4''-O-(omega-Quinolylamino-alkylamino)propionyl derivatives of selected macrolides with the activity against the key erythromycin resistant respiratory pathogens.

Four macrolides-6-O-methyl-8a-aza-8a-homoerythromycin, clarithromycin, azithromycin and azithromycin 11,12-cyclic carbonate, have been selected for the construction of a series of new quinolone derivatives. The quinolone moiety is connected to the macrolide scaffold via a diaminoaklyl 4''-O-propionyl ester chain of varying length. At the terminus the linker is attached via one of the nitrogen atoms in the linker at C(6) or C(7) of the quinolone. Many of compounds described, particularly clarithromycin derivative 37, and azithromycin derivatives 48 and 55, exhibited excellent antibacterial activity against a wide range of clinically relevant macrolide-resistant organisms, with profiles superior to that of telithromycin, an enhanced spectrum ketolide.

New oleandomycin 9-oximes. Synthesis, characterization and biological activity.

A series of the novel oleandomycin 9-oximes has been prepared and characterized by spectroscopic data and X-ray analysis. The antibacterial in vitro activities of the oximes (6-10) were compared with that of oleandomycin (1). Among the novel derivatives the most active compound was 8(R)-methyloleandomycin-9-oxime (9) in contrast ot its 8(S)-isomer (10) which possessed only low potency. Some preliminary pharmacokinetic data of 9 confirmed its activity. Compound 9 has been advanced to further biological study.

9a,11-cyclic carbamates of 15-membered azalides.

The novel 9a,11-cyclic carbamates (13-15) of 9-deoxo-9a-aza-9a-homoerythromycin A (4) have been prepared and characterized by 1H-1H and 1H-13C 2D NMR spectroscopy. When compared to azithromycin (1) or its 6-O-methyl derivative (2), the new bicyclic 15-membered azalides exhibited substantially decreased antibacterial activities in vitro.

Synthesis and antibacterial activity of O-methylazithromycin derivatives.

A series of O-methylazithromycin derivatives have been synthesized and their antibacterial activities were compared with those of azithromycin (1). O-Methylation of 1 proceeded stepwise by the two main pathways beginning at the C-6 and C-11 hydroxyl groups, individually. Among O-methyl derivatives, 6-O-methylazithromycin A (11) was slightly less active than 1. The methylation of the secondary hydroxyl group at the C-11 position resulted surprisingly in an increase of their in vitro activity. The antibacterial activities of novel azalides decreased with increasing the number of the methyl groups introduced.

Erythromycin series. XII. Antibacterial in vitro evaluation of 10-dihydro-10-deoxo-11-azaerythromycin A: synthesis and structure-activity relationship of its acyl derivatives.

Antibacterial in vitro evaluation of 10-dihydro-10-deoxo-11-azaerythromycin A (5), the new 15-membered semi-synthetic macrolide antibiotic with nitrogen as additional atom in the aglycone ring of erythromycin A (1), was reported. Although amine (5) and its 13,14-cyclic carbonate (14) were less active than 1 against erythromycin-sensitive Staphylococcus aureus strains they showed advantageous properties against Gram-negative test organisms and clinical isolates. Also, a large number of acyl derivatives of 5 were synthesized and evaluated. N-11 monoacyl compounds exhibited 2 to 50 times lower in vitro antibacterial efficacy than the parent amine (5).