TY - JOUR ID - 1529 TI - Secondary metabolites from Helichrysum foetidum and their chemotaxonomic significance JO - Biochem. Syst. Ecol. PY - 2011 SP - 166-167 AU - Zanetsie Kakam, A. M. AU - Franke, K. AU - Ndom, J. C. AU - Dongo, E. AU - Mpondo, T. N. AU - Wessjohann, L. A. AU - VL - 39 UR - DO - 10.1016/j.bse.2011.02.005 AB - The occurrence of tetracyclic kauran type diterpenoids or related structures might be a valuable chemotaxonomic marker for further classification and subdivision of the polyphyletic genus Helichrysum. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 1528 TI - Compositional and Structural Studies of the Major and Minor Components in Three Cameroonian Seed Oils by GC–MS, ESI-FTICR-MS and HPLC JO - J. Am. Oil. Chem. Soc. PY - 2011 SP - 1539-1549 AU - Yeboah, S. O. AU - Mitei, Y. C. AU - Ngila, J. C. AU - Wessjohann, L. AU - Schmidt, J. AU - VL - 88 UR - DO - 10.1007/s11746-011-1832-x AB - The lipid components of three Cameroonian seed oils, ke tchock (Aframomum arundinaceum), njangsa (Ricinodendron heudelotii) and calabash nutmeg (Monodora myristica), have been investigated. Gas chromatography (GC)–mass spectrometry (MS) fatty acid (FA) analysis showed M. myristica seed oil to be dominated by linoleic (49.29%) and oleic (37.17%) acids; R. heudelotii was mainly linoleic (58.73%), followed by stearic (15.00%) and oleic (14.21%) acids; A. arundinaceum was predominantly oleic (65.76%) and palmitic (20.36%) acids. Electrospray ionization (ESI)-Fourier transform ion cyclotron resonance (FTICR)-MS analysis showed seven major triacylglycerol (TAG) classes for M. myristica, with C54:5, C54:4 and C54:6 dominating. R. heudelotii had eight major TAG classes with C54:8, C54:7 and C54:6 being most abundant. A. arundinaceum also had eight major TAG classes with C52:2, C54:3 and C50:2 dominating. 13C nuclear magnetic resonance (NMR) analysis of the TAGs showed that both sn-1,3 and sn-2 positions were predominantly occupied by linoleoyl and oleoyl chains. High-performance liquid chromatography (HPLC) fluorescence detector (FLD) analysis showed that M. myristica contained only α- and β-tocopherols (195.40 and 73.95 µg/g, respectively), R. heudelotii contained mainly γ-tocopherol (289.40 µg/g), and A. arundinaceum had mainly γ- and β-tocopherols (236.78 and 124.93 µg/g, respectively). GC–MS analysis of the unsaponifiable matter showed that β-sitosterol was the most abundant phytosterol in all three seed oils. The absolute amounts of 4-desmethylsterols were 196.15, 608.71 and 362.15 µg/g for M. myristica, R. heudelotii and A. arundinaceum seed oils, respectively. These compositional and structural studies provide justification for the use of all three seed oils in food products. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 1525 TI - PdII/IV catalyzed oxidative cyclization of 1,6-enynes derived by Ugi-4-component reaction JO - Tetrahedron Lett. PY - 2011 SP - 6295-6297 AU - Welsch, S. J. AU - Umkehrer, M. AU - Ross, G. AU - Kolb, J. AU - Burdack, C. AU - Wessjohann, L. A. AU - VL - 52 UR - DO - 10.1016/j.tetlet.2011.09.094 AB - A variety of 1,6-enynes were synthesized by an Ugi-reaction and further elaborated by a PdII/IV catalyzed oxidative cyclization to produce N-substituted 3-aza-bicyclo[3.1.0]hexan-2-ones. Different substitution patterns were tested to examine the scope and limitations of the amide tethered substrates. