Herbert Kogler

Isolation and Structural Elucidation of Armeniaspirols A–C: Potent Antibiotics against Gram‐Positive Pathogens

In an antibiotic lead discovery program, the known strain Streptomyces armeniacus DSM19369 has been found to produce three new natural products when cultivated on a malt-containing medium. The challenging structural elucidation of the isolated compounds was achieved by using three independent methods, that is, chemical degradation followed by NMR spectroscopy, a computer-assisted structure prediction algorithm, and X-ray crystallography. The compounds, named armeniaspirol A-C (2-4), exhibit a compact, hitherto unprecedented chlorinated spiro[4.4]non-8-ene scaffold. Labeling experiments with [1-(13)C] acetate, [1,2-(13)C2] acetate, and [U-(13)C] proline suggest a biosynthesis through a rare two-chain mechanism. Armeniaspirols displayed moderate to high in vitro activities against gram-positive pathogens such as methicillin-resistant S. aureus (MRSA) or vancomycin resistant E. faecium (VRE). As analogue 2 was active in vivo in an MRSA sepsis model, and showed no development of resistance in a serial passaging experiment, it represents a new antibiotic lead structure.

2-(2-pyridyl-)ethyl esters A new carboxyl protecting group in peptide synthesis

Abstract 2-(2-pyridyl-)ethyl esters are used as chemically inert, highly selective protecting groups that are removable under mild conditions via a two step procedure.

Butalactin: a new butanolide antibiotic from streptomyces corchorusii

Butalactin, (2R*,3S*)-2-(4′,5′-epoxy-hex-2′E-en)oyl-2-hydroxy-3-hydroxymethylbutanolide,(1) is a new antibiotic produced by a Streptomyces sp. HIL Y-86,36923. Butalactin is structurally related to the butyrolactones produced as signal molecules by microorganisms.

MACLAFUNGIN, A NEW ANTIFUNGAL MACROCYCLIC LACTONE FROM ACTINOMYCETE SP. Y-8521050

Abstract A new antifungal macrocyclic lactone maclafungin, belonging to the oligomycin class has been isolated from an actinomycete sp. Y-8521050. The antibiotic, having a molecular formula of C46H80O12, is active against several fungal species. Its structure was elucidated by analysis of 2D NMR experiments.