zur Suche springenzur Navigation springenzum Inhalt springen

Publikationen - Natur- und Wirkstoffchemie

Sortieren nach: Erscheinungsjahr Typ der Publikation

Zeige Ergebnisse 1 bis 10 von 25.

Publikation

Neves Filho, R. A. W.; Westermann, B.; Wessjohann, L. A.; Synthesis of (−)-julocrotine and a diversity oriented Ugi-approach to analogues and probes Beilstein J. Org. Chem. 7, 1504-1507, (2011) DOI: 10.3762/bjoc.7.175

An improved total synthesis of (−)-julocrotine in three steps from Cbz-glutamine, in 51% overall yield, is presented. To demonstrate the potential of the heterocyclic moiety for diversity oriented synthesis, a series of (−)-julocrotine analogues was synthesized by employing the heterocyclic precursor as an amino input in Ugi four-component reactions (Ugi-4CR) [1].
Publikation

Nawaz, S. A.; Ayaz, M.; Brandt, W.; Wessjohann, L. A.; Westermann, B.; Cation–π and π–π stacking interactions allow selective inhibition of butyrylcholinesterase by modified quinine and cinchonidine alkaloids Biochem. Biophys. Res. Commun. 404, 935-940, (2011) DOI: 10.1016/j.bbrc.2010.12.084

Scaffold varied quaternized quinine and cinchonidine alkaloid derivatives were evaluated for their selective butyrylcholinesterase (BChE) inhibitory potential. Ki values were between 0.4–260.5 μM (non-competitive inhibition) while corresponding Kivalues to acetylcholinesterase (AChE) ranged from 7.0–400 μM exhibiting a 250-fold selectivity for BChE.Docking arrangements (GOLD, PLANT) revealed that the extended aromatic moieties and the quaternized nitrogen of the inhibitors were responsible for specific π–π stacking and π–cation interactions with the choline binding site and the peripheral anionic site of BChE’s active site.
Publikation

Mansfeld, J.; Brandt, W.; Haftendorn, R.; Schöps, R.; Ulbrich-Hofmann, R.; Discrimination between the regioisomeric 1,2- and 1,3-diacylglycerophosphocholines by phospholipases Chem. Phys. Lipids 164, 196-204, (2011) DOI: 10.1016/j.chemphyslip.2010.12.009

The artificial 1,3-diacyl-glycero-2-phosphocholines (1,3-PCs), which form similar aggregate structures as the naturally occurring 1,2-diacyl-sn-glycero-3-phosphocholines (1,2-PCs), were tested as substrates for different classes of phospholipases such as phospholipase A2 (PLA2) from porcine pancreas, bee and snake venom, and Arabidopsis thaliana, phospholipase C (PLC) from Bacillus cereus, and phospholipase D (PLD) from cabbage and Streptomyces species. The regioisomers of the natural phospholipids were shown to bind to all investigated phospholipases with an affinity similar to the corresponding naturally occurring phospholipids, however their hydrolysis was reduced to different degrees (PLA2s and PLC) or even abolished (PLDs belonging to the PLD superfamily). The results are in accordance with binding models obtained by docking the substrates to the crystal structures or homology models of the phospholipases.
Publikation

Lee, D.-U.; Park, J. H.; Wessjohann, L.; Schmidt, J.; Alkaloids from Papaver coreanum Nat. Prod. Commun. 6, 1593-1594, (2011) DOI: 10.1177/1934578X1100601109

The alkaloid pattern of the endemic plant Papaver coreanum Nakai (Papaveraceae) was determined for the first time. Eight alkaloids could be identified by LC/ESIMS/MS and high-resolution mass spectrometry. Among them, protopine and allocryptopine represent the main components. Besides norsanguinarine, sanguinarine, dihydrosanguinarine, oxysanguinarine, lincangenine, and cryptopine, some other trace alkaloids were found whose structures remain unknown.
Publikation