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 1519 TI - Isolation of a New Natural Product and Cytotoxic and Antimicrobial Activities of Extracts from Fungi of Indonesian Marine Habitats JO - Mar. Drugs PY - 2011 SP - 294-306 AU - Tarman, K. AU - Lindequist, U. AU - Wende, K. AU - Porzel, A. AU - Arnold, N. AU - Wessjohann, L. A. AU - VL - 9 UR - DO - 10.3390/md9030294 AB - In the search for bioactive compounds, 11 fungal strains were isolated from Indonesian marine habitats. Ethyl acetate extracts of their culture broth were tested for cytotoxic activity against a urinary bladder carcinoma cell line and for antifungal and antibacterial activities against fish and human pathogenic bacteria as well as against plant and human pathogenic fungi. The crude extract of a sterile algicolous fungus (KT31), isolated from the red seaweed Kappaphycus alvarezii (Doty) Doty ex P.C. Silva exhibited potent cytotoxic activity with an IC50 value of 1.5 µg/mL. Another fungal strain (KT29) displayed fungicidal properties against the plant pathogenic fungus Cladosporium cucumerinum Ell. et Arth. at 50 µg/spot. 2-Carboxy-8-methoxy-naphthalene-1-ol (1) could be isolated as a new natural product. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 1517 TI - Interactions of polysulfanes with components of red blood cells JO - Med. Chem. Commun. PY - 2011 SP - 196-200 AU - Schneider, T. AU - Ba, L. A. AU - Khairan, K. AU - Zwergel, C. AU - Bach, N. D. AU - Bernhardt, I. AU - Brandt, W. AU - Wessjohann, L. AU - Diederich, M. AU - Jacob, C. AU - VL - 2 UR - DO - 10.1039/C0MD00203H AB - Traditionally, the activity of most polysulfanes has been associated with the redox behaviour of the sulfur-sulfur bond. Here we show that polysulfanes, such as diallyltri- and tetrasulfide, also interact with cellular membranes and certain metalloproteins. Together, multiple interactions with various biological targets may explain best the biological activity of such compounds. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 1513 TI - Antibacterial and antioxidant activities and acute toxicity of Bumelia sartorum Mart., Sapotaceae, a Brazilian medicinal plant JO - Rev. Bras. Farmacogn. PY - 2011 SP - 86-91 AU - Ruela, H. S. AU - Leal, I. C. R. AU - de Almeida, M. R. A. AU - dos Santos, K. R. N. AU - Wessjohann, L. A. AU - Kuster, R. M. AU - VL - 21 UR - DO - 10.1590/S0102-695X2011005000035 AB - In order to validate the Bumelia sartorum Mart., Sapotaceae, traditional use for infection diseases, this study evaluates the antibacterial activity of the stem bark fractions against methicillin-sensitive (MSSA) and methicillin-resistant (MRSA) Staphylococcus aureus strains by using the agar dilution method and reported as MIC (minimal inhibitory concentration). In addition, the DPPH scavenging activity of these fractions was measured and the chemical composition and acute toxicity of the active fraction were also determined. The ethyl acetate (EtOAc) extract was chemically analyzed by LC/MS, direct ionization APCI/MS, 1H NMR and 13C-NMR. All fractions, except butanol extract, presented high antioxidant activity, especially the methanol and the EtOAc extracts, which showed EC50 values (5.67 and 5.30 µg/mL, respectively) considerably lower than the Gingko-standard EGb 761® (38.58 µg/mL). The antibacterial activity against S. aureus strains was observed in EtOAc (MIC 256-512 µg/mL), which showed a very low toxicity. The chemical study of this fraction revealed the abundant presence of polyphenolic compounds. The antibacterial and antioxidant activities reported in this paper for EtOAc extract from B. sartorum and the low toxicity of this fraction opens the possibility that it could be helpful for the developing of new antibacterial agents for treating S. aureus infections. