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  1. Article: A mechanistic study of oxygen atom transfer from N-sulfonyloxaziridine to enolates

    Foy, Hayden C / Adrian L. Schwan / Travis Dudding

    Tetrahedron. 2019 Apr. 05, v. 75, no. 14

    2019  

    Abstract: Enolate additions to chiral N-sulfonyloxaziridines providing enantiomerically enriched α-hydroxy carbonyl compounds is a reaction of importance, yet a clear understanding of the factors governing stereoinduction in these transformations remains ambiguous. ...

    Abstract Enolate additions to chiral N-sulfonyloxaziridines providing enantiomerically enriched α-hydroxy carbonyl compounds is a reaction of importance, yet a clear understanding of the factors governing stereoinduction in these transformations remains ambiguous. This is despite, previous computational studies, one by Bach et al. employing truncated model systems exploring oxygen atom transfer to an unsubstituted lithium enolate and another by our own group. In clarifying this reactivity we report here a computational study examining oxygen atom transfer from 1-S-(+)-(10-camphorsulfonyl)oxaziridine, viz., archetypal Davis chiral oxaziridine to substituted Li, Na, K enolates offering improved mechanistic understanding. From this investigation, a revised model is offered revealing the metal cation, chelation effects and sterics as decisive stereocontrolling factors in enolate additions to chiral N-sulfonyloxaziridines affording enantiomerically enriched α-hydroxy carbonyl compounds.
    Keywords carbonyl compounds ; chelation ; chemical structure ; lithium ; metal ions ; models ; oxygen ; potassium ; sodium
    Language English
    Dates of publication 2019-0405
    Size p. 2056-2061.
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 204285-x
    ISSN 1464-5416 ; 0040-4020 ; 0563-2064
    ISSN (online) 1464-5416
    ISSN 0040-4020 ; 0563-2064
    DOI 10.1016/j.tet.2019.02.051
    Database NAL-Catalogue (AGRICOLA)

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  2. Article ; Online: Characterization of Antifungal Natural Products Isolated from Endophytic Fungi of Finger Millet (Eleusine coracana)

    Walaa Kamel Mousa / Adrian L. Schwan / Manish N. Raizada

    Molecules, Vol 21, Iss 9, p

    2016  Volume 1171

    Abstract: Finger millet is an ancient African-Indian crop that is resistant to many pathogens including the fungus, Fusarium graminearum. We previously reported the first isolation of putative fungal endophytes from finger millet and showed that the crude extracts ...

    Abstract Finger millet is an ancient African-Indian crop that is resistant to many pathogens including the fungus, Fusarium graminearum. We previously reported the first isolation of putative fungal endophytes from finger millet and showed that the crude extracts of four strains had anti-Fusarium activity. However, active compounds were isolated from only one strain. The objectives of this study were to confirm the endophytic lifestyle of the three remaining anti-Fusarium isolates, to identify the major underlying antifungal compounds, and to initially characterize the mode(s) of action of each compound. Results of confocal microscopy and a plant disease assay were consistent with the three fungal strains behaving as endophytes. Using bio-assay guided fractionation and spectroscopic structural elucidation, three anti-Fusarium secondary metabolites were purified and characterized. These molecules were not previously reported to derive from fungi nor have antifungal activity. The purified antifungal compounds were: 5-hydroxy 2(3H)-benzofuranone, dehydrocostus lactone (guaianolide sesquiterpene lactone), and harpagoside (an iridoide glycoside). Light microscopy and vitality staining were used to visualize the in vitro interactions between each compound and Fusarium; the results suggested a mixed fungicidal/fungistatic mode of action. We conclude that finger millet possesses fungal endophytes that can synthesize anti-fungal compounds not previously reported as bio-fungicides against F. graminearum.
    Keywords finger millet ; Fusarium sp ; endophyte ; fungus ; Penicillium sp ; 5-hydroxy 2(3H)-benzofuranone ; dehydrocostus lactone ; harpagoside ; Organic chemistry ; QD241-441
    Language English
    Publishing date 2016-09-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: Synthetic lung surfactants containing SP-B and SP-C peptides plus novel phospholipase-resistant lipids or glycerophospholipids

    Robert H. Notter / Rohun Gupta / Adrian L. Schwan / Zhengdong Wang / Mohanad Gh Shkoor / Frans J. Walther

    PeerJ, Vol 4, p e

    2016  Volume 2635

    Abstract: Background This study examines the biophysical and preclinical pulmonary activity of synthetic lung surfactants containing novel phospholipase-resistant phosphonolipids or synthetic glycerophospholipids combined with Super Mini-B (S-MB) DATK and/or SP- ... ...

