Synthesis, activity and pharmacokinetics of novel antibacterial 15-membered ring macrolones.

Synthesis, antibacterial activity and pharmacokinetic properties of a novel class of macrolide antibiotics-macrolones-derived from azithromycin, comprising oxygen atom(s) in the linker and either free or esterified quinolone 3-carboxylic group, are reported. Selected compounds showed excellent antibacterial potency towards key erythromycin resistant respiratory pathogens. However, the majority of compounds lacked good bioavailability. The isopropyl ester, compound 35, and a macrolone derivative with an elongated linker 29 showed the best oral bioavailability in rats, both accompanied with an excellent overall microbiology profile addressing inducible and constitutive MLSb as well as efflux mediated macrolide resistance in streptococci, while compound 29 is more potent against staphylococci.

Free and bound state structures of 6-O-methyl homoerythromycins and epitope mapping of their interactions with ribosomes.

The solution and solid state conformations of several 6-O-methyl homoerythromycins 1-4 were studied using a combination of X-ray crystallography, NMR spectroscopy and molecular modelling calculations. In the solid state 1 was found to exist as the two independent molecules with similar structures termed 3-endo-folded-out. In solution a significant conformational flexibility was noticed especially in the C2 to C5 region. The compounds 1 and 2 unlike 14-membered macrolides adopted the 3-endo-folded-out conformation while 3 and 4 existed in the classical folded-out conformation. TrNOESY and STD experiments showed that 1 and 2 bound to the Escherichia coli ribosome while 3 and 4, lacking the cladinose sugar, did not exhibit binding activities, this being in accordance with biochemical data. The bound conformations were found to be very similar to the free ones, some small differences were observed and discussed. The STD experiments provided evidence on binding epitopes. The structural parts of 1 and 2 in close contact with ribosome were similar, however the degree of saturation transfer was higher for 2. The differences between tr-NOE data and STD enhancements in 1 and 2 arouse as a consequence of structural changes upon binding and a closer proximity of 2 to the ribosome surface. An understanding of the molecular mechanisms involved in the interaction of macrolides with ribosomes can help in developing strategies aiming at design of potential inhibitors.

Supramolecular structures of three isomeric 4-(methylphenylamino)pyridine-3-sulfonamides.

The structures of the three title isomers, namely 4-(2-methylanilino)pyridine-3-sulfonamide, (I), 4-(3-methylanilino)pyridine-3-sulfonamide, (II), and 4-(4-methylanilino)pyridine-3-sulfonamide, (III), all C(12)H(13)N(3)O(2)S, differ in their hydrogen-bonding arrangements. In all three molecules, the conformation of the 4-aminopyridine-3-sulfonamide moiety is conserved by an intramolecular N-H...O hydrogen bond and a C-H...O interaction. In the supramolecular structures of all three isomers, similar C(6) chains are formed via intermolecular N-H...N hydrogen bonds. N-H...O hydrogen bonds lead to C(4) chains in (I), and to R(2)(2)(8) centrosymmetric dimers in (II) and (III). In each isomer, the overall effect of all hydrogen bonds is to form layer structures.

Tolterodinium (+)-(2R,3R)-hydrogen tartrate.

In the crystal structure of (R)-N,N-diisopropyl-3-(2-hydroxy-5-methylphenyl)-3-phenylpropylaminium (2R,3R)-hydrogen tartrate, C22H32NO+.C4H5O6-, the hydrogen tartrate anions are linked by O-H...O hydrogen bonds to form helical chains built from R(2)(2)(9) rings. These chains are linked by the tolterodine molecules via N-H...O and O-H...O hydrogen bonds to form separate sheets parallel to the (101) plane.