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 1512 TI - Topical anti-inflammatory activity of quillaic acid from Quillaja saponaria Mol. and some derivatives JO - J. Pharm. Pharmacol. PY - 2011 SP - 718-724 AU - Rodríguez-Díaz, M. AU - Delporte, C. AU - Cartagena, C. AU - Cassels, B. K. AU - González, P. AU - Silva, X. AU - León, F. AU - Wessjohann, L. A. AU - VL - 63 UR - DO - 10.1111/j.2042-7158.2011.01263.x AB - Objectives Quillaic acid is the major aglycone of the widely studied saponins of the Chilean indigenous tree Quillaja saponaria Mol. The industrial availability of quillaja saponins and the extensive functionalisation of this triterpenoid provide unique opportunities for structural modification and pose a challenge from the standpoint of selectivity in regard to one or the other secondary alcohol group, the aldehyde, and the carboxylic acid functions. The anti‐inflammatory activity of this sapogenin has not been studied previously and it has never been used to obtain potential anti‐inflammatory derivatives.Methods A series of quillaic acid derivatives were prepared and subjected to topical assays for the inhibition of inflammation induced by arachidonic acid or phorbol ester.Key findings Quillaic acid exhibited strong topical anti‐inflammatory activity in both models. Most of its derivatives were less potent, but the hydrazone 8 showed similar potency to quillaic acid in the TPA assay.Conclusions The structural modifications performed and the biological results suggest that the aldehyde and carboxyl groups are relevant to the anti‐inflammatory activity in these models. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 1511 TI - Characterization of the anticancer properties of monoglycosidic cardenolides isolated from Nerium oleander and Streptocaulon tomentosum JO - J. Ethnopharmacol. PY - 2011 SP - 781-788 AU - Rashan, L. J. AU - Franke, K. AU - Khine, M. M. AU - Kelter, G. AU - Fiebig, H. H. AU - Neumann, J. AU - Wessjohann, L. A. AU - VL - 134 UR - DO - 10.1016/j.jep.2011.01.038 AB - Aim of the studyFor identification of the active constituents we investigated the anticancer activity of cardenolides from Streptocaulon tomentosum Wight & Arn. (Asclepiadaceae) and from Nerium oleander L. (Apocynaceae) which are both used against cancer in the traditional medicine in their region of origin.Material, methods and resultsThe antiproliferative activity of cardenolides isolated from roots of Streptocaulon tomentosum (IC50 < 1–15.3 μM after 2 days in MCF7) and of cardenolide containing fractions from the cold aqueous extract of Nerium oleander leaves (“Breastin”, mean IC50 0.85 μg/ml in a panel of 36 human tumor cell lines), their influence on the cellular viability and on the cell cycle (block at the G2/M-phase or at the S-phase in tumor cells, respectively) were determined using different cell lines. The murine cell line L929 and normal non-tumor cells were not affected. Bioactivity guided fractionation of Breastin resulted in the isolation of the monoglycosidic cardenolides oleandrine, oleandrigeninsarmentoside, neritaloside, odoroside H, and odoroside A (IC50-values between 0.010 and 0.071 μg/ml).ConclusionsThe observed anticancer activities of extracts and isolated cardenolides are in agreement with the ethnomedicinal use of Streptocaulon tomentosum and Nerium oleander. The most active anticancer compounds from both species are monoglycosidic cardenolides possessing the 3β,14β-dihydroxy-5β-card-20(22)-enolide structure with or without an acetoxy group at C-16. The results indicate that the cytotoxic effects are induced by the inhibition of the plasma membrane bound Na+/K+-ATPase. