobilized on Immobead 150, recombinant from yeast, in absolute THE and in the presence of either ionic liquid [1-butyl-3-methyl imidazolium tetrafluoroborate ([BMIM]BF4) or 1-butyl-3-methyl imidazolium hexafluorophosphate ([BMIM]PF6)] employed. Pharmacological activity of (3 beta)-stigmast-5-en3-yl 6-O-acyl-beta-D-glucopyranosides was studied in tests on MCF7 tumor cell lines, the compounds displayed moderate activity which was higher than the activity of B-sitosterol. Supramolecular characteristics were discovered at (3 beta)-stigmast-5-en-3-yl 6-O-dodecanoyl-beta-D-glucopyranoside that formed supramolecular polymer through multiple H-bonds in a methanol/water system (60/40). Its formation was confirmed by the independent UV-vis measurements during certain time period, by variable temperature DOSY-NMR measurement in deuteriochloroform, and visualized by transmission electron microscopy (TEM) and atomic force microscopy (AFM) showing chiral helical structures and complex superassembly systems based on fibrous supramolecular polymer. In contrary, no such properties have been observed for the other two (3 beta)-stigmast-5-en-3-yl 6-O-acyl-beta-D-glucopyranosides under the given experimental conditions.

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