- Two new acetylated flavonoid glycosides from Phyllanthus urinaria
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Two new acetylated flavonoid glycosides, quercetin 3-O-α-l-(2,4-di-O- acetyl) rhamnopyranoside-7-O-α-l-rhamnopyranoside (1) and quercetin 3-O-α-l-(3,4-di-O-acetyl) rhamnopyranoside-7-O-α-l-rhamnopyranoside (2), together with two known compounds, quercetin
- Wu, Chun,Wei, Chun-Shan,Yu, Shao-Fu,Liu, Bai-Lian,Li, Yao-Lan,Ye, Wen-Cai,Tong, Guang-Dong,Zhou, Guang-Xiong
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- FLAVONOID GLYCOSIDES AND AN ANTHRAQUINONE FROM RUMEX CHALEPENSIS
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Besides rutin, quercetin 3-rhamnoside and kaempferol 3-rhamnosyl (1-4)galactoside, and 1,6,8-trihydroxy-1-methyl anthraquinone (emodine) have been characterized from leaves of Rumex chalepensis.The structures were established on the basis of Rf values, acid hydrolysis to aglycone and sugar and UV, EI and FAB-mass-spectra, 1H NMR, 12C DEPT NMR, NOE difference measurements, 1H-H-COSY and 1H-13C COSY spectral data.
- Hasan, Aurangzeb,Ahmed, Iftikar,Jay, Maurice,Voirin, Bernard
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- Mechanistically elucidating the in vitro safety and efficacy of a novel doxorubicin derivative
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Doxorubicin is an effective anticancer drug; however, it is cardiotoxic and has poor oral bioavazilability. Quercetin is a plant-based flavonoid with inhibitory effects on P-glycoprotein (P-gp) and CYP3A4 and also antioxidant properties. To mitigate these therapeutic barriers, DoxQ, a novel derivative of doxorubicin, was synthesized by conjugating quercetin to doxorubicin. The purpose of this study is to mechanistically elucidate the in vitro safety and efficacy of DoxQ. Drug release in vitro and cellular uptake by multidrug-resistant canine kidney (MDCK-MDR) cells were quantified by HPLC. Antioxidant activity, CYP3A4 inhibition, and P-gp inhibitory effects were examined using commercial assay kits. Drug potency was assessed utilizing triple-negative murine breast cancer cells, and cardiotoxicity was assessed utilizing adult rat and human cardiomyocytes (RL-14). Levels of reactive oxygen species and gene expression of cardiotoxicity markers, oxidative stress markers, and CYP1B1 were determined in RL-14. DoxQ was less cytotoxic to both rat and human cardiomyocytes and retained anticancer activity. Levels of ROS and markers of oxidative stress demonstrate lower oxidative damage induced by DoxQ compared to doxorubicin. DoxQ also inhibited the expression and catalytic activity of CYP1B1. Additionally, DoxQ inhibited CYP3A4 and demonstrated higher cellular uptake by MDCK-MDR cells than doxorubicin. DoxQ provides a novel therapeutic approach to mitigate the cardiotoxicity and poor oral bioavailability of doxorubicin. The cardioprotective mechanism of DoxQ likely involves scavenging ROS and CYP1B1 inhibition, while the mechanism of improving the poor oral bioavailability of doxorubicin is likely related to inhibiting CYP3A4 and P-gp.
- Alrushaid, Samaa,Zhao, Yunqi,Sayre, Casey L.,Maayah, Zaid H.,Laird Forrest,Senadheera, Sanjeewa N.,Chaboyer, Kevin,Anderson, Hope D.,El-Kadi, Ayman O. S.,Davies, Neal M.
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- Exploring the oxidation and iron binding profile of a cyclodextrin encapsulated quercetin complex unveiled a controlled complex dissociation through a chemical stimulus
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Background: Flavonoids possess a rich polypharmacological profile and their biological role is linked to their oxidation state protecting DNA from oxidative stress damage. However, their bioavailability is hampered due to their poor aqueous solubility. This can be surpassed through encapsulation to supramolecular carriers as cyclodextrin (CD). A quercetin- 2HP-β-CD complex has been formerly reported by us. However, once the flavonoid is in its 2HP-β-CD encapsulated state its oxidation potential, its decomplexation mechanism, its potential to protect DNA damage from oxidative stress remained elusive. To unveil this, an array of biophysical techniques was used. Methods: The quercetin-2HP-β-CD complex was evaluated through solubility and dissolution experiments, electrochemical and spectroelectrochemical studies (Cyclic Voltammetry), UV–Vis spectroscopy, HPLC-ESI-MS/MS and HPLC-DAD, fluorescence spectroscopy, NMR Spectroscopy, theoretical calculations (density functional theory (DFT)) and biological evaluation of the protection offered against H2O2-induced DNA damage. Results: Encapsulation of quercetin inside the supramolecule's cavity enhanced its solubility and retained its oxidation profile. Although the protective ability of the quercetin-2HP-β-CD complex against H2O2 was diminished, iron serves as a chemical stimulus to dissociate the complex and release quercetin. Conclusions: We found that in a quercetin-2HP-β-CD inclusion complex quercetin retains its oxidation profile similarly to its native state, while iron can operate as a chemical stimulus to release quercetin from its host cavity. General significance: The oxidation profile of a natural product once it is encapsulated in a supramolecular carrier was unveiled as also it was discovered that decomplexation can be triggered by a chemical stimilus.
- Diamantis, Dimitrios A.,Ramesova, Sarka,Chatzigiannis, Christos M.,Degano, Ilaria,Gerogianni, Paraskevi S.,Karadima, Konstantina E.,Perikleous, Sonia,Rekkas, Dimitrios,Gerothanassis, Ioannis P.,Galaris, Dimitrios,Mavromoustakos, Thomas,Valsami, Georgia,Sokolova, Romana,Tzakos, Andreas G.
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- Elucidation of active site residues of Arabidopsis thaliana flavonol synthase provides a molecular platform for engineering flavonols
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Arabidopsis thaliana flavonol synthase (aFLS) catalyzes the production of quercetin, which is known to possess multiple medicinal properties. aFLS is classified as a 2-oxoglutarate dependent dioxygenase as it requires ferrous iron and 2-oxoglutarate for catalysis. In this study, the putative residues for binding ferrous iron (H221, D223 and H277), 2-oxoglutarate (R287 and S289) and dihydroquercetin (H132, F134, K202, F293 and E295) were identified via computational analyses. To verify the proposed roles of the identified residues, 15 aFLS mutants were constructed and their activities were examined via a spectroscopic assay designed in this study. Mutations at H221, D223, H277 and R287 completely abolished enzymes activities, supporting their importance in binding ferrous iron and 2-oxoglutarate. However, mutations at the proposed substrate binding residues affected the enzyme catalysis differently such that the activities of K202 and F293 mutants drastically decreased to approximately 10% of the wild-type whereas the H132F mutant exhibited approximately 20% higher activity than the wild-type. Kinetic analyses established an improved substrate binding affinity in H132F mutant (Km: 0.027 ± 0.0028 mM) compared to wild-type (Km: 0.059 ± 0.0063 mM). These observations support the notion that aFLS can be selectively mutated to improve the catalytic activity of the enzyme for quercetin production.
- Chua, Chun Song,Biermann, Daniela,Goo, Kian Sim,Sim, Tiow-Suan
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- Structural determination and DPPH radical-scavenging activity of two acylated flavonoid tetraglycosides in oolong tea (Camellia sinensis)
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Two major acylated flavonoid tetraglycosides were isolated from the methanol extract of oolong tea. Their structures were elucidated by spectroscopic methods as quercetin 3-O-[2G-(E)-coumaroyl-3 G-O-β-D-glucosyl-3R-O-β-D-g
- Lee, Viola Szu-Yuan,Chen, Chiy-Rong,Liao, Yun-Wen,Tzen, Jason Tze-Cheng,Chang, Chi-I.
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- Transrutinosylation of tyrosol by flower buds of Sophora japonica
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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
- Karni?ová Potocká, Elena,Mastihuba, Vladimír,Mastihubová, Mária
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- One-pot preparation of quercetin using natural deep eutectic solvents
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In this study, we have established a green and efficient preparation method of quercetin. Rutin was first extracted from Sophora japonica using natural deep eutectic solvents (NADESs), then hydrolyzed into quercetin by rutin degrading enzyme (RDE) obtained from germinated tartary buckwheat in situ. Rutin solubility tests showed that most of the 11 NADESs increased the solubility of rutin by 67-3116 times compared to water. Thus, NADESs could be prior candidate to extract rutin. Extraction efficiency of rutin varied with different NADESs, and a maximum of 291.57 mg g?1 was achieved in NADES ChGly, which was prepared by mixing choline chloride and glycerol at a molar ratio of 1:1. After that hydrolysis was performed directly in extraction system by adding RDE with degradation rate of up to 8.36 mg min-1·L-1. Our findings suggest that preparation of quercetin using NADESs was simple and feasible to operate, environmentally friendly, efficient, and inspired the preparation method of bioactive components from a new perspective.