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 1508 TI - The Multiple Multicomponent Approach to Natural Product Mimics: Tubugis, N-Substituted Anticancer Peptides with Picomolar Activity JO - J. Am. Chem. Soc. PY - 2011 SP - 7692-7695 AU - Pando, O. AU - Stark, S. AU - Denkert, A. AU - Porzel, A. AU - Preusentanz, R. AU - Wessjohann, L. A. AU - VL - 133 UR - DO - 10.1021/ja2022027 AB - The synthesis of a new generation of highly cytotoxic tubulysin analogues (i.e., tubugis) is described. In the key step, the rare, unstable, and synthetically difficult to introduce tertiary amide–N,O-acetal moiety required for high potency in natural tubulysins is replaced by a dipeptoid element formed in an Ugi four-component reaction. Two of the four components required are themselves produced by other multicomponent reactions (MCRs). Thus, the tubugis represent the first examples of the synthesis of natural-product-inspired compounds using three intertwined isonitrile MCRs. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 1507 TI - Synthesis of (−)-julocrotine and a diversity oriented Ugi-approach to analogues and probes JO - Beilstein J. Org. Chem. PY - 2011 SP - 1504-1507 AU - Neves Filho, R. A. W. AU - Westermann, B. AU - Wessjohann, L. A. AU - VL - 7 UR - DO - 10.3762/bjoc.7.175 AB - 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]. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 1506 TI - Cation–π and π–π stacking interactions allow selective inhibition of butyrylcholinesterase by modified quinine and cinchonidine alkaloids JO - Biochem. Biophys. Res. Commun. PY - 2011 SP - 935-940 AU - Nawaz, S. A. AU - Ayaz, M. AU - Brandt, W. AU - Wessjohann, L. A. AU - Westermann, B. AU - VL - 404 UR - DO - 10.1016/j.bbrc.2010.12.084 AB - 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. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 1502 TI - Discrimination between the regioisomeric 1,2- and 1,3-diacylglycerophosphocholines by phospholipases JO - Chem. Phys. Lipids PY - 2011 SP - 196-204 AU - Mansfeld, J. AU - Brandt, W. AU - Haftendorn, R. AU - Schöps, R. AU - Ulbrich-Hofmann, R. AU - VL - 164 UR - DO - 10.1016/j.chemphyslip.2010.12.009 AB - 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. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 1501 TI - Alkaloids from Papaver coreanum JO - Nat. Prod. Commun. PY - 2011 SP - 1593-1594 AU - Lee, D.-U. AU - Park, J. H. AU - Wessjohann, L. AU - Schmidt, J. AU - VL - 6 UR - DO - 10.1177/1934578X1100601109 AB - 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. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 1500 TI - Chemoenzymatic synthesis of diverse thiohydroximates from glucosinolate-utilizing enzymes from Helix pomatia and Caldicellulosiruptor saccharolyticus JO - Biotechnol. Lett. PY - 2011 SP - 1039-1046 AU - Kopycki, J. AU - Schmidt, J. AU - Abel, S. AU - Grubb, C. D. AU - VL - 33 UR - DO - 10.1007/s10529-011-0530-y AB - 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. A2 - C1 - Molecular Signal Processing; Bioorganic Chemistry ER - TY - JOUR ID - 1492 TI - Furanocoumarins from Dorstenia foetida JO - Phytochemistry PY - 2011 SP - 929-934 AU - Heinke, R. AU - Franke, K. AU - Porzel, A. AU - Wessjohann, L. A. AU - Awadh Ali, N. A. AU - Schmidt, J. AU - VL - 72 UR - DO - 10.1016/j.phytochem.2011.03.008 AB - 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. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 1487 TI - A Whole-Plant Microtiter Plate Assay for Drought Stress Tolerance-Inducing Effects JO - J. Plant Growth Regul. PY - 2011 SP - 504-511 AU - Geissler, T. AU - Wessjohann, L. A. AU - VL - 30 UR - DO - 10.1007/s00344-011-9212-1 AB - 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. