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 Cofactor‐Induced Combinatorial Pairing of Stig Cyclases

Stereospecific polycyclic core formation of hapalindoles and fischerindoles is controlled by Stig cyclases through a three‐step cascade involving Cope rearrangement, 6‐exo‐trig 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 Stig‐Cyclasen gesteuert, die eine dreistufige Kaskade aus Cope‐Umlagerung, 6‐exo‐trig‐Cyclisierung 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

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 Marfey’s 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 IC₅₀ values of 0.26 and 2.93 μM, respectively