- Zang, Yuan-Yuan,Yang, Xi,Chen, Zhi-Gang,Wu, Tao
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- Optimization of the biosynthesis of b-ring ortho-hydroxy lated flavonoids using the 4-hydroxyphenylacetate 3-hydroxylase complex (Hpabc) of escherichia coli
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Flavonoids are important plant metabolites that exhibit a wide range of physiological and pharmaceutical functions. Because of their wide biological activities, such as anti-inflammatory, antioxidant, antiaging and anticancer, they have been widely used in foods, nutraceutical and pharmaceuticals industries. Here, the hydroxylase complex HpaBC was selected for the efficient in vivo production of ortho-hydroxylated flavonoids. Several HpaBC expression vectors were constructed, and the corresponding products were successfully detected by feeding naringenin to vector-carrying strains. However, when HpaC was linked with an S-Tag on the C terminus, the enzyme activity was significantly affected. The optimal culture conditions were determined, including a substrate concentration of 80 mg·L?1, an induction temperature of 28?C, an M9 medium, and a substrate delay time of 6 h after IPTG induction. Finally, the efficiency of eriodictyol conversion from P2&3-carrying strains fed naringin was up to 57.67 ± 3.36%. The same strategy was used to produce catechin and caf-feic acid, and the highest conversion efficiencies were 35.2 ± 3.14 and 32.93 ± 2.01%, respectively. In this paper, the catalytic activity of HpaBC on dihydrokaempferol and kaempferol was demonstrated for the first time. This study demonstrates a feasible method for efficiently synthesizing in vivo B-ring dihydroxylated flavonoids, such as catechins, flavanols, dihydroflavonols and flavonols, in a bacterial expression system.
- Chen, Yang,Gao, Liping,Gui, Lin,Guo, Lina,Lei, Ting,Li, Yan,Ma, Xiubing,Ruan, Haixiang,Wang, Longji,Wang, Yunsheng,Xia, Tao
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- Phenolic compounds from Carthamus tinctorius
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The contents of quercetin, luteolin, apigenin, isorhamnetin, umbelliferone, and daphnoretin in common safflower and of acacetin in the flowers were determined based on the physical and chemical properties of the isolated substances.
- Suleimanov
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- Flavonoid glycosides from Astragalus galegiformis leaves
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New flavonoid oligosides, the structures of which were established by chemical transformations and UV, IR, PMR, and 13C NMR spectra, were isolated from Astragalus galegiformis leaves.
- Alaniya,Kavtaradze,Bassarello,Skhirtladze,Pizza,Kutateladze
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- Hydrolysis of scutellarin and related glycosides to scutellarein and the corresponding aglycones
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Scutellarein has been prepared by the hydrolysis of scutellarin with sulfuric acid to provide this biologically important rare flavone in up to > 90% yield and on the 5 g scale in minutes. This protocol has been applied to five other flavonoid glycosides (rutin, hesperidin, naringin, baicalin and diosmin) which are readily hydrolysed to their corresponding aglycones.
- Zhang, Wei,Yi, Dong,Gao, Kai,Liu, Manshuo,Yang, Jian,Liao, Xiali,Yang, Bo
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- Anti-complement activity of constituents from the stem-bark of Juglans mandshurica
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Four known flavonoids and two galloyl glucoses isolated from the stem-bark of Juglans mandshurica (Juglandaceae), namely taxifolin (1), afzelin (2), quercitrin (3), myricitrin (4), 1,2,6-trigalloylglucose (5), and 1,2,3,6-tetragalloylglucose (6), were evaluated for their anti-complement activity against complement system. Afzelin (2) and quercitrin (3) showed inhibitory activity against complement system with 50% inhibitory concentrations (IC50) values of 258 and 440 μM. 1,2,6-Trigalloylglucose (5) and 1,2,3,6-tetragalloylglucose (6) exhibited anti-complement activity with IC 50 values of 136 and 34 μM. In terms of the evaluation of the structure-activity relationship of 3,5,7-trihydroxyflavone, compounds 2, 3, and 4 were hydrolyzed with naringinase to give kaempferol (2a), quercetin (3a), and myricetin (4a) as their aglycones, and these were also tested for their anti-complement activity. Of the three aglycones, kaempferol (2a) exhibited weak anti-complement activity with an IC50 value of 730 μM, while quercetin (3a) and myricetin (4a) were inactive in this assay system. Among the compounds tested, 1,2,3,6-tetragalloylglucose (6) showed the most potent anticomplement activity (IC50, 34 μM).
- Min, Byung-Sun,Lee, Sun-Young,Kim, Jung-Hee,Lee, Joong-Ku,Kim, Tae-Jin,Kim, Dong-Hee,Kim, Young-Ho,Joung, Hyouk,Lee, Hyeong-Kyu,Nakamura, Norio,Miyashiro, Hirotsugu,Hattori, Masao
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- Involvement of rat cytochrome 1A1 in the biotransformation of kaempferol to quercetin: Relevance to the genotoxicity of kaempferol
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Kaempferol is a flavonoid widely distributed in edible plants and has been shown to be genotoxic to V79 cells in the absence of external metabolizing systems. The presence of an external metabolizing system, such as rat liver homogenates (S9 mix), leads to an increase in its genotoxicity, which is attributed to its biotransformation to the more genotoxic flavonoid quercetin, via the cytochrome P450 (CYP) mono-oxygenase system. In the present work we investigated the mechanisms of the genotoxicity of kaempferol further. Special attention has been given to the role of CYP in the genotoxicity of this flavonoid. We studied the induction of mutations in Salmonella typhimurium TA98 in the presence and in the absence of S9 mix and the induction of chromosomal aberrations (CAs) and micronuclei (MN) by kaempferol in V79 cells in the presence and in the absence of S9 mix. To evaluate the role of different CYP in the biotransformation of kaempferol we studied the induction of CAs and MN in V79 cells genetically engineered for the expression of rat CYP 1A1, 1A2 and 2B1. In addition we performed CYP inhibition studies using the above-mentioned indicators and high performance liquid chromatography (HPLC) analysis. The results obtained in this work suggest that rat CYP 1A1 is, among the cytochromes studied, the one that plays the major role in the transformation of kaempferol into quercetin. The relevance of these findings to the human situation is discussed.
- Duarte Silva,Rodrigues,Gaspar,Maia,Laires,Rueff
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- A convenient and safe O-methylation of flavonoids with dimethyl carbonate (DMC)
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Dietary flavonoids exhibit beneficial health effects. Several epidemiological studies have focused on their biological activities, including antioxidant, antibacterial, antiviral, anti-inflammatory and cardiovascular properties. More recently, these compounds have shown to be promising cancer chemopreventive agents in cell culture studies. In particular, O-methylated flavonoids exhibited a superior anticancer activity than the corresponding hydroxylated derivatives being more resistant to the hepatic metabolism and showing a higher intestinal absorption. In this communication we describe a convenient and efficient procedure in order to prepare a large panel of mono- and dimethylated flavonoids by using dimethyl carbonate (DMC), an ecofriendly and non toxic chemical, which plays the role of both solvent and reagent. In order to promote the methylation reaction under mild and practical conditions, 1,8-diazabicyclo[5.4.0]undec-7- ene (DBU) was added in the solution; methylated flavonoids were isolated in high yields and with a high degree of purity. This methylation protocol avoids the use of hazardous and high toxic reagents (diazomethane, dimethyl sulfate, methyl iodide).
- Bernini, Roberta,Crisante, Fernanda,Ginnasi, Maria Cristina
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- Hydrolysis of flavonoid glycosides by propolis β-glycosidase
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Flavonoids generally occur as O-glycosides with sugars bound in nature, while aglycones and their derivatives are the main flavonoids in propolis. The objective of this work was to study the propolis β-glycosidase activities toward flavonoid β-glycosides and their conjugated forms. β-Glycosidase was extracted from propolis, incubated with avonoid glycosides, and analysed for aglycone formation by HPLC. The results demonstrated that glucose conjugates were rapidly hydrolysed, but not conjugates with other sugars, i.e. rutin and naringin. The rate and extent of deglycosylation depends on the structure of the avonoid and the position of the sugar substituitions. Quercetin 3-O-glucoside had the highest percent of hydrolysis, while quercetin 7-O-glucoside was the least hydrolysed. The Km values for hydrolysis of apigenin 7-glucoside and luteolin-7-O-glucoside were 13M and 20M, respectively.