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 1486 TI - The Bladder Tumor Suppressor Protein TERE1 (UBIAD1) Modulates Cell Cholesterol: Implications for Tumor Progression JO - DNA Cell Biol. PY - 2011 SP - 851-864 AU - Fredericks, W. J. AU - McGarvey, T. AU - Wang, H. AU - Lal, P. AU - Puthiyaveettil, R. AU - Tomaszewski, J. AU - Sepulveda, J. AU - Labelle, E. AU - Weiss, J. S. AU - Nickerson, M. L. AU - Kruth, H. S. AU - Brandt, W. AU - Wessjohann, L. A. AU - Malkowicz, S. B. AU - VL - 30 UR - DO - 10.1089/dna.2011.1315 AB - 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. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 1483 TI - Oxidative allylic rearrangement of cycloalkenols: Formal total synthesis of enantiomerically pure trisporic acid B JO - Beilstein J. Org. Chem. PY - 2011 SP - 421-425 AU - Dubberke, S. AU - Abbas, M. AU - Westermann, B. AU - VL - 7 UR - DO - 10.3762/bjoc.7.54 AB - 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. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 1480 TI - Isomerization of the Phytohormone Precursor 12-Oxophytodienoic Acid (OPDA) in the Insect Gut JO - J. Biol. Chem. PY - 2011 SP - 22348-22354 AU - Dąbrowska, P. AU - Shabab, M. AU - Brandt, W. AU - Vogel, H. AU - Boland, W. AU - VL - 286 UR - DO - 10.1074/jbc.M111.244509 AB - 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. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 1476 TI - Systematic conformational investigations of peptoids and peptoid-peptide chimeras JO - Biopolymers PY - 2011 SP - 651-668 AU - Brandt, W. AU - Herberg, T. AU - Wessjohann, L. AU - VL - 96 UR - DO - 10.1002/bip.21620 AB - Peptoids are originally defined as N‐substituted oligoglycine derivatives, and in a broader definition as N‐substituted peptides (peptoid–peptide chimeras). Both types were systematically investigated by force field calculations. The Merck MMFF and YASARA2 force fields were shown to be, among others, the most suitable ones for conformational investigations of peptoids with no missing parameterizations, in contrast to AMBER or CHARMM. Ramachandran‐like plots were calculated for dipeptoids and chimeras using energy calculations and grid searches by varying the dihedral angels Φ and Ψ in steps of 10° for s‐cis‐ and s‐trans amide bonds. Barriers as well as low energy conformations are compared to peptide Ramachandran plots, showing that peptoids have both, more barriers due to additional steric interactions as well as access to minimum conformations not accessible by peptides. Low energy conformations of dimers were used as starting conformations of higher oligomers of the peptoids for extensive molecular dynamics simulations over 10 or 20 ns with the YASARA2 force field and an explicit water solvent box to evaluate their potential to form secondary structural elements. Especially peptoids with aminoisobutyric acid‐like monomer units were found to form left‐handed or polyproline‐like helices also known from less common natural peptides. Furthermore, new secondary structures appear feasible based on stable conformations outside the allowed areas of the Ramachandran plot for peptides, but allowed for peptoids. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 1475 TI - Rhodium(I) complexes with κP coordinated ω-phosphinofunctionalized alkyl phenyl sulfide, sulfoxide and sulfone ligands and their reactions with sodium bis(trimethylsilyl)amide and Ag[BF4] JO - J. Organomet. Chem. PY - 2011 SP - 1768-1781 AU - Block, M. AU - Bette, M. AU - Wagner, C. AU - Schmidt, J. AU - Steinborn, D. AU - VL - 696 UR - DO - 10.1016/j.jorganchem.2010.12.019 AB - Reactions of ω-diphenylphosphinofunctionalized alkyl phenyl sulfides Ph2P(CH2)nSPh (n = 1, 1a; 2, 2a; 3, 3a), sulfoxides Ph2P(CH2)nS(O)Ph (n = 1, 1b; 2, 2b; 3, 3b) and sulfones Ph2P(CH2)nS(O)2Ph (n = 1, 1c; 2, 2c; 3, 3c) with dinuclear chlorido bridged rhodium(I) complexes [(RhL2)2(μ-Cl)2] (L2 = cycloocta-1.5-diene, cod, 4; bis(diphenylphosphino)ethane, dppe, 