DNA-directed aniline mustards based on 9-aminoacridine: interaction with DNA.

A series of 4-substituted aniline mustards ArNH(CH2)nOpC6H4N(CH2CH2Cl)2, where Ar is an acridine and n varies from 2 to 5, interact with DNA. Scatchard analysis shows the compounds bind tightly, with a binding site size similar to that of 9-aminoacridine. The rate of hydrolysis of the mustards, measured by HPLC, is essentially constant across the series. With increasing length of the polymethylene linker, non-covalent binding becomes less strong, but the rate of DNA alkylation increases. Viscometric helix extension measurements and electrophoretic analyses using closed circular supercoiled DNA show that all the compounds are DNA intercalating ligands. Despite these similarities, the compounds are known to have quite different patterns of DNA alkylation, switching from guanine to adenine alkylation as the chain length is extended.     

Pulsed-field gel electrophoresis typing of Hafnia alvei isolated from chub-packed and retail ground beef

Thirty-eight isolates of Hafnia alvei were characterized by biochemical profiles, ribotyping and pulsed-field gel electrophoresis (PFGE) patterns. The isolates were recovered from chub-packed (19 isolates) or retail (nine isolates) ground beef, or were obtained from culture repositories (10 isolates). Biochemical profiling differentiated the 38 isolates into five groups and a commercial ribotyping method recognized 11 groups, whereas PFGE differentiated the same 38 isolates into 19 groups. These data substantiate that PFGE is a highly discriminatory tool for establishing the relatedness among Hafnia alvei strains.     

Anti-bacterial activity of extracts from the brown seaweed Stoechospermum marginatum

The methanol extract of the brown seaweed Stoechospermum marginatum was found to inhibit the growth of Staphylococcus aureus. The active constituents were found to be a mixture of diterpenoid monoacetates having the spatane skeleton.