- Zhang, Cui-Ping,Liu, Gang,Hu, Fu-Liang
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- Purification and characterization of a flavonol 3-O-β heterodisaccharidase from the dried herb of Fagopyrum esculentum Moench
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A flavonol-3-O-β-heterodisaccharide glycosidase (FHG I) was isolated from dried aerial tissues of Fagopyrum esculentum Moench (Fagopyri herba). It has a specific enzyme activity of ca. 3.5 nkat mg-1 protein in buffered extracts when rutin (quercetin-3-O-rutinoside) was used as substrate and an optimal enzyme activity was seen at around pH 4.8 and 30 °C. FHG I was purified about 156-fold to apparent homogeneity by hydrophobic interaction, anion exchange and size exclusion chromatographic steps. The apparent molecular mass of FHG I was 74.5 ± 2 kDa as determined by SDS-PAGE and it is a monomeric glycoprotein with a carbohydrate content of 23%. The isoelectric point as determined by isoelectric focusing was 5.7 and the energy of activation was 32 kJ mol-1. FHG I exhibits a high substrate specificity, preferring flavonol 3-O-glycosides comprising the disaccharide rutinose. The Km and Vmax values for the natural substrate rutin were calculated to be 0.561 μM and 745 nkat mg -1 protein, respectively. Two oligopeptide fragments obtained after enzymatic digestion of FHG I were sequenced and showed similarities to sequences of β-glucohydrolases from other plant species. Polyclonal antibodies were raised and their specificities determined. Another flavonol 3-O-β -heterodisaccharide glycosidase (FHG II) could also be detected in buckwheat herb, having a molecular mass of 85.3 ± 2 kDa and an isoelectric point between pH 6.0 and 6.5.
- Baumgertel, Andreas,Grimm, Rudi,Eisenbeiss, Wilhelm,Kreis, Wolfgang
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- Transformation of rutin to antiproliferative quercetin-3-glucoside by aspergillus niger
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The flavonol quercetin in plants and foods occurs predominantly in the form of glycoside whose sugar moiety affects the bioavailability and the mechanism of its biological activities. The antiproliferative activities of quercetin derivatives such as quercetin aglycone, quercetin-3-ss-D-glucoside (Q3G), and rutin were compared using six different cancer cell lines including colon, breast, hepatocellular, and lung cancer. The IC50 value of Q3G ranged between 15 and 25 μM in HT-29, HCT 116, MCF-7, HepG2, and A549 cells. In these five cell lines, Q3G showed the most potent growth inhibition, whereas rutin showed the least potency. Transformation of rutin to Q3G was conducted by controlling R-L-rhamnosidase and ss-D-glucosidase activities from crude enzyme extract of Aspergillus niger. Carbon sources during culture and transformation conditions such as pH, temperature, and heatstability were optimized. After 4 h biotransformation, 99% of rutin was transformed to Q3G and no quercetin was detected. This study presented an efficient biotransformation for the conversion of rutin to Q3G which was newly shown to have more potent antiproliferative effect than quercetin and rutin. 2010 American Chemical Society.
- Ju You, Hyun,Jin Ahn, Hyung,Ji, Geun Eog
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- Isolation and characterization of a new allelochemical from seeds of Adenanthera pavonina linn
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A new allelochemical (1), m.p. 282-284 °C, m.f. C31H 36O19, [M]+ 712 (FABMS), has been isolated from methanolic extract of the seeds of Adenanthera pavonina Linn. alongwith two known compounds 2',4',7-trihydroxy isoflavone and isovitexin. The structure of a new compound was characterized as 3,5,7,3',4'-pentahydroxy flavone-3'-O-α-L- rhamnopyranosyl-(1→4)-O-α-L-arabinopyranosyl-(1→3)- O-b-D- xylopyranoside, by various colour reactions, spectral analysis and chemical degradations.
- Yadava,Vishwakarma, Umesh Kumar
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- The thermal and enzymatic taxifolin-alphitonin rearrangement
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This report describes a detailed investigation of the thermal and enzymatic conversion of taxifolin to alphitonin. Chromatographic separation of the four dihydroquercetin stereoisomers 1-4 in combination with circular dichroism spectroscopy permitted elucidation of the kinetics of this rearrangement and characterization of the different reaction pathways involved. Our findings are corroborated by quantum chemistry calculations that reveal a unique cascade of tautomerization processes leading from taxifolin to alphitonin and also explain the racemization of alphitonin at room temperature. Furthermore, the substrate specificity toward (+)-taxifolin of an enzyme from Eubacterium ramulus catalyzing this intriguing rearrangement is demonstrated.
- Elsinghorst, Paul W.,Cavlar, Taner,Mueller, Anna,Braune, Annett,Blaut, Michael,Guetschow, Michael
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- Isolation, characterization, complete structural assignment, and anticancer activities of the methoxylated flavonoids from rhamnus disperma roots
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Different chromatographic methods including reversed-phase HPLC led to the isolation and purification of three O-methylated flavonoids; 5,4’-dihydroxy-3,6,7-tri-O-methyl flavone (penduletin) (1), 5,3’-dihydroxy-3,6,7,4’,5’-penta-O-methyl flavone (2), and 5-hydroxy-3,6,7,3’,4’,5’-hexa-O-methyl flavone (3) from Rhamnus disperma roots. Additionlly, four flavonoid glycosides; kampferol 7-O-α-L-rhamnopyranoside (4), isorhamnetin-3-O-β-D-glucopyranoside (5), quercetin 7-O-α-L-rhamnopyranoside (6), and kampferol 3, 7-di-O-α-L-rhamnopyranoside (7) along with benzyl-O-β-D-glucopyranoside (8) were successfully isolated. Complete structure characterization of these compounds was assigned based on NMR spectroscopic data, MS analyses, and comparison with the literature. The O-methyl protons and carbons of the three O-methylated flavonoids (1–3) were unambiguously assigned based on 2D NMR data. The occurrence of compounds 1, 4, 5, and 8 in Rhamnus disperma is was reported here for the first time. Compound 3 was acetylated at 5-OH position to give 5-O-acetyl-3,6,7,3’,4’,5’-hexa-O-methyl flavone (9). Compound 1 exhibited the highest cytotoxic activity against MCF 7, A2780, and HT29 cancer cell lines with IC50 values at 2.17 μM, 0.53 μM, and 2.16 μM, respectively, and was 2–9 folds more selective against tested cancer cell lines compared to the normal human fetal lung fibroblasts (MRC5). It also doubled MCF 7 apoptotic populations and caused G1 cell cycle arrest. The acetylated compound 9 exhibited cytotoxic activity against MCF 7 and HT29 cancer cell lines with IC50 values at 2.19 μM and 3.18 μM, respectively, and was 6–8 folds more cytotoxic to tested cancer cell lines compared to the MRC5 cells.
- Abd El-Wahab, Mohammed F.,Abdalla, Ashraf N.,Mohammed, Abd El-Salam I.,Mohammed, Hamdoon A.,Ragab, Ehab A.,Shaheen, Usama
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- Rutinosidase from Aspergillus niger: crystal structure and insight into the enzymatic activity
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Rutinosidases (α-l-rhamnosyl-β-d-glucosidases) catalyze the cleavage of the glycosidic bond between the aglycone and the disaccharide rutinose (α-l-rhamnopyranosyl-(1→6)-β-d-glucopyranose) of specific flavonoid glycosides such as rutin (quercetin 3-O-rutinoside). Microbial rutinosidases are part of the rutin catabolic pathway, enabling the microorganism to utilize rutin and related plant phenolic glycosides. Here, we report the first three-dimensional structure of a rutinosidase determined at 1.27-? resolution. The rutinosidase from Aspergillus?niger K2 (AnRut), a member of glycoside hydrolase family GH-5, subfamily 23, was heterologously produced in Pichia?pastoris. The X-ray structure of AnRut is represented by a distorted (β/α)8 barrel fold with its closest structural homologue being an exo-β-(1,3)-glucanase from Candida?albicans (CaExg). The catalytic site is located in a deep pocket with a striking structural similarity to CaExg. However, the entrance to the active site of AnRut has been found to be different from that of CaExg – a mostly unstructured section of ~?40 residues present in CaExg is missing in AnRut, whereas an additional loop of 13 amino acids partially covers the active site of AnRut. NMR analysis of reaction products provided clear evidence for a retaining reaction mechanism of AnRut. Unexpectedly, quercetin 3-O-glucoside was found to be a better substrate than rutin, and thus, AnRut cannot be considered a typical diglycosidase. Mutational analysis of conserved active site residues in combination with in?silico modeling allowed identification of essential interactions for enzyme activity and helped to reveal further details of substrate binding. The protein sequence of AnRut has been revised. Databases: The nucleotide sequence of the rutinosidase-encoding gene is available in the GenBank database under the accession number MN393234. Structural data are available in the PDB database under the accession number 6I1A. Enzyme: α-l-Rhamnosyl-β-d-glucosidase (EC?3.2.1.168).