5) afforded mononuclear Rh(I) complexes of the type [RhCl{Ph2P(CH2)nS(O)xPh-κP}(cod)]1 (n/x = 1/0, 6a; 1/1, 6b; 1/2, 6c; 2/0, 8a; 2/1, 8b; 2/2, 8c; 3/0, 10a; 3/1, 10b; 3/2, 10c) and [RhCl{Ph2P(CH2)nS(O)xPh-κP}(dppe)] (n/x = 1/0, 7a; 1/1, 7b; 1/2, 7c; 2/0, 9a; 2/1, 9b; 2/2, 9c; 3/0, 11a; 3/1, 11b; 3/2, 11c) having the P^S(O)x ligands κP coordinated. Addition of Ag[BF4] to complexes 6–11 in CH2Cl2 led with precipitation of AgCl to cationic rhodium complexes of the type [Rh{Ph2P(CH2)nS(O)xPh-κP,κS/O}L2][BF4] having bound the P^S(O)x ligands bidentately in a κP,κS (13a–18a, 15b–18b) or a κP,κO (13b, 14b, 13c–18c) coordination mode. Unexpectedly, the addition of Ag[BF4] to 6a in THF afforded the trinuclear cationic rhodium(I) complex [Rh3(μ-Cl)(μ-Ph2PCH2SPh-κP:κS)4][BF4]2·4THF (12·4THF) with a four-membered Rh3Cl ring as basic framework. Addition of sodium bis(trimethylsilyl)amide to complexes 6–11 led to a selective deprotonation of the carbon atom neighbored to the S(O)x group (α-C) yielding three different types of organorhodium complexes: a) Organorhodium intramolecular coordination compounds of the type [Rh{CH{S(O)xPh}CH2CH2PPh2-κC,κP}L2] (22a–c, 23a–c), b) zwitterionic complexes [Rh{Ph2PCHS(O)xPh-κP,κS/O}L2] having κP,κS (21a, 21b) and κP,κO (20b/c, 21c) coordinated anionic [Ph2PCHS(O)xPh] ligands, and c) the dinuclear rhodium(I) complex [{Rh{μ-CH(SPh)PPh2-κC:κP}(cod)}2] (19). All complexes were fully characterized spectroscopically and complexes 15b, 15c, 12·4THF and 19·THF additionally by X-ray diffraction analysis. DFT calculations of zwitterionic complexes gave insight into the coordination mode of the [Ph2PCHS(O)Ph] ligand (κP,κS versus κP,κO). A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 1473 TI - Fast and efficient microwave-assisted synthesis of functionalized peptoids via Ugi reactions JO - Org. Biomol. Chem. PY - 2011 SP - 5024-5027 AU - Barreto, A. d. F. S. AU - Vercillo, O. E. AU - Birkett, M. A. AU - Caulfield, J. C. AU - Wessjohann, L. A. AU - Andrade, C. K. Z. AU - VL - 9 UR - DO - 10.1039/C1OB05471F AB - A wide range of N-alkylglycines (peptoids) can be efficiently prepared viaUgi reactions using microwave irradiations. The results confirm the versatility and efficiency of the methodology for the preparation of functionalized peptoids. The products can be used in consecutive Ugi reactions to yield cyclic peptoids of potential biological interest. A2 - C1 - Bioorganic Chemistry ER - TY - JOUR ID - 1471 TI - Anticholinesterase activity of endemic plant extracts from Soqotra JO - Afr. J. Tradit. Complement. Altern. Med. PY - 2011 SP - 296-299 AU - Bakthir, H. AU - Awadh Ali, N. A. AU - Arnold, N. AU - Teichert, A. AU - Wessjohann, L. AU - VL - 8 UR - DO - 10.4314/ajtcam.v8i3.65292 AB - A total of 30 chloroform and methanol extracts from the following endemic Soqotran plants Acridocarpus socotranus Olive, Boswellia socotranao Balf.fil, Boswellia elongata Balf. fil., Caralluma socotrana N. Br, Cephalocroton socotranus Balf.f, Croton socotranus Balf. fil.., Dendrosicycos socotrana Balf.f., Dorstenia gigas Schweinf. ex Balf. fil., Eureiandra balfourii Cogn. & Balf. fil., Kalanchoe farinaceae Balf.f, Limonium sokotranum (Vierh) Radcl. Sm), Oldenlandia pulvinata, Pulicaria diversifolia( Balf. and Pulicaria stephanocarpa Balf. were screened for their acetylcholinesterase inhibitory activity by using in vitro Ellman method at 50 and 200 μg/ml concentrations. Chloroform extracts of Croton socotranus, Boswellia socotrana, Dorstenia gigas, and Pulicaria stephanocarpa as well as methanol extracts of Eureiandra balfourii exhibited inhibitory activities higher than 50 % at concentration of 200 μg. At a concentrations of 50 μg, the