Ligand-induced perturbations in Urtica dioica agglutinin

AbstractThe binding of the trisaccharide, N,N′,N″-triacetylchitotriose, to Urtica dioica agglutinin (UDA) was investigated using 1H NMR spectroscopy. UDA is a small antiviral plant lectin containing two homologous 43-amino acid domains. Carbohydrate-induced perturbations occur in one domain of UDA at trisaccharide concentrations below equimolar. Residues in the second domain are shifted at higher carbohydrate concentrations. This data confirms the presence of two binding sites of non-identical affinities per UDA monomer. Qualitative analysis of the 2D NOESY spectra indicates that UDA contains two short stretches of antiparallel β-sheet. The 1H resonance assignments for both antiparallel β-sheet sequences have been completed and there is one β-stretch per domain. A number of these β-sheet residues are perturbed in the presence of carbohydrate

Synthesis and Structural Elucidation of a Pyranomorphinan Opioid and in Vitro Studies

During optimization of the synthesis of the mixed μ opioid agonist/δ opioid antagonist 5-(hydroxy­methyl)­oxy­morphone (UMB425) for scale-up, it was unexpectedly discovered that the 4,5-epoxy bridge underwent rearrangement on treatment with boron tribromide (BBr₃) to yield a novel opioid with a little-studied pyranomorphinan skeleton. This finding opens the pyranomorphinans for further investigations of their pharmacological profiles and represents a novel drug class with the dual profile (μ vs δ) predicted to yield lower tolerance and dependence. The structure was assigned with the help of 1D, 2D NMR and the X-ray crystal structure

Small Molecule Antivirulents Targeting the Iron-Regulated Heme Oxygenase (HemO) of <i>P. aeruginosa</i>

Bacteria require iron for survival and virulence and employ several mechanisms including utilization of the host heme containing proteins. The final step in releasing iron is the oxidative cleavage of heme by HemO. A recent computer aided drug design (CADD) study identified several inhibitors of the bacterial HemOs. Herein we report the near complete HN, N, CO, Cα, and Cβ chemical shift assignment of the <i>P. aeruginosa</i> HemO in the absence and presence of inhibitors (<i>E</i>)-3-(4-(phenylamino)­phenylcarbamoyl)­acrylic acid (<b>3</b>) and (<i>E</i>)-<i>N</i>′-(4-(dimethylamino)­benzylidene) diazenecarboximidhydrazide (<b>5</b>). The NMR data confirm that the inhibitors bind within the heme pocket of HemO consistent with in silico molecular dynamic simulations. Both inhibitors and the phenoxy derivative of <b>3</b> have activity against <i>P. aeruginosa</i> clinical isolates. Furthermore, <b>5</b> showed antimicrobial activity in the in vivo C. elegans curing assay. Thus, targeting virulence mechanisms required within the host is a viable antimicrobial strategy for the development of novel antivirulants

Cranberry Xyloglucan Structure and Inhibition of Escherichia coli Adhesion to Epithelial Cells

Cranberry juice has been recognized as a treatment for urinary tract infections on the basis of scientific reports of proanthocyanidin anti-adhesion activity against Escherichia coli as well as from folklore. Xyloglucan oligosaccharides were detected in cranberry juice and the residue remaining following commercial juice extraction that included pectinase maceration of the pulp. A novel xyloglucan was detected through tandem mass spectrometry analysis of an ion at <i>m</i>/<i>z</i> 1055 that was determined to be a branched, three hexose, four pentose oligosaccharide consistent with an arabino-xyloglucan structure. Two-dimensional nuclear magnetic resonance spectroscopy analysis provided through-bond correlations for the α-l-Ara<i>f</i> (1→2) α-d-Xyl<i>p</i> (1→6) β-d-Glc<i>p</i> sequence, proving the S-type cranberry xyloglucan structure. Cranberry xyloglucan-rich fractions inhibited the adhesion of <i>E. coli</i> CFT073 and UTI89 strains to T24 human bladder epithelial cells and that of <i>E. coli</i> O157:H7 to HT29 human colonic epithelial cells. SSGG xyloglucan oligosaccharides represent a new cranberry bioactive component with <i>E. coli</i> anti-adhesion activity and high affinity for type 1 fimbriae