| 1. |
- Ishchuk, Olena P., et al.
(författare)
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The use of polyhydroxylated carboxylic acids and lactones to diminish biofilm formation of the pathogenic yeast : Candida albicans
- 2019
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 9:19, s. 10983-10989
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Tidskriftsartikel (refereegranskat)abstract
- The vaginal microbiome of healthy women is a diverse and dynamic system of various microorganisms. Any sudden change in microbe composition can increase the vaginal pH and thus lead to vaginal infections, conditions that affect a large percentage of women each year. The most common fungal strains involved in infections belong to the yeast species Candida albicans. The main virulence factor of C. albicans is the ability to transform from planktonic yeast-form cells into a filamentous form (hyphae or pseudohyphae), with the subsequent formation of biofilm. The hyphal form, constituted by filamentous cells, has the ability to invade tissue and induce inflammation. Our hypothesis is that certain polyhydroxylated carboxylic acids, that may serve as an alternative carbohydrate source and at the same time lower the pH, function as an indicator of a nutrient-rich environment for C. albicans, which favors planktonic cells over hyphae, and thus diminish the formation of biofilm. We have shown that the biofilm formation in C. albicans and other Candida species can be significantly reduced by the addition of glucono-δ-lactone (GDL).
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| 2. |
- Lozano, Maribel, et al.
(författare)
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Cytotoxicity of New Damsin Derivatives in Breast Cancer Cells
- 2019
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Ingår i: Journal of Pharmacy & Drug Development. - 2348-9782. ; 1:2
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Tidskriftsartikel (refereegranskat)abstract
- As a follow-up of a previous investigation in which semisynthetic damsin derivatives were shown to possess up to 10 times higher cytoxicity in JIMT-1 breast cancer cells compared to normal breast epithelial MCF-10A cells, a range of new derivatives were prepared and assayed toward the same cells. Damsin, a natural plant metabolite containing a α-methylene-γ-lactone (or 3-methylenedihydro- furan-2(3H)-one) moiety, was modified in position 3 by Claisen-Schmidt condensations with aromatic aldehydes, mainly mono- or disubstituted benzaldehydes, without affecting the α-methylene-γ-lactone function. This lactone ring is a Michael acceptor that is known to affect biological processes such as cell proliferation, death/apoptosis, and cell migration, by interfering with nucleophilic sites in cell signalling pathways. However, although Michael acceptors are reactive, the Michael addition is reversible and it can be assumed that also other parts of the molecules will moderate the binding to and the release from any given nucleophilic site in a protein, and thereby moderate a specific biological activity. In this investigation, the cytotoxicity of 20 α-methylene-γ-lactones towards normal breast epithelial MCF-10A cells as well as breast cancer JIMT-1 cells is compared, by determining the inhibitory concentration 50 (IC50) from dose response curves. The IC50 values in the two cell lines were found to depend on the overall structure of the assayed compounds, although less in this subset of compounds compared to a previous investigation. Structure-activity relationships that may explain the observed differences in potency and selectivity are discussed.
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| 3. |
- Lozano, Maribel, et al.
(författare)
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Selective Cytotoxicity of Damsin Derivatives in Breast Cancer Cells
- 2019
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Ingår i: Journal of Advanced Pharmaceutical Science and Technology. - : Open Access Pub. - 2328-0182. ; 2:1, s. 23-37
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Tidskriftsartikel (refereegranskat)abstract
- Cancer is the leading cause of death worldwide, and there is a constant need for new treatmentstrategies. Sesquiterpene lactones containing a 3-methylenedihydrofuran-2(3H)-one (or α-methylene-γ-lactone) moiety, for example damsin (1), are Michael acceptors that affect biological processes such as cell proliferation, death/apoptosis, and cell migration, by interfering with cell signalling pathways. Although the reactivity of the α-methylene-γ-lactone moiety is important for these effects, the Michael addition is reversible and it can be assumed that also other parts of the molecules will moderate any given biological activity. In this investigation, the cytotoxicity of 23 α-methylene-γ-lactones towards normal breast epithelial MCF-10A cells as well as breast cancer JIMT-1 cells is compared. Most of the investigated compounds are semisynthetic derivatives prepared by the condensation of the natural product damsin (1) with aldehydes. The two cell lines were treated with various concentrations of the compounds in dose response assays, and the 50 % inhibitory concentration (IC50) was determined from dose response curves. The IC50 values were found to depend strongly on the overall structure. The ratio between the IC50 values for MCF-10A and JIMT-1 cells, as a measure for the selectivity of a compound to kill cancer cells, was calculated, and found to vary between just over 1 to more than 10. The most potent derivatives formed from the condensation of 1 with aromatic aldehydes towards JIMT-1 cells are 3a and 3i, both with ratios between the IC50 values for MCF-10A and JIMT-1 cells close to 5. Also some aldol condensation products with acyclic aldehydes, i.e. 3r and 3u, were equally potent, and the latter showed the highest selectivity (ratio > 10). Structure-activity relationships that may explain the observed differences in potency and selectivity are discussed.
