Flavonoids and their glycosides are abundant in many plant-based foods. The (de)glycosylation of flavonoids by retaining glycoside hydrolases has recently attracted much interest in basic and applied research, including the possibility of altering the glycosylation pattern of flavonoids. Research in this area is driven by significant differences in physicochemical, organoleptic, and bioactive properties between flavonoid aglycones and their glycosylated counterparts. While many flavonoid glycosides are present in nature at low levels, some occur in substantial quantities, making them readily available low-cost glycosyl donors for transglycosylations. Retaining glycosidases can be used to synthesize natural and novel glycosides, which serve as standards for bioactivity experiments and analyses, using flavonoid glycosides as glycosyl donors. Engineered glycosidases also prove valuable for the synthesis of flavonoid glycosides using chemically synthesized activated glycosyl donors. This review outlines the bioactivities of flavonoids and their glycosides and highlights the applications of retaining glycosidases in the context of flavonoid glycosides, acting as substrates, products, or glycosyl donors in deglycosylation or transglycosylation reactions.

• Klíčová slova
• Glucosidase, Glycoside hydrolase, Glycosyl donor, Glycosynthase, Hydrolysis, Rutinosidase, Transglycosylation,
• MeSH
• flavonoidy * chemie   MeSH
• glykosidhydrolasy * metabolismus   MeSH
• glykosidy chemie   MeSH
• glykosylace MeSH
• katalýza MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• flavonoidy * MeSH
• glykosidhydrolasy * MeSH
• glykosidy MeSH

This study aimed to examine the effect of dietary flavonoid isoquercitrin on ovarian granulosa cells using the immortalized human cell line HGL5. Cell viability, survival, apoptosis, release of steroid hormones 17beta-estradiol and progesterone, and human transforming growth factor-beta2 (TGF-beta2) and TGF-beta2 receptor as well as intracellular reactive oxygen species (ROS) generation were investigated after isoquercitrin treatment at the concentration range of 5-100 microg.ml-1. It did not cause any significant change (p>0.05) in cell viability as studied by AlamarBlue assay in comparison to control. No significant change was observed (p>0.05) in the proportion of live, dead and apoptotic cells as revealed by apoptotic assay using flow cytometry. Similarly, the release of 17beta-estradiol, progesterone, TGF-beta2 and its receptor were not affected significantly (p>0.05) by isoquercitrin as detected by ELISA, in comparison to control. Except for the highest concentration of 100 microg.ml-1, which led to oxidative stress, isoquercitrin exhibited antioxidative activity at lower concentration used in the study (5, 10, 25, and 50 microg.ml-1) by hampering the production of intracellular ROS, in comparison to control, as detected by chemiluminescence assay (p<0.05). Findings of the present study indicate an existence of the antioxidative pathway that involves inhibition of intracellular ROS generation by isoquercitrin in human ovarian granulosa cells.

• MeSH
• buněčné linie MeSH
• folikulární buňky účinky léků   metabolismus   MeSH
• lidé MeSH
• quercetin aplikace a dávkování   analogy a deriváty   MeSH
• reaktivní formy kyslíku metabolismus   MeSH
• Check Tag
• lidé MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• isoquercitrin MeSH Prohlížeč
• quercetin MeSH
• reaktivní formy kyslíku MeSH

Quercetin is a flavonoid largely employed as a phytochemical remedy and a food or dietary supplement. We present here a novel biocatalytic methodology for the preparation of quercetin from plant-derived rutin, with both substrate and product being in mostly an undissolved state during biotransformation. This "solid-state" enzymatic conversion uses a crude enzyme preparation of recombinant rutinosidase from Aspergillus niger yielding quercetin, which precipitates from virtually insoluble rutin. The process is easily scalable and exhibits an extremely high space-time yield. The procedure has been shown to be robust and was successfully tested with rutin concentrations of up to 300 g/L (ca 0.5 M) at various scales. Using this procedure, pure quercetin is easily obtained by mere filtration of the reaction mixture, followed by washing and drying of the filter cake. Neither co-solvents nor toxic chemicals are used, thus the process can be considered environmentally friendly and the product of "bio-quality." Moreover, rare disaccharide rutinose is obtained from the filtrate at a preparatory scale as a valuable side product. These results demonstrate for the first time the efficiency of the "Solid-State-Catalysis" concept, which is applicable virtually for any biotransformation involving substrates and products of low water solubility.

