Determination of degradation products of squalamine lactate using LC/MS.

Heat, acid and base stress methods were applied to study the stability of squalamine lactate. Liquid chromatography coupled with mass spectrometry was used to analyze the degraded samples and tentative structural identifications were assigned based on their molecular weight measurements, reactivity and MS/MS fragmentation. Solid squalamine lactate generated a new amide, namely lactyl squalamide, when heated to 80 degrees C.

Antimicrobial activity of magainin analogues against anaerobic oral pathogens.

Magainins are a family of potent antimicrobial cationic peptides that possess antimicrobial activity against a wide range of target organisms. In this study, the antimicrobial activity of synthetic magainin-mimetic compounds MSI-751 and MSI-774 was investigated against the periodontal pathogens Porphyromonas gingivalis, Fusobacterium nucleatum, Actinobacillus actinomycetemcomitans, Eikenella corrodens, Prevotella loescheii and Prevotella intermedia. P.

A novel linear amphipathic beta-sheet cationic antimicrobial peptide with enhanced selectivity for bacterial lipids.

All known naturally occurring linear cationic peptides adopt an amphipathic alpha-helical conformation upon binding to lipids as an initial step in the induction of cell leakage. We designed an 18-residue peptide, (KIGAKI)3-NH2, that has no amphipathic character as an alpha-helix but can form a highly amphipathic beta-sheet. When bound to lipids, (KIGAKI)3-NH2 did indeed form a beta-sheet structure as evidenced by Fourier transform infrared and circular dichroism spectroscopy.

Human beta-defensin-1 is a salt-sensitive antibiotic in lung that is inactivated in cystic fibrosis.

A human bronchial xenograft model was used to characterize the molecular basis for the previously described defect in bacterial killing that is present in the cystic fibrosis (CF) lung. Airway surface fluid from CF grafts contained abnormally high NaCl and failed to kill bacteria, defects that were corrected with adenoviral vectors. A full-length clone for the only known human beta-defensin (i.

Structure-activity studies on magainins and other host defense peptides.

Host defense peptides are widely distributed in nature, being found in species from bacteria to humans. The structures of these peptides from insects, horseshoe crabs, frogs, and mammals are known to have the common features of a net cationic charge due to the presence of multiple Arg and Lys residues and in most cases the ability to form amphipathic structures. These properties are important for the mechanism of action that is thought to be a nonreceptor-mediated interaction with the anionic phospholipids of the target cell followed by incorporation into the membrane and disruption of the membrane structure.