chloroform extract of Croton socotranus exhibited an inhibition of 40.6 %. A2 - C1 - Bioorganic Chemistry ER - TY - CHAP ID - 99 TI - Multi-Component Reactions in Supramolecular Chemistry and Material Science T2 - MCR 2009 PB - Adv. Exp. Med. Biol. PY - 2011 SP - 173-201 AU - Wessjohann, L. A. AU - Ostrowski, S. AU - Bakulev, V. AU - Berseneva, V. AU - Bogdanov, A. V. AU - Romanova, I. P. AU - Mironov, V. F. AU - Larionova, O. A. AU - Shaikhutdinova, G. R. AU - Sinyashin, O. G. AU - Baibulatova, N. Z. AU - Dokichev, V. A. AU - Fedorova, O. V. AU - Ovchinnikova, I. G. AU - Rusinov, G. L. AU - Titova, J. A. AU - Nasonova, A. AU - Kim, D.-J. AU - Kim, K.-S. AU - Jang, Y. M. AU - Kim, S. J. AU - Rakhimova, E. B. AU - Minnebaev, A. B. AU - Akhmetova, V. R. AU - Qin, C. AU - Zhang, R. AU - Wang, Q. AU - Ren, J. AU - Tian, L. AU - Mironov, M. A. AU - Demina, T. S. AU - Tcoy, A. M. AU - Akopova, T. A. AU - Markvicheva, E. A. AU - Chernyshenko, A. O. AU - Zelenetski, A. N. AU - Pandit, S. S. AU - VL - 699 UR - SN - 978-1-4419-7270-5 DO - 10.1007/978-1-4419-7270-5_6 AB - Multi-component reactions of building blocks with more than one MCR-reactive group will give rise to oligomeric MCR products. The proper choice of at least two bifunctional building blocks will give either a polymeric or a cyclic product. Apart from polymerization, repetitive or consecutive Ugi reactions have been used to produce linear MCR-heterooligomers with such building blocks. A2 - Mironov, M. A., ed. C1 - Bioorganic Chemistry ER - TY - CHAP ID - 98 TI - Chalcogen-Based Organocatalysis T2 - Enantioselective Organocatalyzed Reactions I PB - PY - 2011 SP - 209-314 AU - Wessjohann, L. A. AU - Nin Brauer, M. C. AU - Brand, K. AU - VL - UR - SN - 978-90-481-3865-4 DO - 10.1007/978-90-481-3865-4_7 AB - Most current organocatalysts are based on nitrogen (or phosphorus) as reactive atom, including also most processes depending on proton acidity and/or Lewis basicity. Only few organocatalytic systems use organochalcogens, although such reactions are of great importance in nature, especially evident in hydrolases with serine or cysteine as catalytic hotspot, or in oxidoreductases with cysteine or selenocysteine as key players. Catalytic processes in nature commonly rely on the nucleophilic or redox properties of chalcogen atoms. Accordingly early attempts in chemical catalysis using organochalcogens concentrate either on systems reminiscent of catalytic diads and triads of enzymes with catalysts consisting of a hydroxyl or sulfhydryl group that is activated as nucleophile by a neighboring base (catalytic diads and triads). Other “traditional” uses of chalcogen-based catalysts comprise chiral dioxiranes and oxaziranes for epoxidations, and sulfur redox catalysts, the latter especially in the application of sulfur ylides covered by the predominant work of Aggarwal et al. Since the advent of “Organocatalysis” as a distinct subfield of catalysis, not only these traditional organochalcogen catalyst systems excelled; also new applications are more systematically studied now, including not only oxygen and sulfur but increasingly selenium – and to a smaller extent – even tellurium based catalysis [372]. If nature and its several thousand years of selection of catalysis modes serve as a reference, group VI-based catalysis is yet very much below its real potential in chemical organocatalysis. This contribution thus aims at giving the reader an entry into this so much underutilized field, which offers ample room especially for those who like to try new paths and who not only wish expand on existing processes of well ­established nitrogen-based catalysts. A2 - Mahrwald, R., ed. C1 - Bioorganic Chemistry ER -