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| 4. |
- Siegbahn, Anna, et al.
(författare)
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Exploration of the active site of beta 4GalT7 : modifications of the aglycon of aromatic xylosides
- 2015
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Ingår i: Organic and biomolecular chemistry. - : Royal Society of Chemistry (RSC). - 1477-0520 .- 1477-0539. ; 13:11, s. 3351-3362
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Tidskriftsartikel (refereegranskat)abstract
- Proteoglycans (PGs) are macromolecules that consist of long linear polysaccharides, glycosaminoglycan (GAG) chains, covalently attached to a core protein by the carbohydrate xylose. The biosynthesis of GAG chains is initiated by xylosylation of the core protein followed by galactosylation by the galactosyltransferase beta 4GalT7. Some beta-D-xylosides, such as 2-naphthyl beta-D-xylopyranoside, can induce GAG synthesis by serving as acceptor substrates for beta 4GalT7 and by that also compete with the GAG synthesis on core proteins. Here we present structure-activity relationships for beta 4GalT7 and xylosides with modifications of the aromatic aglycon, using enzymatic assays, cell studies, and molecular docking simulations. The results show that the aglycons reside on the outside of the active site of the enzyme and that quite bulky aglycons are accepted. By separating the aromatic aglycon from the xylose moiety by linkers, a trend towards increased galactosylation with increased linker length is observed. The galactosylation is influenced by the identity and position of substituents in the aromatic framework, and generally, only xylosides with beta-glycosidic linkages function as good substrates for beta 4GalT7. We also show that the galactosylation ability of a xyloside is increased by replacing the anomeric oxygen with sulfur, but decreased by replacing it with carbon. Finally, we propose that reaction kinetics of galactosylation by beta 4GalT7 is dependent on subtle differences in orientation of the xylose moiety.
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| 5. |
- Siegbahn, Anna, et al.
(författare)
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Exploration of the active site of β4GalT7: modifications of the aglycon of aromatic xylosides.
- 2015
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Ingår i: Organic and Biomolecular Chemistry. - : Royal Society of Chemistry (RSC). - 1477-0539 .- 1477-0520. ; 13:11, s. 3351-3362
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Tidskriftsartikel (refereegranskat)abstract
- Proteoglycans (PGs) are macromolecules that consist of long linear polysaccharides, glycosaminoglycan (GAG) chains, covalently attached to a core protein by the carbohydrate xylose. The biosynthesis of GAG chains is initiated by xylosylation of the core protein followed by galactosylation by the galactosyltransferase β4GalT7. Some β-d-xylosides, such as 2-naphthyl β-d-xylopyranoside, can induce GAG synthesis by serving as acceptor substrates for β4GalT7 and by that also compete with the GAG synthesis on core proteins. Here we present structure-activity relationships for β4GalT7 and xylosides with modifications of the aromatic aglycon, using enzymatic assays, cell studies, and molecular docking simulations. The results show that the aglycons reside on the outside of the active site of the enzyme and that quite bulky aglycons are accepted. By separating the aromatic aglycon from the xylose moiety by linkers, a trend towards increased galactosylation with increased linker length is observed. The galactosylation is influenced by the identity and position of substituents in the aromatic framework, and generally, only xylosides with β-glycosidic linkages function as good substrates for β4GalT7. We also show that the galactosylation ability of a xyloside is increased by replacing the anomeric oxygen with sulfur, but decreased by replacing it with carbon. Finally, we propose that reaction kinetics of galactosylation by β4GalT7 is dependent on subtle differences in orientation of the xylose moiety.