- Pachl, Petr,Kape?ová, Jana,Brynda, Ji?í,Biedermannová, Lada,Pelantová, Helena,Bojarová, Pavla,K?en, Vladimír,?ezá?ová, Pavlína,Kotik, Michael
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p. 3315 - 3327
(2020/02/04)
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- Flexibility modulates the catalytic activity of a thermostable enzyme: Key information from optical spectroscopy and molecular dynamics simulation
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Enzymes are dynamical macromolecules and their conformation can be altered via local fluctuations of side chains, large scale loop and even domain motions which are intimately linked to their function. Herein, we have addressed the role of dynamic flexibility in the catalytic activity of a thermostable enzyme almond beta-glucosidase (BGL). Optical spectroscopy and classical molecular dynamics (MD) simulation were employed to study the thermal stability, catalytic activity and dynamical flexibility of the enzyme. An enzyme assay reveals high thermal stability and optimum catalytic activity at 333 K. Polarization-gated fluorescence anisotropy measurements employing 8-anilino-1-napthelenesulfonic acid (ANS) have indicated increasing flexibility of the enzyme with an increase in temperature. A study of the atomic 3D structure of the enzyme shows the presence of four loop regions (LRs) strategically placed over the catalytic barrel as a lid. MD simulations have indicated that the flexibility of BGL increases concurrently with temperature through different fluctuating characteristics of the enzyme's LRs. Principal Component Analysis (PCA) and the Steered Molecular Dynamics (SMD) simulation manifest the gatekeeper role of the four LRs through their dynamic fluctuations surrounding the active site which controls the catalytic activity of BGL.
- Adhikari, Aniruddha,Biswas, Pritam,Choudhury, Sudeshna Shyam,Das, Monojit,Das, Ranjan,Pal, Samir Kumar,Pal, Uttam,Saha-Dasgupta, Tanusri,Singh, Priya
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p. 3050 - 3062
(2020/04/08)
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- A natural hyperoside based novel light-up fluorescent probe with AIE and ESIPT characteristics for on-site and long-term imaging of β-galactosidase in living cells
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Fluorescence-based on-site and long-term sensing and bioimaging of biomarkers are highly desired for effective diagnosis. Aggregation-induced emission luminogens (AIEgens) with excited-state intramolecular proton transfer (ESIPT) characteristics have outstanding advantages in biological applications due to their large Stokes shift and low background signal in the aggregate state. However, most of the reported AIEgens are fabricated through rational design and complex synthesis procedures. Importantly, with rich structural skeletons and ease of access, natural products have superiority in developing promising AIEgens with ESIPT. Here, hyperoside(quercetin-3-O-β-galactoside) has been easily obtained fromHedyotis diffusa. After the incubation of hyperoside with β-galactosidase (β-Gal), the hydrolysis product, hydrophobic quercetin, is aggregatedin situ, which presents AIE and ESIPT characteristics with a large Stokes shift (170 nm). Then, a novel light-up fluorescent probe has been fabricated for the detection of β-Gal with a good linear relationship (0.03-12 U mL?1), high sensitivity (a detection limit of 0.013 U mL?1) and superior selectivity. Meanwhile, excellent biocompatibility, low cytotoxicity, outstanding photostability, and good intracellular retention demonstrate its superiority for on-site and long-term (about 8 h) imaging of β-Gal in SKOV-3 cells. The results demonstrate the application of hyperoside in the sensing and imaging of β-Gal in biological samples, and propose the great possibility of natural products for developing novel AIE-based fluorescence probes.
- Fu, Qiachi,Guo, Ying,Long, Ruiqing,Shi, Shuyun,Tang, Cui,Tong, Chaoying,Wang, Daijie,Xu, Jinju,Yang, Zan
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supporting information
p. 11860 - 11865
(2020/09/16)
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- Flavonol Glycosides from Leaves of Allium microdictyon
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The composition of flavonoids from leaves of Allium microdictyon Prokh. (Amaryllidaceae) was studied for the first time and included 14 compounds including two new flavonol glycosides 1 and 2. UV, IR, and NMR spectroscopic and mass spectrometric data dete
- Olennikov
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p. 1035 - 1039
(2020/11/03)
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- Reductive dehalogenation and dehalogenative sulfonation of phenols and heteroaromatics with sodium sulfite in an aqueous medium
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Prototropic tautomerism was used as a tool for the reductive dehalogenation of (hetero)aryl bromides and iodides, or dehalogenative sulfonation of (hetero)aryl chlorides and fluorides, using sodium sulfite as the sole reagent in an aqueous medium. This protocol does not require a metal or phase transfer catalyst and avoids using organic solvent as the reaction medium. This method is especially suitable for substrates that readily tautomerize (such as 2-or 4-halogenated aminophenols and 4-halogenated resorcinols), for which dehalogenation or sulfonation proceeds under mild reaction conditions (≤60 °C). As sodium sulfite is an inexpensive, safe, and environmentally less hazardous reagent, this method has at least three potential applications: (i) in the deprotection of halogens as protecting groups, using sodium sulfite as a reducing agent; (ii) in the sulfonation of aromatic halides under mild reaction conditions avoiding hazardous and corrosive reagents/solvents; and (iii) in the transformation of toxic halogenated aromatics into less harmful compounds.
- Tomanová, Monika,Jedinák, Luká?,Canka?, Petr
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supporting information
p. 2621 - 2628
(2019/06/03)
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- Isoquercetin and derivative and application and preparation methods thereof
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The invention provides an isoquercetin and derivative. The structural formula of the isoquercetin and derivative is shown as the formula I, wherein n=1-9, and R is selected from Glu, Rha, Gal, Xyl orAll. The isoquercetin and derivative solves the problem of poor solubility of rutin and quercetin as well as in vivo digestion and absorption of rutin, improves the bioavailability of isoquercetin andpolysaccharide isoquercetin and achieves significant therapeutic effects on prevention and treatment of osteoporosis and hyperlipidemia.
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-
Paragraph 0021; 0022
(2019/04/09)
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- Oxidative Transformation of Leucocyanidin by Anthocyanidin Synthase from Vitis vinifera Leads only to Quercetin
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Anthocyanidin synthase from Vitis vinifera (VvANS) catalyzes the in vitro transformation of the natural isomer of leucocyanidin, 2R,3S,4S-cis-leucocyanidin, into 2R,4S-flavan-3,3,4-triol ([M + H]+, m/z 323) and quercetin. The C3-hydroxylation product 2R,4S-flavan-3,3,4-triol is first produced and its C3,C4-dehydration product is in tautomeric equilibrium with (+)-dihydroquercetin. The latter undergoes a second VvANS-catalyzed C3-hydroxylation leading to a 4-keto-2R-flavan-3,3-gem-diol which upon dehydration gives quercetin. The unnatural isomer of leucocyanidin, 2R,3S,4R-trans-leucocyanidin, is similarly transformed into quercetin upon C3,C4-dehydration, but unlike 3,4-cis-leucocyanidin, it also undergoes some C2,C3-dehydration followed by an acid-catalyzed hydroxyl group extrusion at C4 to give traces of cyanidin. Overall, the C3,C4-trans isomer of leucocyanidin is transformed into 2R,4R-flavan-3,3,4-triol (M + 1, m/z 323), (+)-DHQ, (-)-epiDHQ, quercetin, and traces of cyanidin. Our data bring the first direct observation of 3,4-cis-leucocyanidin- and 3,4-trans-leucocyanidin-derived 3,3-gem-diols, supporting the idea that the generic function of ANS is to catalyze the C3-hydroxylation of its substrates. No cyanidin is produced with the natural cis isomer of leucocyanidin, and only traces with the unnatural trans isomer, which suggests that anthocyanidin synthase requires other substrate(s) for the in vivo formation of anthocyanidins.
