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Open AccessArticle

Synthesis and Antiradical Activity of Isoquercitrin Esters with Aromatic Acids and Their Homologues

Laboratory of Biotransformation, Institute of Microbiology, Czech Academy of Sciences, Vídeňská 1083, CZ-142 20 Prague, Czech Republic
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Academic Editor: Yujiro Hayashi
Int. J. Mol. Sci. 2017, 18(5), 1074; https://doi.org/10.3390/ijms18051074
Received: 27 April 2017 / Revised: 12 May 2017 / Accepted: 13 May 2017 / Published: 17 May 2017
(This article belongs to the Special Issue Molecular Transformations of Natural Products)
Isoquercitrin, (IQ, quercetin-3-O-β-d-glucopyranoside) is known for strong chemoprotectant activities. Acylation of flavonoid glucosides with carboxylic acids containing an aromatic ring brings entirely new properties to these compounds. Here, we describe the chemical and enzymatic synthesis of a series of IQ derivatives at the C-6″. IQ benzoate, phenylacetate, phenylpropanoate and cinnamate were prepared from respective vinyl esters using Novozym 435 (Lipase B from Candida antarctica immobilized on acrylic resin). The enzymatic procedure gave no products with “hydroxyaromatic” acids, their vinyl esters nor with their benzyl-protected forms. A chemical protection/deprotection method using Steglich reaction yielded IQ 4-hydroxybenzoate, vanillate and gallate. In case of p-coumaric, caffeic, and ferulic acid, the deprotection lead to the saturation of the double bonds at the phenylpropanoic moiety and yielded 4-hydroxy-, 3,4-dihydroxy- and 3-methoxy-4-hydroxy-phenylpropanoates. Reducing capacity of the cinnamate, gallate and 4-hydroxyphenylpropanoate towards Folin-Ciocalteau reagent was significantly lower than that of IQ, while other derivatives displayed slightly better or comparable capacity. Compared to isoquercitrin, most derivatives were less active in 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, but they showed significantly better 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid, ABTS) scavenging activity and were substantially more active in the inhibition of tert-butylhydroperoxide induced lipid peroxidation of rat liver microsomes. The most active compounds were the hydroxyphenylpropanoates. View Full-Text
Keywords: isoquercitrin; aromatic acid; gallic acid; cinnamic acid; antioxidant activity; Novozym 435; lipase; DPPH; lipoperoxidation isoquercitrin; aromatic acid; gallic acid; cinnamic acid; antioxidant activity; Novozym 435; lipase; DPPH; lipoperoxidation
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MDPI and ACS Style

Heřmánková-Vavříková, E.; Křenková, A.; Petrásková, L.; Chambers, C.S.; Zápal, J.; Kuzma, M.; Valentová, K.; Křen, V. Synthesis and Antiradical Activity of Isoquercitrin Esters with Aromatic Acids and Their Homologues. Int. J. Mol. Sci. 2017, 18, 1074.

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