• Klíčová slova
• Aspergillus niger, quercetin, rutin, rutinose, rutinosidase, “solid-state biocatalysis”,
• MeSH
• Aspergillus niger enzymologie   genetika   MeSH
• biokatalýza * MeSH
• disacharidy chemie   metabolismus   MeSH
• fungální proteiny genetika   metabolismus   MeSH
• glykosidhydrolasy genetika   metabolismus   MeSH
• Pichia genetika   metabolismus   MeSH
• průmyslová mikrobiologie metody   MeSH
• quercetin chemie   metabolismus   MeSH
• rutin chemie   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• beta-rutinosidase MeSH Prohlížeč
• disacharidy MeSH
• fungální proteiny MeSH
• glykosidhydrolasy MeSH
• quercetin MeSH
• rutin MeSH
• rutinose MeSH Prohlížeč

Natural flavonoids, especially in their glycosylated forms, are the most abundant phenolic compounds found in plants, fruit, and vegetables. They exhibit a large variety of beneficial physiological effects, which makes them generally interesting in a broad spectrum of scientific areas. In this review, we focus on recent advances in the modifications of the glycosidic parts of various flavonoids employing glycosidases, covering both selective trimming of the sugar moieties and glycosylation of flavonoid aglycones by natural and mutant glycosidases. Glycosylation of flavonoids strongly enhances their water solubility and thus increases their bioavailability. Antioxidant and most biological activities are usually less pronounced in glycosides, but some specific bioactivities are enhanced. The presence of l-rhamnose (6-deoxy-α-l-mannopyranose) in rhamnosides, rutinosides (rutin, hesperidin) and neohesperidosides (naringin) plays an important role in properties of flavonoid glycosides, which can be considered as "pro-drugs". The natural hydrolytic activity of glycosidases is widely employed in biotechnological deglycosylation processes producing respective aglycones or partially deglycosylated flavonoids. Moreover, deglycosylation is quite commonly used in the food industry aiming at the improvement of sensoric properties of beverages such as debittering of citrus juices or enhancement of wine aromas. Therefore, natural and mutant glycosidases are excellent tools for modifications of flavonoid glycosides.

• Klíčová slova
• catechin, enzymatic hydrolysis, hesperetin, icariin, naringenin, puerarin, quercetin, rhamnosidase, rutinosidase, transglycosylation,
• MeSH
• flavonoidy metabolismus   MeSH
• glykosidhydrolasy metabolismus   MeSH
• isoflavony metabolismus   MeSH
• katechin metabolismus   MeSH
• lidé MeSH
• quercetin metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• flavonoidy MeSH
• glykosidhydrolasy MeSH
• isoflavony MeSH
• katechin MeSH
• puerarin MeSH Prohlížeč
• quercetin MeSH

Interaction of flavonoids with transition metals can be partially responsible for their impact on humans. Stoichiometry of the iron/copper complex with a flavonoid glycoside isoquercitrin, a frequent component of food supplements, was assessed using competitive and non-competitive methods in four (patho)physiologically-relevant pH values (4.5. 5.5, 6.8, and 7.5). Isoquercitrin chelated all tested ions (Fe2+, Fe3+, Cu2+, and Cu⁺) but its affinity for Cu⁺ ions proved to be very low. In general, the chelation potency dropped with pH lowering. Metal complexes of 1:1 stoichiometry were mostly formed, however, they were not stable and the stoichiometry changed depending on conditions. Isoquercitrin was able to reduce both Cu2+ and Fe3+ ions at low ratios, but its reducing potential was diminished at higher ratios (isoquercitrin to metal) due to the metal chelation. In conclusion, this study emphasizes the need of using multiple different methods for the assessment of chelation potential in moderately-active metal chelators, like flavonoids.

• Klíčová slova
• Job’s method, chelator, copper, iron, quercetin-3-O-β-glucopyranoside, reduction, stoichiometry,
• MeSH
• chelátory chemie   MeSH
• flavonoidy chemie   MeSH
• koncentrace vodíkových iontů MeSH
• měď chemie   MeSH
• quercetin analogy a deriváty   chemie   MeSH
• železo chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• chelátory MeSH
• flavonoidy MeSH
• isoquercitrin MeSH Prohlížeč
• měď MeSH
• quercetin MeSH
• železo MeSH