- Zhang, Jia-Rong,Trossat-Magnin, Claudine,Bathany, Katell,Delrot, Serge,Chaudière, Jean
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p. 3595 - 3604
(2019/03/29)
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- Flavonoid aromatizing enzyme inhibitor as well as preparation method and application thereof
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The invention relates to a flavonoid aromatizing enzyme inhibitor. Through cyanomethylation reaction and alkylation reaction, some substituted groups on the mother ring of a flavonoid compound are changed and a series of flavonoid compounds and derivatives thereof are synthesized. The structural general formula can be shown in the general formula in claims. In the structural general formula, R1 isselected from any one of -OH or -H, R2 is selected from any one of -H, -OCH3 or -OH, R3 is selected from any one of -H, -OH, -OCH2CN or -OCH3, R4 is selected from any one of -H, -OH, -CH2Ph or -2-(2-methoxy-2-oxo ethyl)benzyloxy, R5 is selected from any one of -H, -OCH2Ph or -OCH3, and R6 is selected from any one of -H, -OH or -OCH3. The flavonoid compounds have good inhibition effect on aromatizing enzyme; through activity test, the maximal value IC50 of inhibiting the activity of the aromatizing enzyme by the inhibitor is equal to 0.251 [mu]mol/L.
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Paragraph 0040
(2018/07/30)
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- New assay of α-l-rhamnosidase
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Abstract: Free rutinose was prepared by enzymatic hydrolysis of rutin using defatted seed meal from tartary buckwheat. This disaccharide was used as substrate in spectrophotometric assay of α-l-rhamnosidase. The assay is based on hydrolysis of rutinose and subsequent determination of released glucose by a standard glucose oxidase assay kit. The method is easy to perform and requires no expensive equipment. The assay was applied in α-l-rhamnosidase estimation in ten commercial enzyme preparations and compared with standard assay on chromogenic substrate.
- Karni?ová Potocká, Elena,Mastihubová, Mária,?i?ová, Iveta,Mastihuba, Vladimír
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p. 167 - 174
(2017/12/06)
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- Effects of Zanthoxylum piperitum ethanol extract on osteoarthritis inflammation and pain
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Degenerative arthritis, also known as osteoarthritis (OA), is the most common type of arthritis, which is caused by degenerative damage of the cartilage, which primarily protects the joints, leading to inflammation and pain. The objective of this study was to investigate the in vivo and in vitro effects of treatment with ZPE-LR (90% EtOH extract of Zanthoxylum piperitum) on pain severity and inflammation. When using an in vivo OA model MIA (monosodiumidoacetate-induced arthritis) rats, ZPE-LR (100 mg/kg) oral-administratio significantly inhibited MIA-induced change in loaded weight ratio on the left foot, and articular cartilage thickness. To confirm the positive effects on pain relief, acetic acid, heat and formalin-induced pain were remarkably decreased by 50 and 100 mg/kg ZPE-LR oral-administration. Pain related KCNJ6 mRNA expression as well as K + current was increased after ZPE-LR treatment in BV-2 cells. To confirm the positive effects on inflammation, TPA (12-O-tetradecanoylphorbol-13-acetate) induced inflammation measured by mouse ear thickness and biopsy punch weight and TPA-induced iNOS, COX-2 mRNA and protein expression were remarkably suppressed by 50 and 100 mg/kg ZPE-LR oral-administration. In addition, TPA-induced iNOS, COX-2 mRNA level and protein expression were reduced. Acetic acid, heat and formalin-induced pain were remarkably decreased by 50 and 100 mg/kg ZPE-LR oral-administration. We examined in vitro ZPE-LR effects in LPS-induced RAW 264.7 cells. LPS-induced p65 translocation to the nucleus was prohibited by ZPE-LR 100 μg/ml oral administration. Moreover, ROS generation by LPS was significantly inhibited by ZPE-LR 50 and 100 μg/ml treatment. To investigate new ZPE-LR activating mechanisms, the gene fishing method (not a typical term, should probably use PCR based genetic screening) was used. LPS-induced HPRT1 (hypoxanthine phosphoribosyltransferase 1) was decreased by ZPE-LR. However, RPL8 (Ribosomal protein L8) which showed no change in mRNA expression due to LPS, did show increased mRNA levels after ZPE-LR treatment. Our data elucidate mechanisms underlying ZPE-LR and suggest ZPE-LR may be a potential therapeutic agent to modulate osteoarthritis inflammation and pain.
- Hwang, Kyung-A,Kwon, Jeong Eun,Noh, YooHun,Park, BongKyun,Jeong, Yong Joon,Lee, Sun-Mee,Kim, Se-Young,Kim, InHye,Kang, Se Chan
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p. 481 - 490
(2018/06/07)
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- Exploratory Studies on the in Vitro Anti-inflammatory Potential of Two Herbal Teas (Annona muricata L. and Jasminum grandiflorum L.), and Relation with Their Phenolic Composition
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The need of new anti-inflammatory drugs has led to the search for safer and more potent molecules in distinct sources, such as natural products. This work aimed to explore the anti-inflammatory potential of aqueous extracts from two herbal teas (Annona muricata L. and Jasminum grandiflorum L.) in RAW 264.7 macrophages cells and in cell-free assays. Furthermore, the phenolic composition of both extracts and of their hydrolysates was characterized by HPLC-DAD, in order to establish possible relationships with the biological activity. In a general way, A.?muricata displayed a stronger capacity to inhibit nitric oxide (NO) production and the activity of phospholipase A2 (PLA2), displaying an IC50 value of 142?μg/ml against this enzyme. A deeper look at phenolic compounds revealed that aglycones had more capacity to inhibit NO and PLA2 than their corresponding glycosides, quercetin being clearly the most potent one (IC50?=?7.47 and 1.36?μm, respectively). In addition, 5-O-caffeoylquinic acid, at 1.56?μm, could also inhibit PLA2 (ca. 35%). Our findings suggest that the consumption of both herbal teas may be a preventive approach to inflammatory disorders.
- Oliveira, Andreia P.,Sá, Ivone,Pereira, David M.,Gon?alves, Rui F.,Andrade, Paula B.,Valent?o, Patrícia
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- Spireasalicin, a New Acylated Quercetin Glycoside from Spiraea salicifolia
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A new acylated quercetin glycoside and 36 known compounds were isolated from flowering runners of Spiraea salicifolia L. (Rosaceae). The structures of the new glycoside quercetin-3-O-[6″-(4?-hydroxy-2?-methylenebutyroyl)]-β-D-glucopyranoside (spireasalicin, 1) and the 36 known compounds were elucidated using UV, IR, and NMR spectroscopy and mass spectrometry. The biological screening of the isolated compounds showed that 1 inhibited α-glucosidase. The contents of several phenolic compounds in S. salicifolia organs were studied and found to be unevenly distributed in the separate plant parts.
- Olennikov,Kashchenko
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p. 1038 - 1044
(2017/12/04)
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- Flavonoid glycosides from Sedum bulbiferum
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The MeOH extract from dried whole Sedum bulbiferum MAKINO (Crassulaceae) plants yielded 34 compounds, including six new flavonoid glycosides and 28 known compounds. The structures of new compounds were established using NMR, Mass spectroscopic analysis an
- Warashina, Tsutomu,Miyase, Toshio
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p. 1199 - 1204
(2017/12/26)
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- Anti-inflammatory and Antiosteoporosis Flavonoids from the Rhizomes of Helminthostachys zeylanica
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Chemical investigation of the rhizomes of Helminthostachys zeylanica led to the isolation of eight new flavonoids including six cyclized geranylflavonoids, ugonins V-X (1-3), (10R,11S)-ugonin N (4), (10R,11S)-ugonin S (5), and ugonin Y (6), as well as two quercetin glucosides, quercetin-4′-O-β-d-glucopyranosyl-(1→2)-β-d-glucopyranoside (7) and quercetin-3-O-β-d-glucopyranosyl-4′-O-β-d-glucopyranosyl-(1→2)-β-d-glucopyranoside (8). The structures of these compounds were established by spectroscopic analyses and acid hydrolysis of the sugar moiety. Among the isolated compounds, 1, 2, 5, 6, ugonins J-S (9-13), ugonstilbene A (14), and ugonin L (23) were evaluated for their anti-inflammatory activity on lipopolysaccharide-induced nitric oxide (NO) production in microglial cells. Except for 1, 5, and 13, all other compounds inhibited NO production with IC50 values of 6.2-10.1 μM and were more potent than the positive control, pyrrolidine dithiocarbamate. Compounds 1, 2, 5, 6, and 10-13 were tested for antiosteoporotic activities, and ugonin K (10) exhibited the highest inhibitory activity against RANKL-induced osteoclast differentiation in RAW264.7 cells with an IC50 value of 1.8 ± 0.2 μM.
