Glycosidic Moiety Research Articles

Visual sensing of proteins using gold nanoparticles coated with polyphenolic glycoside

Gold nanoparticles combined with a polyphenolic glycoside (α-glucosylrutin) were prepared and applied for the selective detection of proteins. Glucosylrutin was coated onto gold nanoparticles with a particle size of 40 nm, without aggregates and color changes. The glucosylrutin-coated gold surface was preferentially adsorbed with concanavalin A, which has specificity against glucosides and mannosides. When the glucosylrutin-coated gold nanoparticles were mixed with concanavalin A, the color of the dispersion changed from red to reddish violet. The level of chromatic change was dependent on the concentration of concanavalin A. When other proteins (bovine serum albumin and peanut agglutinin) were added to the dispersion, no color change was observed. The molecular recognition site for detection of concanavalin A was the glycoside moiety, because the catechin-coated gold nanoparticles have no function in the detection of concanavalin A. Urchin-shaped glucosylrutin-coated gold nanoparticles were also useful for the visual sensing of concanavalin A.

Green Production and Structural Evaluation of Maize Starch–Fatty Acid Complexes Through High Speed Homogenization

The current study describes the production of maize starch–fatty acid complexes through high speed homogenization, a novel field of research, without heat or any chemical treatment. The starch–fatty acid complexes were produced with three different fatty acids, i.e. stearic acid (T1), palmitic acid (T2) and lauric acid (T3). The complexes were analyzed through various techniques. The results reveal that the complexing index (CI), swelling power (SP) and solubility (S) for T1 were significantly higher compared to T2 and T3. In X-ray diffraction (XRD) studies, relatively lower crystalline (V-type pattern) structures were obtained for the samples T1–T3, where T2 showed the highest crystallinity amongst all. Fourier transformed infrared (FTIR) spectra showed characteristic bands i.e., OH, C=O, C–O and long-chain CH2 functionalities thus confirming the overall incorporation of acids into glycoside moieties. The Scanning electron microscopy (SEM) analysis showed sub-crystalline matrix structures with fewer or no spherulites indicating the overall incorporation of acids in starch. The samples showed relatively low thermal stability in the thermal gravimetric analysis (TGA) in the range of 180 to 280 °C. These results suggest that high speed homogenization had the potential for the development of green and biocompatible maize starch–fatty acid complexes.

Bioinspired oxidation in cytochrome P450 of isomers orientin and isoorientin using Salen complexes.

Orientin and isoorientin are C-glycosidic flavonoids, considered as markers of some plant species such as Passiflora edulis var. flavicarpa Degener, and reported in the literature to have pharmacological properties. In order to evaluate and characterize the in vitro metabolism of these flavonoids, phase I biotransformation reactions were simulated using Salen complexes. These flavonoids were oxidized separately in biomimetic reactions in different proportions, using one oxidant, m-chloroperbenzoic acid or iodosylbenzene, and one catalyst, the Jacobsen catalyst or [Mn(3-MeOSalen)Cl]. The [Mn(3-MeOSalen)Cl] catalyst was synthesized and characterized using spectrometric techniques. The oxidation potentials of the catalysts were compared. All reactions were monitored and analyzed using ultrahigh-performance liquid chromatography diode-array detection (UHPLC-DAD) and high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS). The analysis by UHPLC-DAD and HPLC/MS/MS showed that isoorientin produces more products than orientin and that [Mn(3-MeOSalen)Cl] produces more products than the Jacobsen catalyst. In addition, [Mn(3-MeOSalen)Cl], which has a higher oxidation potential, formed products with the addition of one or two atoms of oxygen, while the Jacobsen catalyst formed compounds with only one added oxygen atom. The products with the addition of one oxygen atom were mainly epoxides, while those with two added oxygens formed an epoxide in the C-ring and incorporated the other oxygen into the glycosidic moiety. The formation of epoxides is common in biomimetic reactions and they may represent a safety risk in medicinal products due to their high reactivity. This study may serve as a basis for subsequent pharmacological and toxicological studies that investigate the presence of these compounds as phase I metabolites, and ensure the safe use of plant products containing orientin as a chemical marker.

Unique Microbial Catabolic Pathway for the Human Core N-Glycan Constituent Fucosyl-α-1,6-N-Acetylglucosamine-Asparagine.