Sulfated quercetin derivatives are important authentic standards for metabolic studies. Quercetin-3'-O-sulfate, quercetin-4'-O-sulfate, and quercetin-3-O-sulfate as well as quercetin-di-O-sulfate mixture (quercetin-7,3'-di-O-sulfate, quercetin-7,4'-di-O-sulfate, and quercetin-3',4'-di-O-sulfate) were synthetized by arylsulfotransferase from Desulfitobacterium hafniense. Purified monosulfates and disulfates were fully characterized using MS and NMR and tested for their 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS⁺) and N,N-dimethyl-p-phenylenediamine (DMPD) radical scavenging, Folin-Ciocalteau reduction (FCR), ferric reducing antioxidant power (FRAP), and anti-lipoperoxidant activities in rat liver microsomes damaged by tert-butylhydroperoxide. Although, as expected, the sulfated metabolites were usually less active than quercetin, they remained still effective antiradical and reducing agents. Quercetin-3'-O-sulfate was more efficient than quercetin-4'-O-sulfate in DPPH and FCR assays. In contrast, quercetin-4'-O-sulfate was the best ferric reductant and lipoperoxidation inhibitor. The capacity to scavenge ABTS+• and DMPD was comparable for all substances, except for disulfates, which were the most efficient. Quantum calculations and molecular dynamics simulations on membrane models supported rationalization of free radical scavenging and lipid peroxidation inhibition. These results clearly showed that individual metabolites of food bioactives can markedly differ in their biological activity. Therefore, a systematic and thorough investigation of all bioavailable metabolites with respect to native compounds is needed when evaluating food health benefits.

• Klíčová slova
• antiradical activity, density functional theory, lipid peroxidation, metabolites, molecular dynamics, quercetin, sulfates, sulfotransferase,
• MeSH
• antioxidancia MeSH
• arylsulfotransferasa metabolismus   MeSH
• Desulfitobacterium enzymologie   MeSH
• quercetin analogy a deriváty   analýza   chemická syntéza   metabolismus   MeSH
• sírany analýza   chemická syntéza   metabolismus   MeSH
• vztahy mezi strukturou a aktivitou MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antioxidancia MeSH
• arylsulfotransferasa MeSH
• quercetin 3'-sulfate MeSH Prohlížeč
• quercetin MeSH
• sírany MeSH

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.

• Klíčová slova
• DPPH, Novozym 435, antioxidant activity, aromatic acid, cinnamic acid, gallic acid, isoquercitrin, lipase, lipoperoxidation,
• MeSH
• estery * chemie   MeSH
• hmotnostní spektrometrie MeSH
• molekulární struktura MeSH
• nukleární magnetická rezonance biomolekulární MeSH
• peroxidace lipidů účinky léků   MeSH
• quercetin analogy a deriváty   analýza   chemická syntéza   farmakologie   MeSH
• scavengery volných radikálů analýza   chemická syntéza   farmakologie   MeSH
• vysokoúčinná kapalinová chromatografie MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• estery * MeSH
• isoquercitrin MeSH Prohlížeč
• quercetin MeSH
• scavengery volných radikálů MeSH

A series of isoquercitrin (quercetin-3-O-β-d-glucopyranoside) esters with mono- or dicarboxylic acids was designed to modulate hydro- and lipophilicity and biological properties. Esterification of isoquercitrin was accomplished by direct chemoenzymatic reaction using Novozym 435 (lipase from Candida antarctica), which accepted C₅- to C12-dicarboxylic acids; the shorter ones, such as oxalic (C₂), malonic (C₃), succinic (C₄) and maleic (C₄) acids were not substrates of the lipase. Lipophilicity of monocarboxylic acid derivatives, measured as log P, increased with the chain length. Esters with glutaric and adipic acids exhibited hydrophilicity, and the dodecanedioic acid hemiester was more lipophilic. All derivatives were less able to reduce Folin-Ciocalteau reagent (FCR) and scavenge DPPH (1,1-diphenyl-2-picrylhydrazyl) than isoquercitrin; ABTS (2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)) radical-scavenging activity was comparable. Dodecanoate and palmitate were the least active in FCR and ABTS scavenging; dodecanoate and hemiglutarate were the strongest DPPH scavengers. In contrast, most derivatives were much better inhibitors of microsomal lipoperoxidation than isoquercitrin; butyrate and hexanoate were the most efficient. Anti-lipoperoxidant activity of monocarboxylic derivatives, except acetates, decreased with increasing aliphatic chain. The opposite trend was noted for dicarboxylic acid hemiesters, isoquercitrin hemidodecanedioate being the most active. Overall, IQ butyrate, hexanoate and hemidodecanedioate are the most promising candidates for further studies.

• Klíčová slova
• DPPH, Novozym 435, antioxidant activity, fatty acid, isoquercitrin, lipase, lipoperoxidation, log P, quercetin,
• MeSH
• antioxidancia chemická syntéza   chemie   farmakologie   MeSH
• estery chemická syntéza   chemie   farmakologie   MeSH
• katalýza MeSH
• kyseliny dikarboxylové chemie   MeSH
• kyseliny karboxylové chemie   MeSH
• molekulární struktura MeSH
• protonová magnetická rezonanční spektroskopie MeSH
• quercetin analogy a deriváty   chemická syntéza   chemie   farmakologie   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antioxidancia MeSH
• estery MeSH
• isoquercitrin MeSH Prohlížeč
• kyseliny dikarboxylové MeSH
• kyseliny karboxylové MeSH
• quercetin MeSH