Kopycki, J.; Schmidt, J.; Abel, S.; Grubb, C. D.; Chemoenzymatic synthesis of diverse thiohydroximates from glucosinolate-utilizing enzymes from Helix pomatia and Caldicellulosiruptor saccharolyticus Biotechnol. Lett. 33, 1039-1046, (2011) DOI: 10.1007/s10529-011-0530-y

Thiohydroximates comprise a diverse class of compounds important in both biological and industrial chemistry. Their syntheses are generally limited to simple alkyl and aryl compounds with few stereocenters and a narrow range of functional groups. We hypothesized that sequential action of two recombinant enzymes, a sulfatase from Helix pomatia and a β-O-glucosidase from Caldicellulosiruptor saccharolyticus, on glucosinolates would allow synthesis of thiohydroximates from a structurally broad array of abundant precursors. We report successful synthesis of thiohydroximates of varied chemical classes, including from homochiral compounds of demonstrated biological activity. The chemoenzymatic synthetic route reported here should allow access to many, if not all, of the thiohydroximate core structures of the ~200 known naturally occurring glucosinolates. The enrichment of this group for compounds with possible pharmacological potential is discussed.
Publikation

Heinke, R.; Franke, K.; Porzel, A.; Wessjohann, L. A.; Awadh Ali, N. A.; Schmidt, J.; Furanocoumarins from Dorstenia foetida Phytochemistry 72, 929-934, (2011) DOI: 10.1016/j.phytochem.2011.03.008

The linear furanocoumarins 5-(2,3-epoxy-3-methyl-butoxy)-chalepensin, 5-methoxy-3-(3-methyl-2,3-dihydroxybutyl)-psoralen-diacetate (7), 5-methoxy-3-[3-(β-d-glucopyranosyloxy)-2-acetyloxy-3-methyl-butyl]-psoralen and 5-(3-methyl-2,3-dihydroxybutyloxy)-3-[3-(β-d-glucopyranosyloxy)-2-hydroxy-3-methyl-butyl]-psoralen, and the coumarin derivative 7-hydroxy-5-methoxy-6-carboxymethyl-3-[3-(β-d-glucopyranosyloxy)-2-hydroxy-3-methyl-butyl]-coumarin were isolated from the leaves of Dorstenia foetida (Moraceae) along with the known compounds psoralen, bergapten, isopimpinellin, phellopterin, 5-methoxychalepensin and turbinatocoumarin. Further furanocoumarins were characterized by ESI-MS/MS investigations. The nonpolar extracts of D. foetida exhibit antifungal, antibacterial and cytotoxic activity, however, no anthelminthic activity.
Publikation

Geissler, T.; Wessjohann, L. A.; A Whole-Plant Microtiter Plate Assay for Drought Stress Tolerance-Inducing Effects J. Plant Growth Regul. 30, 504-511, (2011) DOI: 10.1007/s00344-011-9212-1

The frequency and intensity of extreme weather events and global temperature are rising, which poses a potential threat to life, specifically crops, and therefore food and bioenergy supply. Reduced water availability has the most severe impact on potential grain yield. Negative effects of transient drought stress (dry spells) can be countered by drought tolerance-inducing chemicals. In search for useful compounds, biochemical assays are fast but limited in scope, whereas whole-plant assays are slow, require large amounts of compounds, and are usually not concentration-related. Here we report the development of a fast, concentration-dependent whole-plant assay using the fast growing duckweed Lemna minor L. 4-Amino-1,8-naphthalimide (1) and the imidacloprid metabolite 6-chloronicotinic acid (2) were affirmed as drought stress tolerance enhancers. Both also reduce oxidative stress-induced cell death in Arabidopsis thaliana (L.) Heynh. cell suspension culture but show differences in their mode of action.
Publikation