- Huang, Yu-Ling,Shen, Chien-Chang,Shen, Yuh-Chiang,Chiou, Wen-Fei,Chen, Chien-Chih
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p. 246 - 253
(2017/03/09)
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- Method for extracting rutin from Japanese pagodatree flower buds and preparing quercetin
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The invention belongs to the technical field of traditional Chinese medicine and particularly relates to a method for extracting rutin from Japanese pagodatree flower buds and preparing quercetin. The quercetin as an effective component in the Japanese pagodatree flower buds belongs to flavonoid compounds, rutin is rutinoside of the quercetin, and the rutin and the quercetin belong to different substances and have different pharmacological characteristics. By the aid of the property that the rutin has different solubility in cold water and hot water, the rutin is separated and extracted from the Japanese pagodatree flower buds and subjected to ethyl alcohol reflux refining, refined rutin with higher purity can be obtained, then the rutin is hydrolyzed in an acidic condition, the quercetin can be obtained and subjected to recrystallization with ethyl alcohol, and yellow acicular crystals can be obtained and are refined quercetin products.
- -
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Paragraph 0016; 0021; 0022; 0023; 0024; 0025-0041
(2016/11/24)
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- Reactions of flavonoids with o-quinones interfere with the spectrophotometric assay of tyrosinase activity
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Flavonoids are important food components with antioxidant properties and many of them have been described as tyrosinase inhibitors. Oxidation of quercetin, kaempferol, morin, catechin, and naringenin by mushroom tyrosinase and their influence on the oxidation of l-dopa and l-tyrosine was studied. Reaction rates measured spectrophotometrically and by oxygen consumption differed substantially. All tested flavonoids reacted with 4-tert-butyl-o-benzoquinone and/or 4-methyl-o-benzoquinone, although at different rates. These reactions generated products whose UV-vis spectra either overlapped or did not overlap with the spectrum of dopachrome. They therefore strongly influence the kinetic analysis performed by measuring the absorbance at 475 nm during oxidation of l-dopa or l-tyrosine generating false inhibition or activation effects. This method is therefore inappropriate for monitoring the activity of this enzyme in the presence of flavonoids and other compounds possessing strong nucleophilic or reducing groups.
- Gasowska-Bajger, Beata,Wojtasek, Hubert
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p. 5417 - 5427
(2016/07/19)
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- Expanded investigations of the aglycon promiscuity and catalysis characteristic of flavonol 3-: O -rhamnosyltransferase AtUGT78D1 from Arabidopsis thaliana
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Rhamnosides usually possess better bioavailabilities and improved solubilities compared with their aglycons and are a major source of bioactive natural products. However, biosynthesis of rhamnosides is hindered by the commercially expensive UDP-rhamnose (UDP-Rha) donor and a lack of universal rhamnosyltransferases. In the present study, an efficient UDP-Rha production system via a two-step enzymatic reactions using UDP-glucose (UDP-Glc) as a substrate was constructed. Extensive in vitro enzymatic assays and preparative reactions using the obtained UDP-Rha/UDP-Glc highlighted the robust glycosylation promiscuity of the reported rhamnosyltransferase AtUGT78D1. Based on HPLC-UV and HR-MS analyses, 30 of the tested aromatic compounds belonging to 7 structural types, including flavonoids, flavonoid glycosides, phenylethyl chromones, benzophenones, coumarins, lignanoids, and anthraquinones, were accepted by AtUGT78D1 to conduct the corresponding rhamnosylation and/or glucosylation with one or more glycosyl substitutions at different positions. Further preparative reactions expanded the catalytic characteristic of AtUGT78D1 since it can catalyse the rhamnosylation at the 3-OH position of the flavonols, glucosylation at the 7-OH position of the flavone baicalein, and multiple hydroxyl substitutions for diverse types of aromatics. Interestingly, a unique reversible catalysis activity of AtUGT78D1 was observed, and it has been effectively used in one-pot rhamnosylation of the desired rhamnoside. The enzymatic rhamnosylations of diverse "drug-like" scaffolds as well as bidirectional catalysis for one-pot rhamnosylations by plant rhamnosyltransferase were rarely reported before, which indicated that AtUGT78D1 was expected to be a universal and effective tool for chemo-enzymatic synthesis of diverse bioactive rhamnosylated derivatives for drug discovery.
- Mo, Ting,Liu, Xiao,Liu, Yuyu,Wang, Xiaohui,Zhang, Le,Wang, Juan,Zhang, Zhongxiu,Shi, Shepo,Tu, Pengfei
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p. 84616 - 84626
(2016/11/02)
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- Two new P-coumaroyl flavonoid glycosides having Cytokine increasing activity from Centaurium spicatum L
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Two new P-coumaroyl flavonol glycosides, Kaempferol 3-O-[β-D-glucopyranosyl- (1?→?4)-α-L-rhamnopyranosyl-(1?→?4)-α-L-rhamnopyranosyl-(1?→?6)-(4 trans- P-coumaroyl)]-β-D- galactopyranoside (1) and Quercetin 3-O-[β-D-glucopyranosyl-(1?→?4)-α-L-rhamnopyranos
- Allam, Ahmed E.,Nafady, Alaa M.,Hassanein, Ahmed M.M.,Mostafa, Mahmoud A.H.,El-Shanawany, Mohamed A.,Takano, Fumide,Ohta, Tomihisa
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p. 144 - 151
(2016/07/20)
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- Laccase-catalyzed dimerization of glycosylated lignols
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Phenylpropanoid glucosides (PPGs) are naturally occurring and bioactive phenolic derivatives, largely distributed in plants. In this work different PPGs have been chemically or enzymatically synthesized from the lignols coniferyl and p-coumaryl alcohols as substrates for a laccase-catalyzed oxidative coupling. The biooxidation of these PPGs has been investigated here and novel dihydrobenzofuran-based structurally modified analogues have been isolated and characterized. Specifically, the presence of a carbohydrate moiety increased the water solubility of these compounds and reduced the number of dimeric products, as pinoresinol-like structures could not be formed. Looking for a possible sugar-promoted stereochemical enrichment of the obtained diastereomeric mixtures of dimers, different carbohydrate moieties (D-glucose, L-glucose and the disaccharide rutinose) were considered and the respective d.e. values of the dimeric products were measured by 1H NMR and HPLC. However, it was found that the sugar substituent had a minor effect on the stereochemical outcome of the radical coupling reactions, the best measured result being a d.e. value of 21%.
- Bassanini, Ivan,Gavezzotti, Paolo,Monti, Daniela,Krejzová, Jana,K?en, Vladimír,Riva, Sergio
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p. 295 - 301
(2016/12/16)
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- α-L-Rhamnosyl-β-D-glucosidase (rutinosidase) from Aspergillus niger: Characterization and synthetic potential of a novel diglycosidase
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We report the first heterologous production of a fungal rutinosidase (6-O-α-L-rhamnopyranosyl-β-D-glucopyranosidase) in Pichia pastoris. The recombinant rutinosidase was purified from the culture medium to apparent homogeneity and biochemically characterized. The enzyme reacts with rutin and cleaves the glycosidic linkage between the disaccharide rutinose and the aglycone. Furthermore, it exhibits high transglycosylation activity, transferring rutinose from rutin as a glycosyl donor onto various alcohols and phenols. The utility of the recombinant rutinosidase was demonstrated by its use for the synthesis of a broad spectrum of rutinosides of primary (saturated and unsaturated), secondary, acyclic and phenolic alcohols as well as for the preparation of free rutinose. Moreover, the α-L-rhamnosidase-catalyzed synthesis of a chromogenic substrate for a rutinosidase assay - para-nitrophenyl β-rutinoside - is described.
- imkov, Daniela,Kotik, Michael,Weignerov, Lenka,Halada, Petr,Pelantov, Helena,Adamcov, Kateina,Ken, Vladimr
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supporting information
p. 107 - 117
(2015/01/30)
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- Application of spectroscopic methods for identification (FT-IR, Raman spectroscopy) and determination (UV, EPR) of quercetin-3-O-rutinoside. Experimental and DFT based approach
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Vibrational (FT-IR, Raman) and electronic (UV, EPR) spectral measurements were performed for an analysis of rutin (quercetin-3-O-rutinoside) obtained from Rutaofficinalis. The identification of rutin was done with the use of FT-IR and Raman spectra. Those experimental spectra were determined with the support of theoretical calculations based on a DFT method with the B3LYP hybrid functional and 6-31G(d,p) basis set. The application of UV and EPR spectra was found to be a suitable analytical approach to the evaluation of changes in rutin exposed to certain physicochemical factors. Differences in absorbance observed in direct UV spectra were used to monitor changes in the concentration of rutin in degraded samples. Spectra of electron paramagnetic resonance allowed studying the process of free-radical quenching in rutin following its exposure to light. The molecular electrostatic potential (MEP) and frontier molecular orbitals (LUMO-HOMO) were also determined in order to predict structural changes and reactive sites in rutin.