The survival of commensal bacteria in the human gut partially depends on their ability to metabolize host-derived molecules. The use of the glycosidic moiety of N-glycoproteins by bacteria has been reported, but the role of N-glycopeptides or glycoamino acids as the substrates for bacterial growth has not been evaluated. We have identified in Lactobacillus casei strain BL23 a gene cluster (alf-2) involved in the catabolism of the glycoamino acid fucosyl-α-1,6-N-GlcNAc-Asn (6'FN-Asn), a constituent of the core-fucosylated structures of mammalian N-glycoproteins. The cluster consists of the genes alfHC, encoding a major facilitator superfamily (MFS) permease and the α-l-fucosidase AlfC, and the divergently oriented asdA (aspartate 4-decarboxylase), alfR2 (transcriptional regulator), pepV (peptidase), asnA2 (glycosyl-asparaginase), and sugK (sugar kinase) genes. Knockout mutants showed that alfH, alfC, asdA, asnA2, and sugK are necessary for efficient 6'FN-Asn utilization. The alf-2 genes are induced by 6'FN-Asn, but not by its glycan moiety, via the AlfR2 regulator. The constitutive expression of alf-2 genes in an alfR2 strain allowed the metabolism of a variety of 6'-fucosyl-glycans. However, GlcNAc-Asn did not support growth in this mutant background, indicating that the presence of a 6'-fucose moiety is crucial for substrate transport via AlfH. Within bacteria, 6'FN-Asn is defucosylated by AlfC, generating GlcNAc-Asn. This glycoamino acid is processed by the glycosylasparaginase AsnA2. GlcNAc-Asn hydrolysis generates aspartate and GlcNAc, which is used as a fermentable source by L.casei These data establish the existence in a commensal bacterial species of an exclusive metabolic pathway likely to scavenge human milk and mucosal fucosylated N-glycopeptides in the gastrointestinal tract.IMPORTANCE The gastrointestinal tract accommodates more than 1014 microorganisms that have an enormous impact on human health. The mechanisms enabling commensal bacteria and administered probiotics to colonize the gut remain largely unknown. The ability to utilize host-derived carbon and energy resources available at the mucosal surfaces may provide these bacteria with a competitive advantage in the gut. Here, we have identified in the commensal species Lactobacillus casei a novel metabolic pathway for the utilization of the glycoamino acid fucosyl-α-1,6-N-GlcNAc-Asn, which is present in the core-fucosylated N-glycoproteins from mammalians. These results give insight into the molecular interactions between the host and commensal/probiotic bacteria and may help to devise new strategies to restore gut microbiota homeostasis in diseases associated with dysbiotic microbiota.

In Situ/Subcellular Localization of Arabinogalactan Protein Expression by Fluorescent In Situ Hybridization (FISH).

The arabinogalactan proteins are highly glycosylated and ubiquitous in plants. They are involved in several aspects of plant development and reproduction; however, the mechanics behind their function remains for the most part unclear, as the carbohydrate moiety, covering the most part of the protein core, is poorly characterized at the individual protein level. Traditional immunolocalization using antibodies that recognize the glycosidic moiety of the protein cannot be used to elucidate individual proteins' distribution, function, or interactors. Indirect approaches are typically used to study these proteins, relying on reverse genetic analysis of null mutants or using a reporter fusion system. In the method presented here, we propose the use of RNA probes to assist in the localization of individual AGPs expression/mRNAs in tissues of Arabidopsis by fluorescent in situ hybridization, FISH. An extensive description of all aspects of this technique is provided, from RNA probe synthesis to the hybridization, trying to overcome the lack of specific antibodies for the protein core of AGPs.

A comparison of the absorption and metabolism of the major quercetin in brassica, quercetin-3-O-sophoroside, to that of quercetin aglycone, in rats

Although flavonoid sophorosides are common glycosides in brassica vegetables, red raspberries and other food plants, there is a lack of studies of absorption and metabolism of any sophoroside. The aim of this study was to characterize the absorption, phase II metabolism and microbial catabolism of quercetin-3-O-sophoroside, compared to that of quercetin aglycone. Quercetin-3-O-sophoroside was purified from Apocynum venetum and characterized by MS2, 1H and 13C NMR. Using an in situ rat gut model, we found intact, methylated, sulfated and both methylated and sulfated quercetin sophoroside in the plasma following jejunal introduction of the sophoroside; we found derivatives of benzoic acid, phenylacetic acid, and phenyl propionic acid in the cecal contents following cecal introduction. This novel finding, that quercetin sophoroside was absorbed intact, without deglycosylation, points to a possible role for the terminal sugar and/or the type of linkage among glycosidic moieties in the mechanism of absorption of flavonoid glycosides.