Fredericks, W. J.; McGarvey, T.; Wang, H.; Lal, P.; Puthiyaveettil, R.; Tomaszewski, J.; Sepulveda, J.; Labelle, E.; Weiss, J. S.; Nickerson, M. L.; Kruth, H. S.; Brandt, W.; Wessjohann, L. A.; Malkowicz, S. B.; The Bladder Tumor Suppressor Protein TERE1 (UBIAD1) Modulates Cell Cholesterol: Implications for Tumor Progression DNA Cell Biol. 30, 851-864, (2011) DOI: 10.1089/dna.2011.1315

Convergent evidence implicates the TERE1 protein in human bladder tumor progression and lipid metabolism. Previously, reduced TERE1 expression was found in invasive urologic cancers and inhibited cell growth upon re-expression. A role in lipid metabolism was suggested by TERE1 binding to APOE, a cholesterol carrier, and to TBL2, a candidate protein in triglyceride disorders. Natural TERE1 mutations associate with Schnyder's corneal dystrophy, characterized by lipid accumulation. TERE1 catalyzes menaquinone synthesis, known to affect cholesterol homeostasis. To explore this relationship, we altered TERE1 and TBL2 dosage via ectopic expression and interfering RNA and measured cholesterol by Amplex red. Protein interactions of wild-type and mutant TERE1 with GST-APOE were evaluated by binding assays and molecular modeling. We conducted a bladder tumor microarray TERE1 expression analysis and assayed tumorigenicity of J82 cells ectopically expressing TERE1. TERE1 expression was reduced in a third of invasive specimens. Ectopic TERE1 expression in J82 bladder cancer cells dramatically inhibited nude mouse tumorigenesis. TERE1 and TBL2 proteins inversely modulated cellular cholesterol in HEK293 and bladder cancer cells from 20% to 50%. TERE1 point mutations affected APOE interactions, and resulted in cholesterol levels that differed from wild type. Elevated tumor cell cholesterol is known to affect apoptosis and growth signaling; thus, loss of TERE1 in invasive bladder cancer may represent a defect in menaquinone-mediated cholesterol homeostasis that contributes to progression.
Publikation

Dubberke, S.; Abbas, M.; Westermann, B.; Oxidative allylic rearrangement of cycloalkenols: Formal total synthesis of enantiomerically pure trisporic acid B Beilstein J. Org. Chem. 7, 421-425, (2011) DOI: 10.3762/bjoc.7.54

Enantiomerically highly enriched unsaturated β-ketoesters bearing a quaternary stereocenter can be utilized as building blocks for the synthesis of natural occurring terpenes, i. a., trisporic acid and its derivatives. An advanced building block has been synthesized in a short reaction sequence, which involves an oxidative allylic rearrangement initiated by pyridinium dichromate (PDC) as the key step.
Publikation

Dąbrowska, P.; Shabab, M.; Brandt, W.; Vogel, H.; Boland, W.; Isomerization of the Phytohormone Precursor 12-Oxophytodienoic Acid (OPDA) in the Insect Gut J. Biol. Chem. 286, 22348-22354, (2011) DOI: 10.1074/jbc.M111.244509

12-Oxophytodienoic acid (OPDA) is isomerized in the gut of herbivorous insects to tetrahydrodicranenone B (iso-OPDA). The transformation is achieved by a glutathione S-transferase present in the gut epithelium. Experiments with 9-[2H]-iso-OPDA demonstrated the complete retention of the deuterium atom in the product 11-[2H]-OPDA consistent with an intramolecular 1,3-hydrogen shift. Homology modeling based on the x-ray structure of a glutathione S-transferase from Anopheles gambiae revealed that the co-factor glutathione does not covalently bind to the substrate but appears to be involved in the initial deprotonation and enolization of the OPDA. The transformation resembles that of a mammalian GST-catalyzed isomerization of Δ5-3-ketosteroids to Δ4-3-ketosteroids or the conversion of prostaglandin A1 to the biologically inactive prostaglandin B1.
  • Die Leibniz-Gemeinschaft
  • Digitalisierung in der Landwirtschaft
  • Martin-Luther Universität Halle
IPB Mainnav Search