    Abstract Background This study examines the biophysical and preclinical pulmonary activity of synthetic lung surfactants containing novel phospholipase-resistant phosphonolipids or synthetic glycerophospholipids combined with Super Mini-B (S-MB) DATK and/or SP-Css ion-lock 1 peptides that replicate the functional biophysics of surfactant proteins (SP)-B and SP-C. Phospholipase-resistant phosphonolipids used in synthetic surfactants are DEPN-8 and PG-1, molecular analogs of dipalmitoyl phosphatidylcholine (DPPC) and palmitoyl-oleoyl phosphatidylglycerol (POPG), while glycerophospholipids used are active lipid components of native surfactant (DPPC:POPC:POPG 5:3:2 by weight). The objective of the work is to test whether these novel lipid/peptide synthetic surfactants have favorable preclinical activity (biophysical, pulmonary) for therapeutic use in reversing surfactant deficiency or dysfunction in lung disease or injury. Methods Surface activity of synthetic lipid/peptide surfactants was assessed in vitro at 37 °C by measuring adsorption in a stirred subphase apparatus and dynamic surface tension lowering in pulsating and captive bubble surfactometers. Shear viscosity was measured as a function of shear rate on a Wells-Brookfield micro-viscometer. In vivo pulmonary activity was determined by measuring lung function (arterial oxygenation, dynamic lung compliance) in ventilated rats and rabbits with surfactant deficiency/dysfunction induced by saline lavage to lower arterial PO2 to <100 mmHg, consistent with clinical acute respiratory distress syndrome (ARDS). Results Synthetic surfactants containing 5:3:2 DPPC:POPC:POPG or 9:1 DEPN-8:PG-1 combined with 3% (by wt) of S-MB DATK, 3% SP-Css ion-lock 1, or 1.5% each of both peptides all adsorbed rapidly to low equilibrium surface tensions and also reduced surface tension to ≤1 mN/m under dynamic compression at 37 °C. However, dual-peptide surfactants containing 1.5% S-MB DATK + 1.5% SP-Css ion-lock 1 combined with 9:1 DEPN-8:PG-1 or 5:3:2 DPPC:POPC:POPG had the greatest in ...
    Keywords Phospholipase-resistant lung surfactants ; Super Mini-B DATK ; SP-B and SP-C peptide mimics ; Surfactant protein B (SP-B) ; SP-Css ion-lock 1 ; DEPN-8 ; Medicine ; R ; Biology (General) ; QH301-705.5
    Subject code 610 ; 540
    Language English
    Publishing date 2016-10-01T00:00:00Z
    Publisher PeerJ Inc.
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article ; Online: Bis(2-bromobenzyl) trisulfide

    Adrian. L. Schwan / Alan. J. Lough / Suneel. P. Singh

    Acta Crystallographica Section E, Vol 65, Iss 2, Pp o361-o

    2009  Volume 361

    Abstract: The title molecule, C14H12Br2S3, lies on a crystallographic twofold rotation axis which bisects the S—S—S angle. The dihedral angle between the two symmetry-related benzene rings is 89.91 (9)°. In terms of hybridization principles, the S—C—C angle is ... ...

    Abstract The title molecule, C14H12Br2S3, lies on a crystallographic twofold rotation axis which bisects the S—S—S angle. The dihedral angle between the two symmetry-related benzene rings is 89.91 (9)°. In terms of hybridization principles, the S—C—C angle is slightly larger than expected.
    Keywords Chemistry ; QD1-999
    Language English
    Publishing date 2009-02-01T00:00:00Z
    Publisher International Union of Crystallography
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article ; Online: Triclinic modification of N-[(1,1-dimethylethoxy)carbonyl]-3-[(R)-prop-2-en-1-ylsulfinyl]-(R)-alanine ethyl ester at 120 (1) K

    Suneel P. Singh / Marcus J. Verdu / Alan J. Lough / Adrian L. Schwan

    Acta Crystallographica Section E, Vol 65, Iss 6, Pp o1387-o

    2009  Volume 1387

    Abstract: There are two independent molecules in the asymmetric unit of the title compound, C13H23NO5S. In the crystal structure, intermolecular N—H.O hydrogen bonds link molecules into two independent one-dimensional chains along [100]. The crystal studied was ... ...

