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Publikationen - Natur- und Wirkstoffchemie

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Publikation

Wrenger, S.; Faust, J.; Mrestani-Klaus, C.; Brandt, W.; Thielitz, A.; Neubert, K.; Reinhold, D.; Non-substrate peptides influencing dipeptidyl peptidase IV/CD26 activity and immune cell function Front. Biosci. Volume, 3194, (2008) DOI: 10.2741/2920

Investigations using inhibitors of dipeptidyl peptidase IV (DP IV) activities and DP IV-/- mice indicated an immunoregulatory role of DP IV that could not be compensated by DP IV-like enzymes. The HIV-1 Tat protein was identified as the first natural inhibitor of DP IV and as immunosuppressor. This review summarizes our investigations on the identification of the amino acid motif of Tat responsible for DP IV inhibition and of endogenous DP IV-inhibitory ligands that suppress immune cell activation. Examinations on numerous peptides carrying the N-terminal Xaa-Xaa-Pro motif of Tat revealed that tryptophan at position two strongly enhanced DP IV inhibition and immunosuppression. Here, we present evidence that the thromboxane A2 receptor exposing N-terminal Met-Trp-Pro at the cell surface could be a potential endogenous, inhibitory DP IV ligand. Moreover, our data suggest that the major envelope proteins p37k of the orhtopoxviruses variola virus and vaccinia virus, as well as the B2L antigen of the parapoxvirus orf, that also carry N-terminal Met-Trp-Pro, could mediate immunosuppressive effects. Further examinations are in progress to identify new physiologic, inhibitory DP IV ligands and to enlighten the mechanism underlying the DP IV-mediated effects.
Publikation

Wessjohann, L.; Schneider, A.; Synthesis of Selenocysteine and Its Derivatives with an Emphasis on Selenenylsulfide (-Se-S-) Formation Chem. Biodivers. 5, 375-388, (2008) DOI: 10.1002/cbdv.200890038

A short survey of historic and current methods for the synthesis of selenocysteine, selenocystine, and derivatives and related compounds is presented, with an additional emphasis on the formation of selenocysteine‐derived SeS bridges. The majority of methods to the amino acid starts with protected and O ‐activated serine, but also other concepts are included such as radical or multicomponent strategies, the latter allowing also direct access to peptoids in one pot. Of special importance is the monomeric oxidative cyclization of selenocysteine–cysteine peptides to eight‐membered and larger rings with a selenenylsulfide bridge, a crucial element in several selenoproteins.
Publikation

Wessjohann, L. A.; Schmidt, G.; Schrekker, H. S.; Reaction of secondary and tertiary aliphatic halides with aromatic aldehydes mediated by chromium(II): a selective cross-coupling of alkyl and ketyl radicals Tetrahedron 64, 2134-2142, (2008) DOI: 10.1016/j.tet.2007.12.039

Takai–Utimoto reactions with secondary and tertiary aliphatic halides usually failed according to previous reports. Now, significant improvements could be achieved, and especially secondary aliphatic halides can be coupled to aromatic aldehydes in yields of up to >95%. A variety of processes are competing with the desired one, and thus conditions must be adapted to the nature of the aldehyde as well as the aliphatic halide used, as the outcome of these reactions is strongly affected by the putative radical intermediates.
Publikation

Wessjohann, L.; Zhu, M.; Amino Alcohols in Organocatalysed Acylation and Deacylation: The Effect of Dialkylamino Substituents on the Rate Adv. Synth. Catal. 350, 107-112, (2008) DOI: 10.1002/adsc.200600491

In alcohols and esters, a neighbouring dialkylamino group can enhance the reactivity towards acylation and deacylation, respectively, that is, such amino alcohols can act as transacylation catalysts like DMAP. This effect is dependent on the number of (carbon) spacer atoms, flexibility of the molecule and the presence and position of further heteroatoms. Based on this effect, the site selective acylation and deacylation of desmycosin, a macrocycle antibiotic possessing an amino sugar moiety, is described.
Publikation

Vercillo, O. E.; Andrade, C. K. Z.; Wessjohann, L. A.; Design and Synthesis of Cyclic RGD Pentapeptoids by Consecutive Ugi Reactions Org. Lett. 10, 205-208, (2008) DOI: 10.1021/ol702521g

A new strategy for the synthesis of cyclic peptoids was developed. The approach is based on the use of consecutive Ugi reactions for the assembly of the acyclic peptoid and for the ring closure. Cyclopentapeptoid analogues of the RGD peptides were designed and synthesized using this methodology. The results confirm the versatility and efficiency of the method for the preparation of cyclic oligopeptoids.
Publikation

Teichert, A.; Lübken, T.; Schmidt, J.; Kuhnt, C.; Huth, M.; Porzel, A.; Wessjohann, L.; Arnold, N.; Determination of β‐carboline alkaloids in fruiting bodies of Hygrophorus spp. by liquid chromatography/electrospray ionisation tandem mass spectrometry Phytochem. Anal. 19, 335-341, (2008) DOI: 10.1002/pca.1057