New HSV-1 Anti-Viral 1'-Homocarbocyclic Nucleoside Analogs with an Optically Active Substituted Bicyclo[2.2.1]Heptane Fragment as a Glycoside Moiety.

New 1′-homocarbanucleoside analogs with an optically active substituted bicyclo[2.2.1]heptane skeleton as sugar moiety were synthesized. The pyrimidine analogs with uracil, 5-fluorouracil, thymine and cytosine and key intermediate with 6-chloropurine (5) as nucleobases were synthesized by a selective Mitsunobu reaction on the primary hydroxymethyl group in the presence of 5-endo-hydroxyl group. Adenine and 6-substituted adenine homonucleosides were obtained by the substitution of the 6-chlorine atom of the key intermediate 5 with ammonia and selected amines, and 6-methoxy- and 6-ethoxy substituted purine homonucleosides by reaction with the corresponding alkoxides. No derivatives appeared active against entero, yellow fever, chikungunya, and adeno type 1viruses. Two compounds (6j and 6d) had lower IC50 (15 ± 2 and 21 ± 4 µM) and compound 6f had an identical value of IC50 (28 ± 4 µM) to that of acyclovir, suggesting that the bicyclo[2.2.1]heptane skeleton could be further studied to find a candidate for sugar moiety of the nucleosides.

Antioxidant capacity and hepatoprotective activity of myristic acid acylated derivative of phloridzin

The antioxidant activities in vitro and hepatoprotective effects against carbon tetrachloride (CCl4) induced acute liver injury in vivo of myristic acid acylated derivative of phloridzin (PZM) were investigated. The PZM was obtained by enzymatic acylation of myristic acid and phloridzin (PZ). The antioxidant capability of PZM in vitro was evaluated by the ferric reducing antioxidant power assay (FRAP), 2,2′-Azinobis- 3-ethylbenzthiazoline-6-sulphonate (ABTS+·) and 2,2-diphenyl-1-picrylhydrazyl (DPPH·) radical scavenging assay. Mice were intragastrically treated with control or PZM (20, 40, and 80 mg/kg) for 5 days and intra-peritoneal injection with CCl4. The enzymatic acylated synthesis of myristic acid and phloridzin was region-selective taken place on 6″-OH of phloridzin glycoside moiety and achieved 93% yield. PZM had a significantly higher total antioxidant ability, same scavenging ABTS+· ability and weaker scavenging DPPH· ability when compared to the parent PZ. The of aminotransferase serum activity and malondialdehyde hepatic activity were elevated (P < 0.015) after treatment with CCl4, while the related liver enzymatic activities and glutathione concentration were lower. These changes were enhanced by PZM. Further studies showed that PZM reduced the interleukin-6 expression and stimulated liver regeneration caused by CCl4. PZM attained good antioxidant capacity in vitro and had excellent hepatoprotective effects in vivo and better bioactivity compared to the parent phloridzin. The significance of hepatoprotective effect of phloridzin derivative against CCl4-induced hepatotoxicity in mice is an important and new finding.

New flavonoid glycosides conjugates: synthesis, characterization, and evaluationof their cytotoxic activities

A series of novel halogenated 3-hydroxyflavones (3HFs) were prepared by reacting halogenated hydroxyacetophenones with the appropriate aromatic aldehyde. Glycosylation of 3HFs with acetobromoglucose and deprotection of the acetyl protective groups afforded the desired 3-$O$-flavonoids glycosides in satisfactory yields. All the prepared compounds were tested for their cytotoxic activity against HCT-116, MCF-7, and OVCAR-3 human cancer cell lines. The 3HFs exhibited higher cytotoxic activities compared with the glycosylated flavonoids. Overall, the structure-activity relationship study showed that the introduction of glycoside moiety at the C-3 OH position does not improve the bioactivity.