    Abstract There are two independent molecules in the asymmetric unit of the title compound, C13H23NO5S. In the crystal structure, intermolecular N—H.O hydrogen bonds link molecules into two independent one-dimensional chains along [100]. The crystal studied was found to be a non-merohedral twin with a ratio of 0.615 (6):0.385 (1) for the refined components. At 200 (1) K [Singh et al. (2009). Acta Cryst. E65, o1385–o1386] the crystal structure of the title compound contains one disordered molecule in the asymmetric unit of a monoclinic unit cell.
    Keywords Chemistry ; QD1-999
    Language English
    Publishing date 2009-06-01T00:00:00Z
    Publisher International Union of Crystallography
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  6. Article ; Online: Monoclinic modification of N-[(1,1-dimethylethoxy)carbonyl]-3-[(R)-prop-2-en-1-ylsulfinyl]-(R)-alanine ethyl ester at 200 (1) K

    Suneel P. Singh / Marcus J. Verdu / Alan J. Lough / Adrian L. Schwan

    Acta Crystallographica Section E, Vol 65, Iss 6, Pp o1385-o

    2009  Volume 1386

    Abstract: In the monoclinic polymorph of the title compound, C13H23NO5S, intermolecular N—H.O hydrogen bonds link molecules into one-dimensional chains along [100]. The atoms of the terminal propenyl group are disordered over two sets of sites with refined ... ...

    Abstract In the monoclinic polymorph of the title compound, C13H23NO5S, intermolecular N—H.O hydrogen bonds link molecules into one-dimensional chains along [100]. The atoms of the terminal propenyl group are disordered over two sets of sites with refined occupancies of 0.69 (2) and 0.31 (2).
    Keywords Chemistry ; QD1-999
    Language English
    Publishing date 2009-06-01T00:00:00Z
    Publisher International Union of Crystallography
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  7. Article ; Online: Dynamic surface activity of a fully synthetic phospholipase-resistant lipid/peptide lung surfactant.

    Frans J Walther / Alan J Waring / Jose M Hernandez-Juviel / Larry M Gordon / Adrian L Schwan / Chun-Ling Jung / Yusuo Chang / Zhengdong Wang / Robert H Notter

    PLoS ONE, Vol 2, Iss 10, p e

    2007  Volume 1039

    Abstract: This study examines the surface activity and resistance to phospholipase degradation of a fully-synthetic lung surfactant containing a novel diether phosphonolipid (DEPN-8) plus a 34 amino acid peptide (Mini-B) related to native surfactant protein (SP)-B. ...

    Abstract This study examines the surface activity and resistance to phospholipase degradation of a fully-synthetic lung surfactant containing a novel diether phosphonolipid (DEPN-8) plus a 34 amino acid peptide (Mini-B) related to native surfactant protein (SP)-B. Activity studies used adsorption, pulsating bubble, and captive bubble methods to assess a range of surface behaviors, supplemented by molecular studies using Fourier transform infrared (FTIR) spectroscopy, circular dichroism (CD), and plasmon resonance. Calf lung surfactant extract (CLSE) was used as a positive control.DEPN-8+1.5% (by wt.) Mini-B was fully resistant to degradation by phospholipase A(2) (PLA(2)) in vitro, while CLSE was severely degraded by this enzyme. Mini-B interacted with DEPN-8 at the molecular level based on FTIR spectroscopy, and had significant plasmon resonance binding affinity for DEPN-8. DEPN-8+1.5% Mini-B had greatly increased adsorption compared to DEPN-8 alone, but did not fully equal the very high adsorption of CLSE. In pulsating bubble studies at a low phospholipid concentration of 0.5 mg/ml, DEPN-8+1.5% Mini-B and CLSE both reached minimum surface tensions <1 mN/m after 10 min of cycling. DEPN-8 (2.5 mg/ml)+1.5% Mini-B and CLSE (2.5 mg/ml) also reached minimum surface tensions <1 mN/m at 10 min of pulsation in the presence of serum albumin (3 mg/ml) on the pulsating bubble. In captive bubble studies, DEPN-8+1.5% Mini-B and CLSE both generated minimum surface tensions <1 mN/m on 10 successive cycles of compression/expansion at quasi-static and dynamic rates.These results show that DEPN-8 and 1.5% Mini-B form an interactive binary molecular mixture with very high surface activity and the ability to resist degradation by phospholipases in inflammatory lung injury. These characteristics are promising for the development of related fully-synthetic lipid/peptide exogenous surfactants for treating diseases of surfactant deficiency or dysfunction.
    Keywords Medicine ; R ; Science ; Q
    Subject code 500
    Language English
    Publishing date 2007-10-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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