- Paczkowska, Magdalena,Lewandowska, Kornelia,Bednarski, Waldemar,Mizera, Miko?aj,Podborska, Agnieszka,Krause, Anna,Cielecka-Piontek, Judyta
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p. 132 - 139
(2015/07/27)
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- Dhasingreoside: New flavonoid from the stems and leaves of Gaultheria fragrantissima
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A new flavonoid, dhasingreoside (1) and seven known compounds, quercetin 3-O-β-d-galacturonopyranoside (2), quercetin 3-O-β-d-galactopyranoside (3), quercetin 3-O-β-d-glucuronopyranoside (4), quercetin 3-O-α-l-rhamnopyranoside (5), (-)-epicatechin (6), salicylic acid (7) and gaultherin (8), have been isolated from the shade-dried stems and leaves of Gaultheria fragrantissima, commonly known as Dhasingre in Nepal. The structures were elucidated on the basis of physical, chemical and spectroscopic methods. Among known compounds, five compounds (3-6 and 8) were isolated for the first time from G. fragrantissima. In vitro antioxidant activity of all the isolated compounds was evaluated by 1,1-diphenyl-2-picrylhydrazyl free radical-scavenging assay. Dhasingreoside (1) and other compounds (2-6) showed significant free radical-scavenging activity.
- Cong, Fei,Joshi, Khem Raj,Devkota, Hari Prasad,Watanabe, Takashi,Yahara, Shoji
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p. 1442 - 1448
(2015/03/05)
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- Novel flavonol glycosides from the aerial parts of lentil (Lens culinaris)
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While the phytochemical composition of lentil (Lens culinaris) seeds is well described in scientific literature, there is very little available data about secondary metabolites from lentil leaves and stems. Our research reveals that the aerial parts of lentil are a rich source of flavonoids. Six kaempferol and twelve quercetin glycosides were isolated, their structures were elucidated using NMR spectroscopy and chemical methods. This group includes 16 compounds which have not been previously described in the scientific literature: quercetin 3-O-P-D-glucopyranosyl(1→2)-β-D-galactopyranoside-7-O-β-D-glucuropyranoside (1), kaempferol 3-O-β-D-glucopyranosyl(1→2)-β-D-galactopyranoside-7-O-β-D-glucuropyranoside (3), their derivatives 4-10,12-15,17,18 acylated with caffeic, p-coumaric, ferulic, or 3,4,5-trihydroxycinnamic acid and kaempferol 3-O-{[(6-O-E - p-coumaroyl)-β-D-glucopyranosyl(1→2)]-α-L-rhamnopyranosyl(1-6)}-β-D-galactopyranoside-7-O-α-L-rhamnopyranoside (11). Their DPPH scavenging activity was also evaluated. This is probably the first detailed description of flavonoids from the aerial parts of lentil.
- Zuchowski, Jerzy,Pecio, Lukasz,Stochmal, Anna
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p. 18152 - 18178
(2015/02/19)
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- Urgineaglyceride A: A new monoacylglycerol from the Egyptian Drimia maritima bulbs
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One new compound, (2S)-1-O-(Z)-tetracos-6-enoate glycerol (1) named urgineaglyceride A, along with six known compounds, 3,5,7,3′,5′-pentahydroxydihydroflavonol (2), stigmasterol (3), (25S)-5β-furostane-3β-22α-26-triol (4), scillaridin A (5), (2S)-(+)-2-hydroxynaringenin-4′-O-β-d-glucopyranoside (6) and quercetin-3′-O-β-d-glucopyranoside (7), were isolated from the EtOAc fraction of Drimia maritima (L.) Stearn bulbs. Their structures were secured based on their IR, UV, 1D and 2D NMR data, in addition to HR-MS data and comparison with the literature data. The isolated compounds were evaluated for their in vitro growth inhibitory activity against A549 non-small cell lung cancer (NSCLC), U373 glioblastoma (GBM) and PC-3 prostate cancer cell lines. Compounds 2 and 3 displayed variable activities against the tested cancer cell lines. Compound 2 was a selective inhibitor of the NSCLC cell line with an IC50 of 2.3 μM, whereas 3 was selective against GBM with IC50 of 0.5 μM and against PC-3 with 2.0 M.
- Mohamed, Gamal A.,Ibrahim, Sabrin R. M.,Shaala, Lamiaa A.,Alshali, Khalid Z.,Youssef, Diaa T. A.
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p. 1583 - 1590
(2015/11/04)
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- Flavonol glycosides with α-Glucosidase inhibitory activities and new flavone C-diosides from the leaves of machilus konishii
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Seventeen flavonoids, five of which are flavone C-diosides, 1 - 5, were isolated from the BuOH- And AcOEt-soluble fractions of the leaf extract of Machilus konishii. Among 1 - 5, apigenin 6-C- β -dxylopyranosyl- 2 -O- β -d-glucopyranoside (2), apigenin 8-C-α-l-arabinopyranosyl-2 -O- β -d-glucopyranoside (4), and apigenin 8-C- β -d-xylopyranosyl-2 -O- β -d-glucopyranoside (5) are new. Both 4 and 5 are present as rotamer pairs. The structures of the new compounds were elucidated on the basis of NMRspectroscopic analyses and MS data. In addition, the 1H- And 13C-NMR data of apigenin 6-C- α -larabinopyranosyl- 2 -O- β -d-glucopyranoside (3) were assigned for the first time. The isolated compounds were assayed against a-glucosidase (type IV from Bacillus stearothermophilus). Kaempferol 3-O- (2-β-d-apiofuranosyl)- α -l-rhamnopyranoside (12) was found to possess the best inhibitory activity with an IC50 value of 29.3 μm.
- Lin, Yi-Shan,Lee, Shoei-Sheng
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p. 1672 - 1682
(2015/02/19)
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- A new flavonol glycoside from the aerial part of Rudbeckia laciniata
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The phytochemical investigation of Rudbeckia laciniata L. obtained a new flavonol glycoside (1), together with four flavonol glycosides (2-5) and eight quinic acid derivatives (6-13). The structure was elucidation by means of spectroscopic methods and chemical evidence. The isolated compounds were tested for cytotoxicity against four human tumor cell lines in vitro using the sulforhodamine B bioassay.
- Lee, Seung Young,Shin, Young June,Choi, Sang Un,Lee, Kang Ro
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p. 834 - 838
(2014/08/05)
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- Solvent-dependent release of bromine from bromoquercetins
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Quercetin, 6-bromoquercetin (3), and 8-bromoquercetin (4) undergo H/D exchange at 6- and 8-positions, in acetone-d6 and methanol-d 4, catalyzed by acids and bases. The base-catalyzed process is faster, and in acetone-d6 the half-lives of H-8 and H-6 are 56.5 and 48.6 h, respectively. A high regioselectivity at the position 8 of quercetin is observed under acid-catalysis in both solvents but in methanol-d4 regioselectivity is retained even under base-catalysis. On the other hand, 6,8-dibromoquercetin (2), 4 and 6,8-dibromo-2′-hydroxyquercetin (5) manifest the ability of exchanging bromine with hydrogen (or deuterium) under acid-catalysis in acetone and other enolizable ketones (e.g., methyl ethyl ketone, acetylacetone, and isophorone). These bromophenols release bromine from their 8-position only, in a slow bromination process that likely involves their protonated form (arenium ion I) as brominating agent and the enol of the above ketones as Br-acceptor. The arenium ion I of these bromophenols is expected to be a powerful electrophile and its formation is most likely to be rate-determining.
