1.
Tjondro, Harry C., et al.
(författare)
Hyper-truncated Asn355- And Asn391-glycans modulate the activity of neutrophil granule myeloperoxidase
2021
Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 296
Tidskriftsartikel (refereegranskat) abstract
Myeloperoxidase (MPO) plays essential roles in neutrophil-mediated immunity via the generation of reactive oxidation products. Complex carbohydrates decorate MPO at discrete sites, but their functional relevance remains elusive. To this end, we have characterised the structure–biosynthesis–activity relationship of neutrophil MPO (nMPO). Mass spectrometry demonstrated that nMPO carries both characteristic under-processed and hyper-truncated glycans. Occlusion of the Asn355/Asn391-glycosylation sites and the Asn323-/Asn483-glycans, located in the MPO dimerisation zone, was found to affect the local glycan processing, thereby providing a molecular basis of the site-specific nMPO glycosylation. Native mass spectrometry, mass photometry and glycopeptide profiling revealed significant molecular complexity of diprotomeric nMPO arising from heterogeneous glycosylation, oxidation, chlorination and polypeptide truncation variants and a previously unreported low-abundance monoprotomer. Longitudinal profiling of maturing, mature, granule-separated and pathogen-stimulated neutrophils demonstrated that nMPO is dynamically expressed during granulopoiesis, unevenly distributed across granules and degranulated upon activation. We also show that proMPO-to-MPO maturation occurs during early/mid-stage granulopoiesis. While similar global MPO glycosylation was observed across conditions, the conserved Asn355-/Asn391-sites displayed elevated glycan hyper-truncation, which correlated with higher enzyme activities of MPO in distinct granule populations. Enzymatic trimming of the Asn355-/Asn391-glycans recapitulated the activity gain and showed that nMPO carrying hyper-truncated glycans at these positions exhibits increased thermal stability, polypeptide accessibility and ceruloplasmin-mediated inhibition potential relative to native nMPO. Finally, molecular modelling revealed that hyper-truncated Asn355-glycans positioned in the MPO-ceruloplasmin interface are critical for uninterrupted inhibition. Here, through an innovative and comprehensive approach, we report novel functional roles of MPO glycans, providing new insight into neutrophil-mediated immunity.
2.
Deyou, Tsegaye, et al.
(författare)
Isoflavones and Rotenoids from the Leaves of Millettia oblata ssp teitensis
2017
Ingår i: Journal of Natural Products. - : American Chemical Society (ACS). - 0163-3864 .- 1520-6025. ; 80:7, s. 2060-2066
Tidskriftsartikel (refereegranskat) abstract
A new isoflavone, 8-prenylmilldrone (1), and four new rotenoids, oblarotenoids A-D (2-5), along with nine known compounds (6-14), were isolated from the CH2Cl2/CH3OH (1:1) extract of the leaves of Millettia oblata ssp. teitensis by chromatographic separation. The purified compounds were identified by NMR spectroscopic and mass spectrometric analyses, whereas the absolute configurations of the rotenoids were established on the basis of chiroptical data and in some cases by single-crystal X-ray crystallography. Maximaisoflavone J (11) and oblarotenoid C (4) showed weak activity against the human breast cancer cell line MDA-MB-231 with IC50 values of 33.3 and 93.8 mu M, respectively.
3.
Mabeyo, P. E., et al.
(författare)
Selenium Accumulating Leafy Vegetables Are a Potential Source of Functional Foods
2015
Ingår i: International Journal of Food Science. - : Hindawi Limited. - 2356-7015 .- 2314-5765. ; 2015
Tidskriftsartikel (refereegranskat) abstract
Selenium deficiency in humans has been associated with various diseases, the risks of which can be reduced through dietary supplementation. Selenium accumulating plants may provide a beneficial nutrient for avoiding such illnesses. Thus, leafy vegetables such as Amaranthus hybridus, Amaranthus sp., Cucurbita maxima, Ipomoea batatas, Solanum villosum, Solanum scabrum, and Vigna unguiculata were explored for their capabilities to accumulate selenium when grown on selenium enriched soil and for use as a potential source of selenium enriched functional foods. Their selenium contents were determined by spectrophotometry using the complex of 3,3′-diaminobenzidine hydrochloride (DABH) as a chromogen. The mean concentrations in the leaves were found to range from to μg/g dry weight (DW), with C. maxima accumulating the most selenium. In stems, the accumulated selenium content ranged from μg/g in Amaranthus sp. to μg/g DW in C. maxima and was hence significantly different (). The cancer cell line MDA-MB-231 was used in cytotoxicity assays to determine the anticancer potential of these extracts. With exception of S. scabrum and S. villosum, no cytotoxicity was detected for the selenium enriched vegetable extracts up to 100μg/mL concentration. Hence, following careful evaluation the studied vegetables may be considered as selenium enriched functional foods.
4.
Makungu, Marco, et al.