The β ‐carboline alkaloids harmane (1 ) and norharmane (2 ) were isolated from fruiting bodies of Hygrophorus eburneus (Bull.) Fr. as well as brunnein A (3 ) from Hygrophorus hyacinthinus Quél. (Tricholomataceae, Agaricales) for the first time. Their occurrence within the genus was investigated using liquid chromatography/electrospray ionisation tandem mass spectrometric methods, especially by selected reaction monitoring. Based on these results their chemotaxonomical relevance is discussed.
Publikation

Teichert, A.; Schmidt, J.; Porzel, A.; Arnold, N.; Wessjohann, L.; N-Glucosyl-1H-indole Derivatives from Cortinarius brunneus (Basidiomycetes) Chem. Biodivers. 5, 664-669, (2008) DOI: 10.1002/cbdv.200890062

Two new N ‐glucosylated indole alkaloids were isolated from fruiting bodies of the basidiomycete Cortinarius brunneus (Pers .) Fr . The structures were elucidated by means of the spectroscopic data. Additionally, the very recently reported compounds N‐ 1‐β‐ glucopyranosyl‐3‐(carboxymethyl)‐1H ‐indole (3 ) and N‐ 1‐β‐ glucopyranosyl‐3‐(2‐methoxy‐2‐oxoethyl)‐1H ‐indole (4 ) could be detected. Compound 3 is the N ‐glucoside of the plant‐growth regulator 1H ‐indole‐3‐acetic acid (IAA), but, in contrast, it does not exhibit auxin‐like activity in an Arabidopsis thaliana tap root elongation assay.
Publikation

Teichert, A.; Schmidt, J.; Porzel, A.; Arnold, N.; Wessjohann, L.; (Iso)-Quinoline Alkaloids from Fungal Fruiting Bodies of Cortinarius subtortus J. Nat. Prod. 71, 1092-1094, (2008) DOI: 10.1021/np8000859

Chemical analysis of the fruiting bodies of the agaricoid fungus Cortinarius subtortus yielded three new natural products, two quinoline and one isocarbostyryl alkaloid. The structures of compounds 1−3 were determined by analysis of NMR and MS data. Compound 1 exhibited inhibitory effects against the phytopathogenic fungus Colletotrichum coccodes. All three compounds displayed moderate antioxidant activity in a DPPH free radical scavenging bioassay.
Publikation

Stehle, F.; Brandt, W.; Schmidt, J.; Milkowski, C.; Strack, D.; Activities of Arabidopsis sinapoylglucose:malate sinapoyltransferase shed light on functional diversification of serine carboxypeptidase-like acyltransferases Phytochemistry 69, 1826-1831, (2008) DOI: 10.1016/j.phytochem.2008.03.021

Analysis of the catalytic properties of the serine carboxypeptidase-like (SCPL) 1-O-sinapoyl-β-glucose:l-malate sinapoyltransferase (SMT) from Arabidopsis showed that the enzyme exhibits besides its primary sinapoylation of l-malate, minor hydrolytic and disproportionation activities, producing free sinapic acid and 1,2-di-O-sinapoyl-β-glucose, respectively. The ability of the enzyme to liberate sinapic acid from the donor molecule 1-O-sinapoyl-β-glucose indicates the existence of a short-lived acylenzyme intermediate in the proposed random sequential bi–bi mechanism of catalysis. SMT-catalyzed formation of disinapoylglucose has been corroborated by docking studies with an established homology structure model that illustrates the possible binding of two 1-O-sinapoyl-β-glucose molecules in the active site and the intermolecular reaction of the two glucose esters. The SMT gene is embedded in a tandem cluster of five SCPL sinapoyltransferase genes, which encode enzymes with high amino acid sequence identities and partially overlapping substrate specificities. We assume that in recent duplications of genes encoding SCPL proteins, neofunctionalization of the duplicates to accept 1-O-sinapoyl-β-glucose as acyl donor was gained first, followed by subfunctionalization leading to different acyl acceptor specificities.
Publikation

Schullehner, K.; Dick, R.; Vitzthum, F.; Schwab, W.; Brandt, W.; Frey, M.; Gierl, A.; Benzoxazinoid biosynthesis in dicot plants Phytochemistry 69, 2668-2677, (2008) DOI: 10.1016/j.phytochem.2008.08.023

Benzoxazinoids are common defence compounds of the grasses and are sporadically found in single species of two unrelated orders of the dicots. In the three dicotyledonous species Aphelandra squarrosa, Consolida orientalis and Lamium galeobdolon the main benzoxazinoid aglucon is 2,4-dihydroxy-2H-1,4-benzoxazin-3(4H)-one (DIBOA). While benzoxazinoids in Aphelandra squarrosa are restricted to the root, in Consolida orientalis and Lamium galeobdolon DIBOA is found in all above ground organs of the adult plant in concentrations as high as in the seedling of maize. The initial biosynthetic steps in dicots and monocots seem to be identical. Indole is most probably the first specific intermediate that is oxygenated to indolin-2-one by a cytochrome P450 enzyme. C. orientalis has an active indole-3-glycerolphosphate lyase for indole formation that evolved independently from its orthologous function in maize. The properties and evolution of plant indole-3-glycerolphosphate lyases are discussed.
  • Die Leibniz-Gemeinschaft
  • Digitalisierung in der Landwirtschaft
  • Martin-Luther Universität Halle
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