Hypoculoside, a sphingoid base-like compound from Acremonium disrupts the membrane integrity of yeast cells

We have isolated Hypoculoside, a new glycosidic amino alcohol lipid from the fungus Acremonium sp. F2434 belonging to the order Hypocreales and determined its structure by 2D-NMR (Nuclear Magnetic Resonance) spectroscopy. Hypoculoside has antifungal, antibacterial and cytotoxic activities. Homozygous profiling (HOP) of hypoculoside in Saccharomyces cerevisiae (budding yeast) revealed that several mutants defective in vesicular trafficking and vacuolar protein transport are sensitive to hypoculoside. Staining of budding yeast cells with the styryl dye FM4-64 indicated that hypoculoside damaged the vacuolar structure. Furthermore, the propidium iodide (PI) uptake assay showed that hypoculoside disrupted the plasma membrane integrity of budding yeast cells. Interestingly, the glycosidic moiety of hypoculoside is required for its deleterious effect on growth, vacuoles and plasma membrane of budding yeast cells.

Dynamic changes in flavonol glycosides during production of green, yellow, white, oolong and black teas from Camellia sinensis L. (cv. Fudingdabaicha)

SummaryFlavonol glycosides with low thresholds are important flavour substances in tea leaves. This study monitored the dynamic changes in flavonol glycosides during the production of different teas. The fresh leaves of cv. Fudingdabaicha with 15.77 mg g−1 of total flavonol glycosides (TFG) were respectively processed into green, yellow, white, oolong and black teas. A reduction of TFG was observed for different teas, amongst which black tea contained the lowest level of TFG (9.83 mg g−1), followed by oolong tea (11.96 mg g−1), while green, yellow and white teas contained similar levels of TFG (~13.70 mg g−1). Fixation was crucial to maintain the stability of flavonol glycosides due to its inactivation effect on enzymes at high temperature. Principal component analysis results indicated that flavonol glycosides were vulnerable to fermentation, and the stabilities of flavonol glycosides were related with aglycone and glycoside moiety.

DIABETES MELLITUS: A REVIEW WITH EDGE OF SGLT2 INHIBITORS

The relative (Type 2 DM) or absolute (Type 1 DM) deficiency of insulin hormone could result into hyperglycemia, which is a characteristic feature of diabetes mellitus. Diabetes mellitus is a leading cause of morbidity and mortality because of its associated complications viz. Neuropathy, Nephropathy, Retinopathy, Cardiovascular disorders.The feature which has to be noted down is the death of individuals before the age of 70 y, which is attributable to high blood glucose levels. According to WHO diabetes mellitus will be the seventh leading cause of deaths till 2030.The induction of glycosuria as meant for gly­caemiac control in patients with DM is an extension of the physiological role of renal TmG to curb the menace of hyperglycemia. The first biologically derived SGLT2 inhibitor phlorizin, isolated in 1835 from the root bark of apple tree, was not developed as an antihyperglycaemic drug because of rapid degradation by lactase-phlorizin hydrolase and poor absorption from the gastrointestinal tract. Other glycoside moieties derived from phlorizin struc­ture have subsequently been developed recently.

Synthesis and studies molecular docking of some new thioxobenzo[g]pteridine derivatives and 1,4-dihydroquinoxaline derivatives with glycosidic moiety

ABSTRACTThe present work is mainly dedicated to heterocyclic compounds as well as S-glycoside. 1,4-dihydroquinoxaline derivatives 3 were obtained from the reaction 2 with carbon disulfide in presence of potassium hydroxide. S-glycoside 4 was prepared from the reaction of compound 3 with 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide. Several heterocyclic derivatives containing thioxobenzo[g]pteridine ring systems were obtained starting from ethyl 3-amino-1,4-dihydroquinoxaline-2-carboxylate 1. These newly synthesized compounds were docked within the active site of cyclooxygenase-2 (COX-2). The results of this docking study revealed that the new compounds might exhibit good anti-inflammatory activity. The structure of new compounds was demonstrated by elemental analysis, IR, 1H NMR spectra and mass spectra.

Synthesis of New Glycosylated Flavonoids with Inhibitory Activity on Cell Growth.

