WYE-120318, a ring contraction product of methylnaltrexone, and structure revision of coniothyrione.

A contracted ring degradation product, WYE-120318 (compound 2), was discovered during the development phase for methylnaltrexone bromide (compound 1) drug substance. The compound was isolated by high-performance liquid chromatography fractionation, and its structure was determined by spectroscopic data analyses. WYE-120318 is formed from methylnaltrexone through a benzyl-benzilic acid type rearrangement reaction to yield an α-hydroxy-cyclopentanecarboxylic acid substructure.

Structural characterization of the tobramycin-piperacillin reaction product formed at pH 6.0.

Tobramycin is an aminoglycoside antibiotic that loses a significant amount of activity in the presence of Zosyn at pH 6. As part of our investigation into ways to improve the compatibility of tobramycin with Zosyn (which contains piperacillin and tazobactam in an 8:1 ratio buffered at pH 6 by sodium citrate) by lowering the pH, we identified the reaction product of tobramycin and piperacillin at pH 6.0 and the order of the pK(a) values of tobramycin.

Isolation and structure of homotemsirolimuses A, B, and C.

Homotemsirolimuses A, B, and C (2a, 2b, 2c) were found to be minor components of a temsirolimus preparation made from rapamycin. These three temsirolimus analogues are derived from the corresponding rapamycin analogues, homorapamycins A, B, and C (1a, 1b, 1c) produced by the strain Streptomyces hygroscopicus. The structures of homotemsirolimuses A, B, and C were determined by spectroscopic methods.

Design and synthesis of HCV agents with sequential triple inhibitory potentials.

The union of HCV-796, a potent selective HCV NS5B polymerase inhibitor, and Ribavirin, a molecule with activities against a wide spectrum of viruses, resulted in a class of new anti-HCV agents with a sequential triple inhibitory mechanism.

Synthesis and SAR of novel 4-morpholinopyrrolopyrimidine derivatives as potent phosphatidylinositol 3-kinase inhibitors.

Significant evidence suggests that deregulation of the PI3K/Akt pathway is important in tumor progression. Mechanisms include loss of function of the tumor suppressor PTEN and high frequency of mutation of the PI3K p110alpha isoform in human malignancies. This connection between PI3K and tumor genesis makes PI3K a promising target for cancer treatment.

Structure characterization of lipocyclopeptide antibiotics, aspartocins A, B & C, by ESI-MSMS and ESI-nozzle-skimmer-MSMS.

Three lipocyclopeptide antibiotics, aspartocins A (1), B (2), and C (3), were obtained from the aspartocin complex by HPLC separation methodology. Their structures were elucidated using previously published chemical degradation results coupled with spectroscopic studies including ESI-MS, ESI-Nozzle Skimmer-MSMS and NMR. All three aspartocin compounds share the same cyclic decapeptide core of cyclo [Dab2 (Asp1-FA)-Pip3-MeAsp4-Asp5-Gly6-Asp7-Gly8-Dab9-Val10-Pro11].

Septocylindrins A and B: peptaibols produced by the terrestrial fungus Septocylindrium sp. LL-Z1518.

Two new peptaibols, septocylindrin A (1) and septocylindrin B (2), related to the well-studied membrane-channel-forming peptaibol alamethicin, were obtained from a terrestrial isolate of the fungus Septocylindrium sp. Both 1 and 2 are linear 19-amino acid peptides with a modified phenylalanine C-terminus. Analysis of the HRMS data indicated that they differ only in the 18th residue, where 1 contains Glu and 2 contains Gln.

Hygrocins a and B, naphthoquinone macrolides from Streptomyces hygroscopicus.

Two new naphthoquinone macrolides, hygrocins A (1) and B (2), were isolated from the fermentation broth of Streptomyces hygroscopicus. Hygrocin A is not stable due to the presence of an active methylene group (C-22), which undergoes intramolecular aldol condensation with the quinone ring to yield a gamma-lactam derivative, 6. Its structural elucidation was achieved by chemical conversion to 3, an unusual diazomethane derivative, and confirmed by its alkaline hydrolysis product 4, hydrogenation derivative 5, and "degradation" product 6.

Pseudopyronines A and B, alpha-pyrones produced by a marine Pseudomonas sp. F92S91, and evidence for the conversion of 4-hydroxy-alpha-pyrone to 3-furanone.

In our search for inhibitors of bacterial fatty acid biosynthesis, two new alpha-pyrones, pseudopyronines A (1) and B (2), were isolated from a marine Pseudomonas sp. F92S91. The naturally occurring alpha-pyrones appeared to be unstable, evidenced by the conversion of pseudopyronine B into an oxidation product, 3-furanone (3).

Novel alpha-pyrones produced by a marine Pseudomonas sp. F92S91: taxonomy and biological activities.

Inhibitors of the enzymes involved in fatty acid biosynthesis (FAB) have been reported as antibacterial agents. These include thiolactomycin, cerulenin, triclosan, diazoborine, naphthyridinones, aminopyridines and pyridoindoles. Our search for new FAB inhibitors, using a lacZ reporter cell-based screen, led to several confirmed hits.

Structure determination of glycinocins A to D, further evidence for the cyclic structure of the amphomycin antibiotics.

Four novel cyclolipopeptides, glycinocins A to D, were isolated from the fermentation broth of an unidentified terrestrial Actinomycete species. These compounds were separated and purified from the fermentation broth by 1-butanol extraction, followed by repeated reversed-phase HPLC. Their structures were elucidated by spectroscopic and chemical degradation studies.