(författare)
Pterocarpans and isoflavones from the roots of Millettia micans and of Millettia dura
2016
Ingår i: Advances in Drug Discovery and Development. ; 1:1, s. 1-8
Tidskriftsartikel (refereegranskat) abstract
From the CH2Cl2/CH3OH (1:1) extract of the root bark of Millettia micans, a new pterocarpan, (6aR,11aR)-7,8,9-trimethoxy-3-hydroxypterocarpan (1), named micanspterocarpan, was isolated. Similarinvestigation of the CH2Cl2/CH3OH (1:1) extract of the root bark of Millettia dura gave a further new pterocarpan,3-O-prenylmaackiain (2) along with six known isoflavones (3-8) and a chalcone (9). All purifiedcompounds were identified by NMR and MS, and the absolute configuration of 1 was established by quantumchemical CD calculation. The isolated constituents, calopogonium isoflavone B (3) and isoerythrin A-4'-(3-methylbut-2-enyl) ether (4) showed marginal activities against the 3D7 and the Dd2 strains of Plasmodiumfalciparum (70-90% inhibition at 40 M). Maximaisoflavone B (5) and 7,2'-dimethoxy-4',5'-methylenedioxyisoflavone (7) were weakly cytotoxic (IC50 153.5 and 174.1 uM, respectively) against theMDB-MB-231 human breast cancer cell line. None of the tested compounds showed toxicity against theHEK-293 human embryonic kidney cell line at 40 uM.
5.
Nyandoro, Stephen S., 1975, et al.
(författare)
N-Cinnamoyltetraketide Derivatives from the Leaves of Toussaintia orientalis
2015
Ingår i: Journal of natural products. - : American Chemical Society (ACS). - 0163-3864 .- 1520-6025. ; 78:8, s. 2045-2050
Tidskriftsartikel (refereegranskat) abstract
Seven N-cinnamoyltetraketides (1–7), including the new Z-toussaintine E (2), toussaintine F (6), and toussaintine G (7), were isolated from the methanol extract of the leaves of Toussaintia orientalis using column chromatography and HPLC. The configurations of E-toussaintine E (1) and toussaintines A (3) and D (5) are revised based on single-crystal X-ray diffraction data from racemic crystals. Both the crude methanol extract and the isolated constituents exhibit antimycobacterial activities (MIC 83.3–107.7 μM) against the H37Rv strain of Mycobacterium tuberculosis. Compounds 1, 3, 4, and 5 are cytotoxic (ED50 15.3–105.7 μM) against the MDA-MB-231 triple negative aggressive breast cancer cell line.
6.
Nyandoro, Stephen S., 1975, et al.
(författare)
Polyoxygenated Cyclohexenes and Other Constituents of Cleistochlamys kirkii Leaves
2017
Ingår i: Journal of natural products. - : American Chemical Society (ACS). - 0163-3864 .- 1520-6025. ; 80:1, s. 114-125
Tidskriftsartikel (refereegranskat) abstract
Thirteen new metabolites, including the polyoxygenated cyclohexene derivatives cleistodiendiol (1), cleistodienol B (3), cleistenechlorohydrins A (4) and B (5), cleistenediols A–F (6–11), cleistenonal (12), and the butenolide cleistanolate (13), 2,5-dihydroxybenzyl benzoate (cleistophenolide, 14), and eight known compounds (2, 15–21) were isolated from a MeOH extract of the leaves of Cleistochlamys kirkii. The purified metabolites were identified by NMR spectroscopic and mass spectrometric analyses, whereas the absolute configurations of compounds 1, 17, and 19 were established by single-crystal X-ray diffraction. The configuration of the exocyclic double bond of compound 2 was revised based on comparison of its NMR spectroscopic features and optical rotation to those of 1, for which the configuration was determined by X-ray diffraction. Observation of the co-occurrence of cyclohexenoids and heptenolides in C. kirkii is of biogenetic and chemotaxonomic significance. Some of the isolated compounds showed activity against Plasmodium falciparum (3D7, Dd2), with IC50 values of 0.2–40 μM, and against HEK293 mammalian cells (IC50 2.7–3.6 μM). While the crude extract was inactive at 100 μg/mL against the MDA-MB-231 triple-negative breast cancer cell line, some of its isolated constituents demonstrated cytotoxic activity with IC50 values ranging from 0.03–8.2 μM. Compound 1 showed the most potent antiplasmodial (IC50 0.2 μM) and cytotoxic (IC50 0.03 μM, MDA-MB-231 cell line) activities. None of the compounds investigated exhibited translational inhibitory activity in vitro at 20 μM.
7.
Aspholm-Hurtig, Marina, et al.
(författare)
Functional adaptation of BabA, the H. pylori ABO blood group antigen binding adhesin.
2004
Ingår i: Science (New York, N.Y.). - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 305:5683, s. 519-22
Tidskriftsartikel (refereegranskat) abstract
Adherence by Helicobacter pylori increases the risk of gastric disease. Here, we report that more than 95% of strains that bind fucosylated blood group antigen bind A, B, and O antigens (generalists), whereas 60% of adherent South American Amerindian strains bind blood group O antigens best (specialists). This specialization coincides with the unique predominance of blood group O in these Amerindians. Strains differed about 1500-fold in binding affinities, and diversifying selection was evident in babA sequences. We propose that cycles of selection for increased and decreased bacterial adherence contribute to babA diversity and that these cycles have led to gradual replacement of generalist binding by specialist binding in blood group O-dominant human populations.