Natural flavonoids and xanthone glycosides display several biological activities, with the glycoside moiety playing an important role in the mechanism of action of these metabolites. Herein, to give further insights into the inhibitory activity on cell growth of these classes of compounds, the synthesis of four flavonoids (5, 6, 9, and 10) and one xanthone (7) containing one or more acetoglycoside moieties was carried out. Acetyl groups were introduced using acetic anhydride and microwave irradiation. The introduction of one or two acetoglycoside moieties in the framework of 3,7-dihydroxyflavone (4) was performed using two synthetic methods: the Michael reaction and the Koenigs-Knorr reaction. The in vitro cell growth inhibitory activity of compounds 5, 6, 7, 9, and 10 was investigated in six human tumor cell lines: A375-C5 (malignant melanoma IL-1 insensitive), MCF-7 (breast adenocarcinoma), NCI-H460 (non-small cell lung cancer), U251 (glioblastoma astrocytoma), U373 (glioblastoma astrocytoma), and U87MG (glioblastoma astrocytoma). The new flavonoid 3-hydroxy-7-(2,3,4,6-tetra-O-acetyl-β-glucopyranosyl) flavone (10) was the most potent compound in all tumor cell lines tested, with GI50 values < 8 μM and a notable degree of selectivity for cancer cells.

UV–Vis spectroscopy combined with chemometric study on the interactions of three dietary flavonoids with copper ions

The complex formation between a copper ion and the dietary flavonoid quercetin (QU) and its two glycosides hyperin (HY) and rutin (RU) was studied by the combined use of spectroscopic measurement and the chemometric method. The spectral changes of pH titration revealed two successively formed deprotonated species of QU: the first formed species was proposed to be the 3-hydroxyl group deprotonated QU, and the second was the quinone form QU, which was formed by oxidation after the hydroxyl groups in the B-ring were deprotonated at high pH values. Similar results were obtained for HY and RU with two deprotonated species forming at high pH values. UV/visible spectroscopy showed successive formation of CuL2 and CuL species of QU at pH 6.0, while only Cu2L was formed for HY and RU at this pH. Glycoside moieties in the C-ring of flavonoids decrease the conditional associated constants between flavonoids and Cu2+.

P-244 - Non-enzymatic oxidation of ganglioside studied by mass spectrometry: Gm1 as a case study

Gangliosides are acidic glycosphingolipids (GLS) found in cells membrane, lipid raft domains, and are particularly abundant in central nervous systems, where they play important roles. Alteration in gangliosides has been correlated with the development of diseases, such as neurodegenerative diseases, and inflammation, usually associated with oxidative stress. However, knowledge regarding oxidation of gangliosides is scarce. In this study we evaluated the effect of radical oxidation in GM1 (Neu5Acα2–3 (Galβ1–3GalNAcβ1–4) Galβ1–4Glcβ1Cer) under Fenton reaction conditions, using ESI-MS and MS/MS. Oxidation of GM1 yield a plethora of product including oxygenated GM1 and several GLS formed due to oxidative decomposition of the glycosidic moiety, leading to the formation of other gangliosides:GM2, GM3, asialo-GM1, asialo-GM; small GSL as LacCer, GalCer and ceramides. Non-enzymatic oxidation of GM1 under oxidative stress contributes to the generation of other gangliosides that may participate in the imbalance of gangliosides metabolism in vivo, through uncontrolled enzymatic pathways and, consequently, play some role in neurodegenerative processes.

Discovery of Glycosylated Genipin Derivatives as Novel Antiviral, Insecticidal, and Fungicidal Agents.

A series of novel genipin glycoside derivatives incorporating 11 glycosidic moieties at either the 1 or 10 position of genipin were designed and synthesized. These compounds exhibited moderate to excellent inhibitory activities against tobacco mosaic virus. Especially, the in vitro and in vivo activities of compounds 6e, 7c, 7d, 7f, 7h, and 7i were comparable to that of ribavirin. In particular, compound 7c, the mannosyl derivative of genipin at the 10 position, showed the best activity. The series of genipin glycosyl derivatives also displayed fungicidal activities against 14 kinds of phytopathogenic fungi, especially for Rhizoctonia cerealis and Sclerotinia sclerotiorum. Moreover, compound 6h exhibited good insecticidal activity against diamondback moth; compounds 7b, 7c, and 7g exhibited moderate insecticidal activity against three kinds of Lepidoptera pests (oriental armyworm, cotton bollworm, and corn borer); and compound 7e showed excellent larvacidal activities against mosquito.