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| 6. |
- Thorsheim, Karin, et al.
(författare)
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Chemistry of xylopyranosides
- 2015
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Ingår i: Carbohydrate Research. - : Elsevier BV. - 0008-6215 .- 1873-426X. ; 418, s. 65-88
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Forskningsöversikt (refereegranskat)abstract
- Xylose is one of the few monosaccharidic building blocks that are used by mammalian cells. In comparison with other monosaccharides, xylose is rather unusual and, so far, only found in two different mammalian structures, i.e. in the Notch receptor and as the linker between protein and glycosaminoglycan (GAG) chains in proteoglycans. Interestingly, simple soluble xylopyranosides can not only initiate the biosynthesis of soluble GAG chains but also function as inhibitors of important enzymes in the biosynthesis of proteoglycans. Furthermore, xylose is a major constituent of hemicellulosic xylans and thus one of the most abundant carbohydrates on Earth. Altogether, this has spurred a strong interest in xylose chemistry. The scope of this review is to describe synthesis of xylopyranosyl donors, as well as protective group chemistry, modifications, and conformational analysis of xylose.
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| 7. |
- Thorsheim, Karin, et al.
(författare)
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Expanding the scope of methyl xanthate esters - From Barton-McCombie reaction auxiliary to versatile protective group
- 2017
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Ingår i: Tetrahedron. - : Elsevier BV. - 0040-4020. ; 73:44, s. 6329-6333
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Tidskriftsartikel (refereegranskat)abstract
- The methyl xanthate ester is presented as a versatile protective group for alcohols. Hydroxyl groups can easily be transformed into methyl xanthate esters by several methods and are commonly used as an auxiliary in the Barton-McCombie reaction. We show that these methyl xanthate esters can readily and chemoselectively be cleaved under mild conditions by the action of diethylenetriamine using microwave heating. This method is orthogonal to many common hydroxyl protective groups that can be introduced and cleaved in the presence of methyl xanthate ester.
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| 8. |
- Thorsheim, Karin, et al.
(författare)
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Naphthyl Thio- and Carba-xylopyranosides for Exploration of the Active Site of ß-1,4-Galactosyltransferase 7 (ß4GalT7)
- 2017
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Ingår i: Chemistry - A European Journal. - : Wiley. - 0947-6539 .- 1521-3765. ; 23:71, s. 18057-18065
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Tidskriftsartikel (refereegranskat)abstract
- Xyloside analogues with substitution of the endocyclic oxygen atom by sulfur or carbon were investigated as substrates for -1,4-galactosyltransferase7 (4GalT7), a key enzyme in the biosynthesis of glycosaminoglycan chains. The analogues with an endocyclic sulfur atom proved to be excellent substrates for 4GalT7, and were galactosylated approximately fifteen times more efficiently than the corresponding xyloside. The 5a-carba--xylopyranoside in the d-configuration proved to be a good substrate for 4GalT7, whereas the enantiomer in the l-configuration showed no activity. Further investigations by X-ray crystallography, NMR spectroscopy, and molecular modeling provided a rationale for the pronounced activity of the sulfur analogues. Favorable - interactions between the 2-naphthyl moiety and a tyrosine side chain of the enzyme were observed for the thio analogues, which open up for the design of efficient GAG primers and inhibitors.
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| 9. |
- Willén, Daniel, et al.
(författare)
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Synthesis of Double-Modified Xyloside Analogues for Probing the β4GalT7 Active Site
- 2018
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Ingår i: Journal of Organic Chemistry. - : American Chemical Society (ACS). - 0022-3263 .- 1520-6904. ; 83:3, s. 1259-1277
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Tidskriftsartikel (refereegranskat)abstract
- Monosubstituted naphthoxylosides have been shown to function as substrates for, and inhibitors of, the enzyme β4GalT7, a key enzyme in the biosynthetic pathway leading to glycosaminoglycans and proteoglycans. In this article, we explore the synthesis of 16 xyloside analogues, modified at two different positions, as well as their function as inhibitors of and/or substrates for the enzyme. Seemingly simple compounds turned out to require complex synthetic pathways. A meta-analysis of the synthetic work shows that, regardless of the abundance of methods available for carbohydrate synthesis, even simple modifications can turn out to be problematic, and double modifications present additional challenges due to conformational, steric, and stereoelectronic effects.
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