8.
Dinér, Peter, 1976, et al.
(författare)
Preparation of 3-Substituted-1-Isopropyl-1H-pyrazolo 3,4-d pyrimidin-4-amines as RET Kinase Inhibitors
2012
Ingår i: Journal of Medicinal Chemistry. - : American Chemical Society (ACS). - 0022-2623 .- 1520-4804. ; 55:10, s. 4872-4876
Tidskriftsartikel (refereegranskat) abstract
A series of 3-substituted-1-isopropyl-1H-pyrazolo[3,4-d]pyrimidin-4-amines have been designed, synthesized, and evaluated as RET protein kinase inhibitors. On the basis of docking results, a small library of pyrazolopyrimidine compounds with an extended hydrophobic side arm was synthesized. The most promising of the compounds (7a) displayed efficient inhibition in vitro and good selectivity when tested on a panel of kinases. Furthermore, 7a inhibited GDNF-induced RET phosphorylation of ERK1/2 in MCF-7 breast cancer cells at concentrations as low as 100 nM.
9.
Johansson, Staffan, 1976, et al.
(författare)
Mechanistic Proposal for the Formation of Specific Immunogenic Complexes via a Radical Pathway: A Key Step in Allergic Contact Dermatitis to Olefinic Hydroperoxides
2009
Ingår i: Chem. Res. Toxicol.. - : American Chemical Society (ACS). - 0893-228X .- 1520-5010. ; 22:11, s. 1774-1781
Tidskriftsartikel (refereegranskat) abstract
The widespread use of scented products causes an increase of allergic contact dermatitis to fragrance compounds in Western countries today. Many fragrance compounds are prone to autoxidation, forming hydroperoxides as their primary oxidation products. Hydroperoxides are known to be strong allergens and to form specific immunogenic complexes. However, the mechanisms for the formation of the immunogenic complexes are largely unknown. We have investigated this mechanism for (5R)-5-isopropenyl-2-methyl-2-cyclohexene-1-hydroperoxide (Lim-2-OOH) by studying the formation of adducts in the reaction between this hydroperoxide and 5,10,15,20-tetraphenyl-21H,23H-porphine iron(III) chloride (Fe(III)TPPCl) in the presence of protected cysteine (NAc-Cys-OMe) or glutathione (GSH). Isolated adducts originate from the addition of the thiol group of NAc-Cys-OMe over the carbon−carbon double bonds of carvone. Furthermore, adducts between NAc-Cys-OMe and carveol as well as between GSH and carvone have been identified. The formation of these adducts most likely proceeds via the radical thiol−ene mechanism. The addition of a terpene moiety to cysteine offers an explanation of the specificity of the immune response to structurally different hydroperoxides. These results also explain the lack of cross-reactivity between carvone and Lim-2-OOH. In conclusion, we propose that immunogenic complexes of olefinic hydroperoxides can be formed via the radical thiol−ene mechanism. These complexes will be specific for the individual olefinic hydroperoxides due to the inclusion of a terpene moiety derived from the hydroperoxide.
10.
Karlsson, Isabella, 1980, et al.
(författare)
Photodegradation of Dibenzoylmethanes: Potential Cause of Photocontact Allergy to Sunscreens
2009
Ingår i: Chemical Research in Toxicology. - : American Chemical Society (ACS). - 0893-228X .- 1520-5010. ; 22:11, s. 1881-1892
Tidskriftsartikel (refereegranskat) abstract
One of the most frequently observed photoallergens today is the sunscreen agent 4-tert-butyl-4′-methoxy dibenzoylmethane (1a). The structurally similar compound, 4-isopropyldibenzoylmethane (1b), was a common cause of sunscreen allergy in the eighties and early nineties but was removed from the market in 1993 and replaced with dibenzoylmethane 1a. We have studied the photodegradation of the dibenzoylmethane 1a, to better understand how these substances cause an immune reaction. Several expected degradation products were formed and identified. Of these, arylglyoxals and benzils were of particular interest because they were unexplored as potential contact allergens. The allergenic potential of photodegraded 1a was evaluated by screening the formed arylglyoxals and benzils for their sensitizing capacity in the murine local lymph node assay. The arylglyoxals were found to be strong sensitizers. They were also found to be highly reactive toward the nucleophile arginine, which indicates that the immunogenic hapten-protein complex could be formed via an electrophilic-nucleophilic pathway. By varying the electron-withdrawing or -donating capacity of the substituent in the para position of the arylglyoxal, the electronic effects were shown to have no significant impact on either the sensitizing or the electrophilic power of arylglyoxals. Thus, a change in the substitution pattern of the parent dibenzoylmethane will not influence the sensitizing capacity of the products formed from them upon photodegradation. Furthermore, the combined studies of benzils, using the local lymph node assay and a cell proliferation assay, indicate that the benzils are cytotoxic rather than allergenic. Taken together, this study presents strong indication that photocontact allergy to dibenzoylmethanes is caused by the arylglyoxals that are formed upon photodegradation.