Glycoalkaloid composition explains variation in slug resistance in Solanum dulcamara

In natural environments, plants have to deal with a wide range of different herbivores whose communities vary in time and space. It is believed that the chemical diversity within plant species has mainly arisen from selection pressures exerted by herbivores. So far, the effects of chemical diversity on plant resistance have mostly been assessed for arthropod herbivores. However, also gastropods, such as slugs, can cause extensive damage to plants. Here we investigate to what extent individual Solanum dulcamara plants differ in their resistance to slug herbivory and whether this variation can be explained by differences in secondary metabolites. We performed a series of preference assays using the grey field slug (Deroceras reticulatum) and S. dulcamara accessions from eight geographically distinct populations from the Netherlands. Significant and consistent variation in slug preference was found for individual accessions within and among populations. Metabolomic analyses showed that variation in steroidal glycoalkaloids (GAs) correlated with slug preference; accessions with high GA levels were consistently less damaged by slugs. One, strongly preferred, accession with particularly low GA levels contained high levels of structurally related steroidal compounds. These were conjugated with uronic acid instead of the glycoside moieties common for Solanum GAs. Our results illustrate how intraspecific variation in steroidal glycoside profiles affects resistance to slug feeding. This suggests that also slugs should be considered as important drivers in the co-evolution between plants and herbivores.

Mechanism study of selected phenolic compounds determination using β-cyclodextrin-coated CdSe/ZnS quantum dots

β-Cyclodextrin (βCD)-coated CdSe/ZnS quantum dots (QDs), provide a sensitive method for the determination of phenolic compounds. The current study aimed to explain the mechanisms involved in photoluminescence quenching of CdSe/ZnS QDs, during the determination of quercetin and gallic acid, and select derivatives thereof. Quercetin, quercetin glycosides, gallic acid and gallate esters, were investigated to understand how the glycoside moiety in glycosides and the hydrocarbon chain in esters, affect the interactions of the investigated polyphenols with βCD-coated QDs. The phenomenon of βCD-coated CdSe/ZnS photoluminescence quenching, is caused by the effective formation of host-guest inclusion complexes between polyphenols and βCD. The presence of the glycoside moiety in the quercetin molecule reduced the effectiveness of the complex formation, while, in contrast, the efficiency of complexation increased with increasing hydrocarbon chain length of the gallate ester molecule. QD photoluminescence quenching may be a consequence of the proximity between the interacting phenolic compounds with the QD surface, rather than βCDs peeling off from the QD surface, resulting in structural destabilization. From the thermodynamic parameters, it was concluded that the formation of the complexes is based both on the van der Waals interactions forces and hydrophobic interactions between guest and host molecules. Ionic interactions may also play an important role in the effectiveness of polyphenol-βCD inclusion complex formation. In order to obtain QDs with long-term stability, there is a need to increase the zeta potential value of the QD surface. Recognition of the above-described mechanisms, should enable the optimization of existing methods and the development of new applications of βCD-coated CdSe/ZnS QDs, such as determination of octyl gallate in foodstuffs.

Glycosylated Flavonoids from Psidium guineense as Major Inhibitors of HIV-1 Replication in vitro

Flavonoids are present in practically all plants and many biological activities have been described for them. The flavonoid quercetin is a common molecule for which anti-HIV activity has been demonstrated. Avicularin and guajaverin are derivatives of quercetin with a glycoside substituent in their structure. In this work, a mixture of both derivatives was purified from an extract of Psidium guinense. The mixture exhibited activity against HIV-1 in vitro, with an IC50 of approximately 8.5 μg/mL, which compares favorably with the IC50 of 53 μg/mL of quercetin. The mixture also inhibited HIV-1 reverse transcriptase (RT), with an IC50 of 7.2 μM, compared to 0.6 μM for quercetin. These results are in agreement with the in silico prediction for the interaction of these flavonoids with RT and suggest that the glycosylic moiety could favor the transport of the compound into the cell. However, the glycosidic moiety might be cleaved intracellularly, being the resultant quercetin responsible for the antiviral activity.