- Foti, Mario C.,Rocco, Concetta
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p. 4359 - 4365
(2014/07/22)
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- New cytotoxic cycloartane triterpene from Cassia italica aerial parts
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Phytochemical study of the aerial parts of Cassiaitalica Mill. (family: Fabaceae) growing in Saudi Arabia afforded one new cycloartane triterpene, named (22E)-3-β-hydroxycycloart-22-en-24-one (2), together with eight known compounds: β-sitosterol (1), uvaol (3), daucosterol (4), methyl 3,4-dihydroxybenzoate (5), emodin (6), 4-hydroxypheny-O-β-D-glucopyranoside (7), aloin (8) and rutin (9). The structure of the isolated compounds was determined by physical, chemical and spectral data (UV, IR, MS, 1D ( 1H, 13C and DEPT) and 2D (1H-1H COSY, HSQC and HMBC) NMR), as well as by comparing with authentic samples. Compounds 3-5 and 7-9 were isolated for the first time from the plant. Compound 2 was evaluated for its cytotoxic activity against the L5178Y and PC12 cell lines. The total methanolic extract and compounds 5-9 exhibited free radical-scavenging activity using DPPH assay.
- Mohamed, Gamal A.
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p. 976 - 983
(2014/07/21)
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- α-Rhamnosidase activity in the marine isolate Novosphingobium sp. PP1Y and its use in the bioconversion of flavonoids
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Crude protein extracts of Novosphingobium sp. PP1Y, a microorganism isolated from polluted marine waters in Pozzuoli (Italy), were analyzed for the presence of glycosidase activities. Particular attention was devoted to a α-L-rhamnosidase activity able to hydrolyze several flavonoids of interest for the pharmaceutical and food industries. This activity had an alkaline pH optimum and a moderate tolerance to the presence of organic solvents, appealing features for its possible biotechnological uses. An increase of the α-L-rhamnosidase activity in PP1Y crude extracts was induced by adding naringin to the growth medium, suggesting the possibility to use material from Citrus industrial waste to induce the glycosidase activity expressed by strain PP1Y and produce simultaneously high-added-value molecules from the hydrolysis of their flavonoids. In order to investigate on the enzymatic mechanism of PP1Y α-L-rhamnosidase activity, hydrolysis products of PNP-α-L- rhamnopyranoside were analyzed by 1H-NMR experiments. The kinetic behaviour clearly indicated an inverting mechanism of hydrolysis for this novel enzymatic activity.
- Izzo, Viviana,Tedesco, Pietro,Notomista, Eugenio,Pagnotta, Eduardo,Di Donato, Alberto,Trincone, Antonio,Tramice, Annabella
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- Regioselective solvent-phase deuteration of polyphenolic compounds informs their identification by mass spectrometry
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Liquid chromatography-mass spectrometry (LC-MS) is a highly sensitive tool for the analysis of polyphenolic compounds in complex food and beverage matrices. However, the high degree of isomerism among polyphenols in general often complicates this approach, especially for identification of novel compounds. Here, we explore the utility of mild acid-catalyzed deuterium (MACD) labeling via electrophilic aromatic substitution as a complementary method for informing polyphenolic compound structure elucidation. To prevent hydrolysis of acid-labile glycosidic linkages, optimal reaction conditions that maximize regioselective hydrogen/deuterium (H/D) exchange of aromatic protons while preserving compound integrity were characterized (60°C, pH 3.0, 72 h). Under these conditions, standard compounds varying in the number and position of hydroxyl, glycosyl, and methyl groups about their aromatic core structure produced distinguishable H/D exchange patterns. The applicability of this method for the analysis of complex mixtures was demonstrated in red wine where the extent of deuterium exchange, together with accurate mass information, led to the putative identification of an unknown compound. The identification was further supported by tandem MS (MS/MS) data, which matched conclusively to the same compound in the Metlin LC-MS/MS library. With the capacity to discriminate between select isomeric forms, MACD labeling provides structural information that complements accurate mass and tandem mass spectral measurements for informing the identification of polyphenolics by MS.
- Roe, Mikel R.,Cohen, Jerry D.,Hegeman, Adrian D.
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- Hydrolysis of the extract of rosa roxburghii tratt catalyzed by imidazolium ionic liquids
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Rosa roxburghii tratt (Cili) is a kind of fruit and medicinal plant in China, which is rich in vitamins and flavonoids. In the study, nine Bronsted acidic ionic liquids were first used as catalysts in the preparation of quercetin directly from the extract of rosa roxburghii tratt. Through rapid screening under the same reaction conditions, [PSMIM][HSO4] was found to be the best candidate catalyst. Then the sequential experiments were carried out with [PSMIM][HSO4] as catalyst. The reaction conditions were further optimized by response surface methodology and the hydrolytic dynamics was also investigated. Reusing and recovering of the ionic liquid were also studied with fairly good results. It is proved that this green catalyst is ideal for developing new hydrolysis process for crude extract of total natural flavonoids as the substitute of traditional inorganic acids.
- Yang, Chang,Zeng, Hao,Song, Hang,Yao, Shun,Ma, Hongyan
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p. 7327 - 7331
(2013/08/23)
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- Comparing the acceptor promiscuity of a Rosa hybrida glucosyltransferase RhGT1 and an engineered microbial glucosyltransferase OleDPSA toward a small flavonoid library
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Glycosylation is a widespread modification of plant secondary metabolites, and catalyzed by a superfamily of enzymes called UDP-glycosyltransferases (UGTs). UGTs are often involved in late biosynthetic steps and show broad substrate specificity or regioselectivity. In this study, the acceptor promiscuity of a Rosa hybrid UGT RhGT1 and an evolved microbial UGT OleD PSA toward a small flavonoid library was probed and compared. Interestingly, RhGT1 showed comparable acceptor promiscuity in comparison with OleDPSA, though the acceptor binding pocket of the latter is much more open and large. This clearly indicates that stabilization of the acceptor position by suitable hydrophobic interactions is important for the specificity or regioselectivity determination as well as overall fit of the acceptor into a 'big enough' binding pocket. This also poses a challenge for structure-based UGT engineering to alter the glucosylation pattern of flavonoids.
- Wang, Lu,Han, Weiqing,Xie, Chenying,Hou, Jingli,Fang, Qinghong,Gu, Jianchun,Wang, Peng George,Cheng, Jiansong
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supporting information
p. 73 - 77
(2013/03/14)
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- Flavonoids from the cocoon of Rondotia menciana
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Two flavonol glycosides along with four known flavonoids were isolated from the cocoon of the mulberry white caterpillar, Rondotia menciana (Lepidoptera: Bombycidae: Bombycinae), a closely related species of the domesticated silkworm Bombyx mori, both of which feed on leaves of mulberry (Morus alba). The two glycosides were characterized as quercetin 3-O-β-D-galactopyranosyl-(1 → 3)-β-D-galactopyranoside and kaempferol 3-O-β-D- galactopyranosyl-(1 → 3)-β-D-galactopyranoside, based on spectroscopic data and chemical evidence. The flavonol galactosides found in the cocoon were not present in the host plant, nor in the cocoon of the silkworm, B. mori. Notably, flavonol glucosides, which are the main constituents of cocoon flavonoids in B. mori mori, were not found in the R. menciana cocoon. The present result strongly suggests that R. menciana is quite unique in that they predominantly use an UDP-galactosyltransferase for conjugation of dietary flavonoids, whereas UDP-glucosyltransferases are generally used for conjugation of plant phenolics and xenobiotics in other insects.
- Hirayama, Chikara,Ono, Hiroshi,Meng, Yan,Shimada, Toru,Daimon, Takaaki
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p. 108 - 112
(2013/10/22)
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- Flavonoid constituents and biological screening of Astragalus bombycinus Boiss
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Two new flavonoid compounds were isolated from Astragalus bombycinus Boiss. and identified as quercetin-3,7-di-O-β-glucopyranoside 40-O-β-rhamnopyranoside and 5,20,40-trihydroxy-flavone-8-C-β- arabinopyranoside-7-O-β-glucopyranoside. In addition, apigenin
- Ibrahim, Lamyaa F.,Marzouk, Mona M.,Hussein, Sameh R.,Kawashty, Salwa A.,Mahmoud, Khaled,Saleh, Nabiel A.M.
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p. 386 - 393
(2013/04/23)
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- Constituents of cressa cretica L., A halophytic plant
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Three coumarins (1-3), four flavonoids (4-7) along with two phytosterols (8-9) were isolated from a halophytic plant Cressa cretica. Their structure established as coumarin (1), umbelliferone (2), daphnetin (3), quercetin (4), kaempferol (5), quercetin 3-O-β-D-glucoside (6), quercetin-3-O-α-L- rhamno-(1→6)-β-D-glucoside (7), stigmasterol (8) and β-sitosterol (9) on the basis of their comprehensive spectroscopic analysis including UV, IR, 1H NMR, 13C NMR, DART mass data.
- Sunita,Jha
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experimental part
p. 2730 - 2732
(2012/08/28)
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