46 research outputs found
Antimicrobial Activity of Croton macrostachyus Stem Bark Extracts against Several Human Pathogenic Bacteria
Peer reviewe
Control of Stereoselectivity in Diverse Hapalindole Metabolites is Mediated by CofactorâInduced Combinatorial Pairing of Stig Cyclases
Stereospecific polycyclic core formation of hapalindoles and fischerindoles is controlled by Stig cyclases through a threeâstep cascade involving Cope rearrangement, 6âexoâtrig cyclization, and a final electrophilic aromatic substitution. Reported here is a comprehensive study of all currently annotated Stig cyclases, revealing that these proteins can assemble into heteromeric complexes, induced by Ca2+, to cooperatively control the stereochemistry of hapalindole natural products.Die stereospezifische Bildung des polycyclischen Kerns der Hapalindole und Fischerindole wird durch StigâCyclasen gesteuert, die eine dreistufige Kaskade aus CopeâUmlagerung, 6âexoâtrigâCyclisierung und elektrophiler aromatischer Substitution vermitteln. Die Proteine können sich induziert durch Ca2+ zu heterotrimeren Komplexen zusammenlagern, um auf kooperative Weise die Stereochemie zu steuern.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/155506/1/ange201913686.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/155506/2/ange201913686-sup-0001-misc_information.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/155506/3/ange201913686_am.pd
A Novel Extracellular Diterpenoid with Antibacterial Activity from the Cyanobacterium Nostoc commune
Sanctolide A, a 14-membered PK-NRP hybrid macrolide from the cultured cyanobacterium Oscillatoria sancta (SAG 74.79)
Sanctolide A (1), a 14-membered polyketide-nonribosomal peptide (PK-NRP) hybrid macrolide, was isolated from the cultured cyanobacterium Oscillatoria sancta (SAG 74.79). The planar structure was determined using various spectroscopic techniques including HRESIMS, and 1D and 2D NMR analyses. The relative configuration was assigned by J-based configurational analysis in combination with NOE correlations. The absolute configuration was determined by Mosher ester and enantioselective HPLC analyses. The structure of sanctolide A (1) features a rare N-methyl enamide and a 2-hydroxyisovaleric acid, which are incorporated to form a 14-membered macrolide ring structure, comprising a new type of cyanobacterial macrolides derived from a PKS-NRPS hybrid biosynthetic pathway
Stigonemapeptin, an Ahp-Containing Depsipeptide with Elastase Inhibitory Activity from the Bloom-Forming Freshwater Cyanobacterium <i>Stigonema</i> sp.
Stigonemapeptin (<b>1</b>), a depsipeptide containing
an
Ahp (3-amino-6-hydroxy-2-piperidone) residue, was isolated from a
bloom sample of the freshwater cyanobacterium <i>Stigonema</i> sp. collected from North Nokomis Lake in the Highland Lake District
of northern Wisconsin. The planar structure was determined by 1D and
2D NMR experiments as well as HRESIMS analysis. The absolute configurations
of the amino acids were determined using the advanced Marfeyâs
method after acid hydrolysis. Stigonemapeptin (<b>1</b>), characterized
by the presence of the Ahp residue, also contained the modified amino
acids Abu (2-amino-2-butenoic acid) and <i>N</i>-formylated
Pro. Stigonemapeptin (<b>1</b>) showed <i>in vitro</i> elastase and chymotrypsin inhibitory activity, with IC<sub>50</sub> values of 0.26 and 2.93 ÎŒM, respectively